Chemistry 101 lecture Notes fall 2014 Finnegan
Chemistry 101 lecture Notes fall 2014 Finnegan Chem 101
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Chem 101 notes 82514 Needs 0 Text book 0 Modified masteringchemistry 0 Access code 0 Laboratory notebook Fulmer 18bookstore 0 Bring laptop Weekly HW sets are on masteringchemistry site this site is accessed trough blackboard httpelearningwsuedublackboard you will need an access code register according to the instructor attached Fulmer 319A The General Chem Office this is were you schedule make up labs Fulmer 3193rd floor right next door to 319A TA office hours are held in this room Fulmer 318 more Ta Offices here googles and lab notebooks will be sold here Fulmer 401 the chem department computer lab Questions 0 Is the book the same as last year 0 Yes 0 Missing first lab 0 Go to diff section 0 Conflict with ACCTG 230 midterm and final 0 Check dates Chem notes 82714 0 Registering for Mastering Chemistry 0 Pearson is experiencing problems with their registration server If you encounter a quotgateway errorquot just keep trying It is intermittent ant they are working to fix the problem 0 If you are asked for a quotcourse IDquot you are in the wrong place Follow the intrusions attached to the syllabus not the instructions on the insert card 0 The URL for Blackboard is Httpelearningwsuedublackboard All Forward Slashes o The Universe 0 Energy 0 Matter 0 Mixtures 0 Pure substances I Elements I Compounds 0 Molecular compounds 0 Ionic compounds The Unit erase Matter Energy Physical P t methods W l i MiIllfilill ES Emma mm Elliemit Enmpnun s Harmemits r iiipints junHill by emailEl Iliumnude minus and millions HlH lltEIIF 111111 crimpminth trimminde Terms 0 000000 Physical changes the substance changes its from but not identity For example changes in physical sate solid liquid gas dissolving in a solvent Solid the atoms ions or molecules are locked in place with respect to each other Liquid the atoms irons or molecules move around each other but remain near each other Gas the atoms iron or molecules are separated from each other and move independently Chemical change a reaction substance are converted into other substance Reactants the initial substance are converted into products the substance created by the reaction Element a substance made up of only one type of atom H Hydrogen V Vanadium He Helium Cr Chromium Li Lithium Mn manganese Be Beryllium Fe iron B Boron Cocobalt C Carbon Ni nickel N Nitrogen Cu copper 0 Oxygen Zu Zinc F Fluorine Ne Neon Na Sodium Rb Rubidium Mg Magnesium Cs Cesium Al Aluminum Sr Strontium Si Silicon Ba Barium P Phosphorus S Sulfur or sulphur Cl Chorine Au gold Ar Argon Ag Silver K Potassium Hg Mercury Ca Calcium Sn Tin Sc Scandium Pb lead Ti Titanium Br Bromine Compounds a pure substance made up of more then one type of atom help together by chemical bonds 0 Chemical formula 0 0 Each element present in a compound is represented by its symbol written in order they are found in the periodic table 0 The number or atom of each element is represented by a subscript after the symbol of the element lower right hand corner For the following compounds what elements are present and how many atoms or each elements are in one unit of the compound 0 C8H603C2 I Carbon 8 atoms I Hydrogen 6 atoms I Oxygen 3 atoms I Chlorine 2 atoms o C6H5NH2 I Carbon 6 atoms I Hydrogen 7 atoms I Nitrogen 1 atoms 0 CoCO42 I Cobalt 1 atoms I Chlorine 2 atoms I Oxygen 8 atoms 0 A2so43 I Aluminum 2 atoms I Sulfur 3 atoms I Oxygen 12 atoms Chem notes 82914 Metals left side of periodic table Nonmetals Right side of the table Metalloids aka semimetals quotstairstep between the metals and nonmetals Chemistry is based on the behavior of charged particles Positive charges and negative charges attract each other Like charges positivepositive or negativenegative repel each other Atoms are composed of subatomic particles Table 21 protons neutrons and electrons In an atom the protons and the neutrons are packed together in a dense center called the nucleus Electrons occupy the space surrounding the nucleus How do atoms differ from one another In the number of protons neutrons and electrons present Atomic number represented by Z This is the number of protons present in the nucleus of the atom The number of protons is what distinguishes one element from another As an atom in its elemental state is always electronically neutral the atomic number is also the number of electrons present For neutral atoms of protons of electrons Mass number Represented by A This is the number of protons and neutrons present in the atom So A Z of neutrons Chem 101 notes 9314 Electrons in an atom are restricted to a specific set of energy values The energy levels are quantized Although the actual energy values change from element to element the energy levels of all elements are organized in a specific pattern energy levelan orbital a specific region of space near the nucleus An orbital energy level can hold two electrons Orbitals are organized into shells levels based on average distance between the orbital and the nucleus Shells are given a number n The first shell n1 is the closest to the nucleus and the lowest in energy The second shell n2 is a little farther out and higher in energy An so on for n 3 4 5 Orbitals within a shell are organized into subshells sublevels based on the shape of the orbital Each shape is identified by a letter s p d or f sorbitals are the lowest in energy forbitals are the highest Energy order sltpltdltf Each shell will have as many subshells as its number There may only be one s orbital per level 0 p orbitals are found in sets of 3 o d orbitals are found in sets of 5 o forbitals are found in sets of 7 An orbital can therefore be designated by citing the shell number and the letter for the subshell for example a ls orbital a 3p orbital etc So an atom will have a single 4d subshell consisting of five 4d orbitals Each orbital can hold two electrons so the 4d subshell can hold a maximum of 10 electrons The energy levels in a hydrogenlike atom ls Zs 2p 35 3p 45 3d 4p 55 4d 5p 65 4f 5d 6p 7s 5f 6d Etc What is the maximum number of electrons that may be placed in The 4p subshell 4p sublevel o 6 e 2 orbitals in 3 sublevels 236 The 2nd shell main energy level 2 o 8e 4 orbitals 2 elections in each 428 The 3rd shell main energy level 3 o 186 9 orbitals 2 elections in each 9218 A 5d orbital o 2e All orbitals only have 2 elections Ground state the lowest energy configuration of an atom or molecule all electrons in the lowest energy orbitals available Using the energy level diagram can write ground state electron configurations for atoms of any element Chem 101 notes 9514 0 Ground state the lowest energy configuration of an atom or molecule all electrons in the lowest energy orbital available 0 Using the energy level diagram can write ground state electrons configuration for atoms of any elections 0 H o 131 0 He 0 132 0 Li 0 132 231 0 Be 0 132 232 O B 0 132232 2p1 0 C 0 132232 2p2 0 N 0 132232 2p3 0 O 0 1322322194 0 Mg 0 132 232 2196332 0 V 0 132 232 2196332 3p64s33d3 o Orbital box diagram 0 N ll39 ll ls Zs 2p ll if llllll ls Zs 2p ll llllll 4W llljkljf 35 3p 45 3d 0 Write the ground state electrons configuration for tin 0 Sn 132 232 2196332 31964333d104196524d105p2 0 Short cut so you don t have to write everything out 0 Sn Kr5324d105p2 0 You can go back to the last noble gas Kr but not In it has to be the last noble gas 0 Write the election configuration of iodine using the noble gas shorthand notation oK 5324d105p5 O Bromine Br Ar4323d104p5 O Chlorine CI Ne3323p5 O Fluorine FHe2322p5 o Valance elections The elections occupying the outermost energy level of atom o The outermost level is the valance shell 0 How many valance elections do the halogens have 0 7 valance elections 0 The valence level election configuration for O The halogens nsznp5 O The alkali metals 0 n51 0 L He 251 0 Group 5A the nitrogen group 0 nsznp3 N He2522p3 O The nickel groups 0 nszn 1d4 N Ar4323d3 o 10 valance e o How many valance electrons dose one atom of each of the following element have 0 Be 0 2 O Si 0 4 O K o 1 0 Cr 0 6 0 Zn 0 2 0 Sn 0 4 0 Pt 0 10 0 Elements in a group on the periodic table have the same electron configuration in the valance shell 0 The electron configuration of an atom in the primary determinant of its chemical behavior Chem 101 notes 101 14 Main group atoms from irons or compounds in order atom achieve the noble gas electron configuration nsznp6 Write the electron configuration and dot symbol for Mg 0 Mg Ne 332 o IMgI What irons will Mg make 0 Mg2 What is the electron configuration and dot symbol for this iron 0 Mg Ne o Mg2 no dots beacuse there are no valance electrons left Answer the above questions for P o PNe3sz3p3 P o Irons P3 0 P339Ne3323p6 o P The IUPAC system the quotnew namequot in the textsee section 37312 411 pages 916 in your lab manual Cations add the word quotion to the element name the change on the main group cation is easily predicted 0 Sodium Na I Sodium iron Na o Strontium Sr I Strontium 51quot2 0 Aluminum Al I AluminumAl3 For transition metal and posttransition metal irons the change is given as a roman numeral in parentheses after the element name 0 Fe2 iron ion 0 Fe3 iron ion 0 Manganese ion Mn2 o TinV ion 511 Exceptions o The zinc ion Zn2 o The silver ion Ag Anion are named by taking the name od the element changing the ending to ide and adding the word quotionquot 0 Chlorine Clz I Chloride Cl 0 Sulfur S Sulfide 52 o Nitrogen N2 I Nitride ion N3 Polyatomic ion 0 Group of atoms held together by convent bonds but possessing an overall change molecules that are ions 0 Page 12 of the lab manual lists the polyatomic ions you are expected to know 0 Pay extra attention to these seven ions I NH4 Ammonium ion I SO24 Sulfate ion I NO3 Nitrate ion I 0H39 Hydroxide ion I POEPhosphate ion I C0 39Carbonate ion I C2H3 0239 Acetate ion Ionic compounds are named by identifying the cation and the ation The word 39ion39 is not used No numeric prefixes are used 0 K2504 Potassium Sulfate o CRBrrChromiumUII Bromide Chem 101 notes 91014 Covalent bonds two atoms share a pair of electros between them section 41 Main group elements do this to achieve a noble gas electron configuration An element will form one bond for each unpaired electron in its dot structure 42 0H 391 oO 392 0C 394 Know the seven elements that exist as diatomic molecules 0 H2N2021L quot2Clz37quot212 41 0 BrINClHOF Hydrogen Fluorine Oxygen Nitrogen H H F F O O N N HH OO HH FF NN not finished not finished not finished not finished Concepts 0 Single double and triple bonds 43 o Bonding pairs vs lone pairs 46 0 Molecular formula structural formulas 46 0 Lewis structures 46 47 Ammonia Molecularformula Structuralformula Lewisstructure NH3 HH HNH H H Polar Covalent Bond section 49 The sharing is unequal The electrons are more attracted to the more electronegative atom page 120 giving it a partial negative charge There is a partial positive charge on the other atom A polar bond is indicated with partial charges aa or with a polarity arrow i Drawing molecules rules 0 No unpaired electrons in the moleculeion 0 Each atom in the molecule must have eight valence electrons the octet rule H only gets two B settles for six P and S can have more 0 Carbon will form long chains Other atoms do not 0 Do not form OO bonds unless you have no other choice Don t form long chains of oxygen atoms 0 Fluorine does not make double bonds ever 0 An atom will tend to form one covalent bond for each unpaired electron in its dot symbol water H20 tetrafluoromethane CF4 phosphorus trichloride PC3 methanal CHZO carbon dioxide C02 C2H60 Acetic acid can be written as HC2H302 or as CH3COOH he second form is the condensed structure Chem 101 notes 91214 0 Isomer different molecules with the same molecular formula H H H H HCCOH HCOCH H H H H Ethanol Dimethyl ether 0 Condensed structures 0 Ethanol CH3CH20H o Dimethyl ether CH3OCH3 o Acetic acid can be written as HC2H302 or CH3COOH as The second form is the condensed structure 0 Draw the Lewis structure of acetic acid H O HCCOH H 0 Drawing Lewis structures page 10 0 Carbon Monoxide I CC I 4e6e10e I C0 0 Perchlorate ion I C104 7e46e1e32e o Nitrate ion N037 5e36e1e24e CNC5 39 C NC CNC 0 O 0 o Resonance structures structures with the same sequence of atoms but different bonding patterns o If resonance exists you must draw all possible structure that obey the octet rule 0 Sulfur dioxide o 502 I 6e26e18e I CSC CSC o Exceptions to the octet rule 0 BF3 I 3e37e24e I FBF I F I Boron accepts only 6 e because fluorine don t not do double bonds 0 BeClz I 2e27e16e I ClBeCl I Beryllium accepts only 4 e 0 Molecules and polyatomic ion can be classified by AXE type AXnEm 0 n the number of bonding groups around the central atom aby bond single double or triple is one bonding group 0 m the number of lone pairs on the central atomquotC Chem 101 notes 91514 0 VSEPR theory Groups of valence electrons around an atom will tend to stay as far apart from each other as possible 0 Geometry is the arrangement of electron groups around the central atom 0 Shape molecular shape the arrangement of atoms or bonds around the central atom Your book calls this molecular geometry just to be confusing TABLE 42 Molecular Geometry Around Atoms with 2 3 and 4 Charge Clouds NUMBER TOTAL MOLECULAR NUMBER OF LONE NUMBER OF GEOMETRY or BONDS PAIRS CHARGE CLOUDS SHAPE x E geomeuy 2 0 2 linear m Linear tmzoual planan 3 0 5 Planar 3 mom planar tnangularl I p 4 39 Bent lt h 0 Tetrahedral m39gonal pyramid Pyramidal 3 1 4 tetrahedral e L Bent 5 4 to N 0 Polar Molecule A molecule that has a positive end and a negative end 0 A molecule will be polar if it possesses polar bonds and is asymmetric about the central atom In symmetric molecules the polar bonds are positioned so that the polarities oppose each other and cancel Such molecules are nonpolar even though they have polar bonds Chem 101 notes 92214 0 Recall laboratory worksheet 1 0 You are expected to know the metric units and prefixes see the background worksheet 1 and table 16 on page 17 0 Your are expected to know how to express and read numbers in scientific notation see section 110 o Calculator check 0 Evaluate the following expression 567 x 103 988 x 10 6 573887 or 573887 x 102 o Uncertainty in measurements all measuring devices are read to 1 decimal place beyond the smallest demarcates unit on the device This line is 936 cm 0 This measurement has 3significant figures 0 Rules for this can be found on page 20 of textbook 0 Section 19 rule 4page 20 is wishywashy o Rule4 trailing zeros are only significant If the decimal point is shown 0 23000 kg two significant figures 0 23000 kg has five significant figures 0 2300000 kg has seven significant figures 0 f wanted to write 23000 kg to four significant figures how could I do that I 2300 x 104Kg 0 00005060 g has A significant figures I 5060 x 10394 g 0 General rule for problems involving math 0 All numbers must have units shown 0 Don t worry about sig figs until you have an answer to the question 0 DO NOT round intermediate values as you go Your calculator keeps all the digits significant or not Take advantage of that o If you find all you need to write down an intermediate value always keep 2 or 3 more digits than you will need in the end 0 Write the final answer with all the digits first Then round it to the correct number of sig figs and draw a circle or box around that 0 Remember UNITS ON ALL NUMBERS o A room has been found to measure 9878m long 4023m wide and 3955m high What is the volume of this room in cubic metersm3 o 9878m x 4023m X 3955m 1571685m3 o How well do we know the volume 0 All measurements have a degree of uncertainty I Minimum possible value o 9877m x 4022m x 3954m 1570738m3 I Maximum possible volume 0 9879m x 4024m x 3956m 1572632m3 The volume is 1570738m3 to 1572632m3 An easier way rule 1 on page 24 I 1572m3 OO o Uncertainty in additionsubtraction operations rule 2 on page 24 I 9873 g i 01g 10378 mL i 01 mL I 4044 g i 001g 9634 mL i 01 mL I 1612 g i 01g 744 mL i 02 mL I 0003 g i 0019 I 118397 g 22g 0 Note the number of significant figures in the result of an addition or subtraction operation may be different from the number of significant figures in any of the original values Chem 101 notes 91914 The periodic table Chapter 2 sections 45 Understand the terms period and group Know the named groups and areas on the table Identify the halogen in period 4 Periodic trends atomic radii Atoms get larger as you move down a group or right to left in a period More trends chapter 3 section 2 First ionization energies and electron affinities increase as the atoms get smaller Cation a positively charged ion The atom has lost electrons Metals form cations Anion a negatively charged ion The atom has gained electrons Nonmetals form anions Chem 101 notes 92214 0 Recall laboratory worksheet 1 0 You are expected to know the metric units and prefixes see the background worksheet 1 and table 16 on page 17 0 Your are expected to know how to express and read numbers in scientific notation see section 110 o Calculator check 0 Evaluate the following expression 567 x 103 988 x 10 6 573887 or 573887 x 102 o Uncertainty in measurements all measuring devices are read to 1 decimal place beyond the smallest demarcates unit on the device This line is 936 cm 0 This measurement has isignificant figures 0 Rules for this can be found on page 20 of textbook 0 Section 19 rule 4page 20 is wishywashy o Rule4 trailing zeros are only significant If the decimal point is shown 0 23000 kg two significant figures 0 23000 kg has five significant figures 0 2300000 kg has seven significant figures 0 f wanted to write 23000 kg to four significant figures how could I do that 2300 x 104Kg 0 00005060 g has A significant figures I 5060 x 10394 g 0 General rule for problems involving math 0 All numbers must have units shown 0 Don t worry about sig figs until you have an answer to the question 0 DO NOT round intermediate values as you go Your calculator keeps all the digits significant or not Take advantage of that o If you find all you need to write down an intermediate value always keep 2 or 3 more digits than you will need in the end 0 Write the final answer with all the digits first Then round it to the correct number of sig figs and draw a circle or box around that 0 Remember UNITS ON ALL NUMBERS o A room has been found to measure 9878m long 4023m wide and 3955m high What is the volume of this room in cubic metersm3 o 9878m x 4023m X 3955m 1571685m3 o How well do we know the volume 0 All measurements have a degree of uncertainty I Minimum possible value o 9877m x 4022m x 3954m 1570738m3 I Maximum possible volume 0 9879m x 4024m x 3956m 1572632m3 The volume is 1570738m3 to 1572632m3 An easier way rule 1 on page 24 OO I 1572m3 Uncertainty in additionsubtraction operations rule 2 on page 24 I 9873 g i 01g 10378 mL i 01 mL I 4044 g i 001g 9634 mL i 01 mL I 1612 g i 01g 744 mL i 02 mL I 0003 g i 0019 I 118397 g 22g Note the number of significant figures in the result of an addition or subtraction operation may be different from the number of significant figures in any of the original values Chem 101 notes 92914 0 Temperature is a measure of the average kinetic energy of the particles atoms molecules ions in a substance 0 The higher the temperature the faster these particles are moving 0 To make particles move faster you must give them energy Energy units see section 113 o calories cal joules J food calories Cal 1000 cal 4184 0 If 2000 cal of energy are given to 4000 g of metal X the temperature goes up by 180 C 0 If 2000 cal of energy are given to 2000 g of metal X how much will the temperature go up 2000 cal c 4000 g 180 c 2000 cal c 2000 g x c c 4000g 180 c c 2000 g x c 40009 180 c 360 0C 20009 For a given substance ener gy q a constant mass temperature change mAT o This constant is called the specific heat c o What is the specific heat of metal X q 200cal cal 00277778 mAT 40009180 c g c 0 Metal X has a specific heat of 00278 calgEC 0 Metal Y has a specific heat of 03056 calgEC 0 Metal 2 has a specific heat of 01074 calg C o 500 cal of heat are applied to 1000g blocks of each metal at an initial temp of 250 C Rank the metals in terms of increasing final temperature Metal Y lt Metal 2 lt Metal x o q csmeAT o The specific heat of water is 4184 Jg C or 1 calg C These are exact values How many kcal are required to raise the temperature of 5623 g of water from 223 C to 800 C cal q C5 m AT 2 100 0C 562g 800 c 223 C 32444 71 l 1Kcal 32 44471K l ca 1000cal ca 2 324 Real 0 Silver has a specific heat of 00563 calg C If 8320 cal of heat energy are applied to a sample of silver and the temperature changes from 234 C to 487 C what is the mass of the sample of silver q 8320cal CsAT 005630611g 5841097g 5849 m o The specific heat of iron is 01074 calg C A sample of iron with a mass of 1568g is heated to raise its temperature from 323EC to 1139EC How many calories are required for this process q 2 CS m AT 2 0107430391g 0C 1569g 1139 C 323 C 137417 cal 137 x 103cal or 137 Kcal 0 2000 cal of heat are added to a 5500 g block of iron at an initial temperature of 325 C What isthe final temperature of the iron q 2000cal Cs m 01074 calg C 5300g AT Tf Tl Tf Tl AT 325c 338581c 663581c 664c AT 2 338581 C Chem 101 notes 101 14 A solid that forms when two solutions are mixed is called a precipitate ppt To find the products of a precipitation reaction simply have the cations and anions switch partners To find the identity of the precipitate consult the solubility rules Write equations for the following reactions A solution of iron chloride and a solution of sodium hydroxide are mixed 0 FeClsaq NaOHaq gt FeOH2S 2NaC1aq A solution of sodium phosphate and a solution of nickel nitrate are mixed 0 Na3PO4aq NiN32aq gt 6NaN03aq Ni3 PO42S A solution of sodium sulfate is mixed with a solution of copper nitrate o Na3504aq CuNO32aq gt 2NaN03aq CuSO4aq Neutralization reactions An acid and a base a hydroxide react to form water and a salt The reaction of solutions of hydrobromic acid and barium hydroxide o HBraq BaOH2aq gt 2H20e BaBr2aq The reaction of solutions of sulfuric acid and potassium hydroxide o HZSO4aq 2KOHaq gt ZHZOG KZSO4aq Acids and carbonates or hydrogen carbonates form water carbon dioxide and a salt 0 HN03aq K2C03s gt H2C03aq KN03aq o H2C03aq gt HZCOG CO2 S o HNO3aq K2C03s gt HZCOG C056 ZKNO3 This is a standard chemical equation 0 2 AgN03aq K3Cr04aq AgCrOs 2 KNOW o Ionic equations Dissociate all aqueous ions I 2 Cr04aqquotquotquotquot Chem 101 notes 106 14 1 Which sample contains more atoms 1000 g of iron or 1000 g of carbon gt There are more C atoms C atoms are smaller and weigh lass then Fe atoms so it takes more C atoms to make 10000g 2 The atomic weights are the average mass of atom of that element given in atomic mass units amu 1 amu 166054x103924g a How many grams of iron have the same number of atoms as 12011 g of carbon 55847g Fe 0 60221 1023 atoms of any element has a mass equal to that element s atomic weight in grams 0 That is a useful number So useful that we give that number a name the mole 0 Why give it a name quota mole is a lot easier to say and write than quot6022x1023quot 0 One mole of any atom has a mass of that atoms atomic weight in grams Chem 101 Notes 10814 What is the mass of one mole of magnesium o 2430g Another unit for the atomic weight is gmole What is the mass of 0003500 mole of carbon 12019 0 0003500 mol m 00420359 What is the mass of one mole of carbon monoxide 0 CO 0 12019mol 16009 28019mol o mol of CD has a mass of molar mass the mass of one mole of a compound is equal to the sum of the atomic weights of the component atoms What is the molar mass of iron oxide 0 F6203 o 2 55859mol 3 16009mol 156709mol When calculating molar masses use the rules for addition to determine significant figures What is the mass of 2545 mole of sucrose C12H22011 o 8711g is the answer 9 g g g 0 121201 mol221008 mol111600 mol 342269 mol 0 2545m0l 3422969 87114323 1mol How many moles of silver nitrate are in 1000 g of silver nitrate o AgN03 g g g g 0 10787 471101 1 1401 mol 3 1600 mol 16988 mol 0 1000g 169229 0058865 mol 0 With sig figs 005887mol What mass of carbon monoxide is required to react with 5000g of iron oxide F6203 S 3 C0 g gt ZFe l 3 C02 g There are three steps to answering a stoichiometry question 1 Convert the mass you are given to moles 5000gF8203 313087m0lF8203 159709 2 Find the moles of the other substance that will react with what you were given using the mole ratio from that balanced chemical equation 3 13087 IF 0 3 moz C0 9 39261 lCO mo 62 3 1 mol F6203 m0 3 Convert moles to mass 2801g 939261mol C0 263087g 1 mol 2631g of C0 are requried mole mnl l39 x Xmolar mass ratlo mass mass of A moles A mules B mass of B 1quotFrom the Balanced Chemical Equation C12H220113 K003 l C02 9 H20 9 KCl 3 0 Identify the element oxidized the element reduced the oxidizing agent and the reducing agent 0 C is oxidized 6 gt 4 0 CI is reduced 5 gt 1 o The oxidizing agent is KC103 o The reducing agent is C12H22011 0 Balance the equation C12H22011s 8KClO3 l gt 12C02 g 11H20 g 8KCl s o If the gummi bear contains 2679 g of sucrose what mass of KCIO is required 1 mol 0 m01C12H22011 342216g 8molK103 o 000782639 mol C12H22011 m o KCl03 g 9 9 g 3910 ol3545 Ol31600 01 12253 mol 0 00626125 mol KCl03 135319 7673159 g 0 With sig figd 7673 g KCl03 00626125 mol KC103 o The chart a method for organizing calculations of chemical quantities molemass calculations 1 A balanced chemical equation is required 2 The chart should have a column for each reaction component and three rows quotmass quotmolar mass quotmolesquot from top to bottom 3 Molar masses are calculated from the formula and the atomic weights 4 To move down a column divide To move up a column multiply 5 Movement from column to column is allowed only in the bottom row moles The coefficients from the balanced equation are used to convert moles of one substance to moles of another substance C12H22011 s KCIOB I gt C02 g H20 g KCI s mass molar mass moles Chem notes 101014 0 Elemental silicon can be produced by reacting silicon tetrachloride with magnesium metal 0 Predict the other product write and balance an equation for this process 0 SiCl4l 2Mgs gt Sis 2MgCl2s o If I had 5000kg of SiCl and 5000g of Mg could I make 5000g of Si If not how much Si can I make Will anything be left over What and how much SiCl4 2809 gmol 4 3545 gmol 16984gm01 1 mol SiCl4 1 mol Si 2809g 16989 g 1 molSiCl4 1 mol 5000 g SiCl4 8267114g Si 1 mol Mg 1 mol Si 2809g Si 2430g Zmol Mg 1 mol No I cannot make 500g of Si I do not have enough Mg I can make 28900 g of Si There will be SiCl4 left after the reaction How much 1molMg 1molSiCl4 16989gSiCl4 5000 M 2174784 S39Cl 39llb d g 9 2430g 3m0lMg 1mol g l 4W1 euse SOOO q 174784 q 325216g Sig fig313252g of SiCl4 willremainl SOOOgMg 289918 g Si o limiting reactant limiting reagent It is possible to determine the limiting reactant if the masses of all the reactants are known 1 Choose a product of the reaction any of the products will do 2 Calculate the mass of this product that can be made from each reactant 3 The reactant that makes the least amount of product is the limiting reactant The mass of product calculated from the limiting reactant is the maximum mass of product that can be made 0 Balance the reaction between phosphorus and oxygen 1343 5029 P4010 5 How much phosphorus pentoxide P O can be prepared by the reaction of 5505g of white phosphorus with 6540g of oxygen Atomic weights P 3097gmol O 1600gmol 550g p4 P 4010 4 3097 10 1600 28388 P 4 4 3097 12388 1molP 4 1 mol P 4010 293889 32009 5m0102 1mol 1 mol 02 1 mol P 4010 293889 3200g Smolo2 1mol l1160gP 4010 will be made l 5505P 4 1261g 6540g02 11604g Chem Notes 101314 2H2 9 029 gt 2H20g o Endothermic or exothermic o Endothermic o The heat energy released or absorbed by a reaction is called the heat of reaction or the enthalpy change and is represented by the symbol AH 0 Reactions tend to occur if there is an overall release of energy during the reaction 0 Being exothermic AH is negative is one way that a reaction can release energy 2C2H69 702 9 4C02 9 6H209 AH 6825 kcal o Is this reaction exothermic or endothermic o Exothermic I It s a combustion reaction and if you are burning anything it is always exothermic o How much heat energy in kcal is produced when 4500g of ethane is burned C2H6 2 12019mol 6 10089mol 300689mol 1 molC2H6 6825 kcal 4500 g C2H6 2 5107174 kcal 30068g Zmol C H With sig figs 5107 kcal o What mass of oxygen is consumed by the combustion of ethane if 12500 kcal of heat are produced 1250 Ok i 7 moz 02 323900 g 410 2564 ca 6825 kcal 1 mol 02 9 With sig figs 2 l4103g of 02will be consumed l 0 11834 g of ammonium nitrate are added to 1500 mL of water at 2233 C The temperature of the solution produced is 1719 C The specific heat of the solution is 0980 calg C The density of the solution is 0997701 gmL What is the enthalpy of solution for ammonium nitrate in kcalmol q cq m AT 0999701 g m 1500mL 14965515 g 1 mL 0980 cal q solurion W 14965515 g 1719 C 2233 C 2 753843 kcal 753 843 l 1 kcal 0753843 k l ca 1000 cal ca q reaction 2 q solution 2 0753843 kcal 0753843 kcal NH4N03 2 14019mol 4 10089mol 3 16009mol 800529mol 11834 0147829 lNH N0 9 80052g m0 4 3 q 0753843 kcal k 4 cal m 0147829 mol 5 099 3 mol With Sig figs 2 510 kcalquotml AH 2 NH4SCNSBa0H28 H20s gt 2NH3 g BaSCN2aq 10H20l o Endothermic or exothermic o Endothermic I It got cold if heat it exothermic then when a reaction gets cold it is endothermic o Entropy a measure of the degree of disorder in a system A change in entropy is designated by the symbol AS 0 Energy is dispersed as entropy increases 0 How do you judge a change in entropy o solids lt liquids lt solutions lt gasses o more particles more entropy Chem notes 101514 0 Is AS positive or negative 2Hgl 02g gt 2Hg0s AS is NaCls gt Naaq Cl39aq 45139s H2504aq Ba0H2aq gt 2H20l Ba504s 45139s C3H8g 5029 3C02C9 4H20g 45139s o All four reactions are spontaneous What is the sign of AG 0 Negative 0 What is the sign of AH for each reaction 2Hgl 02 g gt 2Hg0s AS is AG is AH must be NaCls gt Naaq Cl39aq AS 139s AG 139s AH can be eitber or AH must be less tben TAS H2504aq Ba0H2aq gt 2H20l Ba504s As is A G 139s AH must be negative C3H8g 502 g 3602 g 4H20g As 139s A G 139s AH is it s a combustion reaction it is always nega title 0 The total energy all types released or absorbed by the system is called the free energy change and is represented by the symbol AG 0 The relationship of the change in free energy to the changes in entropy and enthalpy are given by the equation AG AH TAS 0 Where T is the temperature in Kelvin I K C27315 o If AG is negative the reaction is spontaneous o The reactions on the previous slide are all spontaneous at 25 C 0 What is the sign of AG for these reactions 0 If AS is 10 calK and T is 100K then TAS is 1000cal and TAS is 1000cal in order to make AG negative AH must be less then 1000cal 2H2g 029 ZHZOCQ ALSO 2121 calK AHO 11560kcal cal 1 kcal kcal 2121 1000cal O021217 o What is the value of AG0 for the reaction of hydrogen and oxygen at 25 C 0 AG 15560kcal 28915k 002121 10928kcal o Is the reaction between hydrogen and oxygen spontaneous at 250 C 0 Yes 0 Will it be spontaneous at all temperatures I No 0 What is AGo for H2 02 at 60000K kcal AG 2 1556kcal 60000k OOZlZlT 1166kcal Sign of AH Sign of AS When is AG negative and the reaction spontaneous Negative Negative Spontaneous at low Temperatures Positive Positive Spontaneous at high Temperatures Negative Positive Spontaneous at all Temperatures Positive Negative Spontaneous at no Temperatures never 0 Reactions occur when molecules atoms collide but not all collisions result in a reaction taking place 1 Molecules must collide with sufficient energy to react 2 The molecules must be oriented in the correct manner for the reaction to occur 0 Thus reactions occur faster when 0 the reactant concentration is increased 0 the temperature is raised 0 a catalyst is used 0 The combination of the minimum collision energy required for a reaction and the difficulty in obtaining the correct orientation for a reaction can be considered to form an energy barrier to the reaction 0 The reactants when they collide must possess enough energy to overcome this barrier in order for the reaction to proceed Chem notes 101714 0 This minimum energy a of collision is called the activation energy and represented by Ea o The activation energy is often depicted in a reaction energy diagram yaxis gtG xaxis gtreaction progress AG is the reaction is endergonic Reaction progress AG is the reaction is exergonic m o OuNztext draws reaction en rgy diagrams using free energy G on the yaxis They can also be drawn using enthalpy H or just e ergy E on the yaxis Note the value All or does not affect therate the reaction Only Ea affects this Hl Hill NH EEEE E ia A Wll UHH 3 5H g 31 u m mw mumm a quots H a e s s a iaai fn M WHH a anquot Luit1 t zbw uu H H H Luauquot Luna mam H H H 39 H H H N If the concentrations and temperature is the same which reaction is faster A gtB is faster it has a lower Ea o Catalysts a catalyst is a substance that increases the rate of a reaction but is not changed by the reaction it is not a reactant o Catalysts participate in the reaction but are regenerated in the course of the reaction Catalysts provide an alternate reaction path that has a lower activation energy than the original uncatalyzed pathway Many catalysts work by constraining the orientation of the reactant molecules so a larger percentage of the collisions will result in a reaction Catalyst do not appear in the chemical equation Catalysts do not shift the equilibrium C4H306392aq 5H20aq gt 3C 02 g C 03 0161 7H20l AH 17656 k Ea very large lt uncatalyzed CAH305T2GCI I 3C0 C02 a 7H 01 Reaction progress X 2 concentration of X in mol L If reactants 2 products which reaction will be faster the forward reaction or the reverse reaction 0 The forward reactrion is faster it has a lower Ea As the reaction runs reactants will increase and products will decrease So rate fwd will decrease and rate rev will increase Eventually rate fwd 2 ate rev This is called equilibrium reactants amp products are no longer changing At equilibrium reactants g products put lt or gt in the blank Equilibrium The situation when the rate of the forward reaction equals the rate of the reverse reaction Equilibrium equations section 78 For a generic reaction in equilibrium aA aqbB aq cC aqdD aq K is the equilibrium constant If K gt 1 the reaction is product favored If K lt 1 the reaction is reactant favored K is always positive Pure solids and liquids have a constant concentration they do not appear in the equilibrium equations Write the equilibrium equations for 4NH4g 5029 4N0g 6H20g N 0 H206 N H2 025 Chem notes 102014 Write the equilibrium equations for HC0339aq H30aq r 2H20l C02g H202 HC0 H30 2CS 029 ZCOCCJ Consider this reaction system at equilibrium C0Clzg x CO 9 C12 9 AH 995k In which direction will the equilibrium shift if Clz g is added Shift toward the reactants 60029 C0 g C12 9 If the something is add It pushed the equilibrium in the other direction CO g is removed shift towards the products 60029 x CO 9 C12 9 R If something is removed The equilibrium is pulled in that direction COClz g is added Shifts toward the product C0Cl2g heat C0 g Clz g R Raising the temp is adding heat Adding a reactant pushes the equilibrium toward products The temperature is raised shift towards the products The volume is decreased shift towards the reactants Chapter 8 Classify the following phase changes as endothermic or exothermic o Freezingxlx sublimationxlx vaporizationxl Exothermic Endothermic Endothermic Consider a solid melting AH is AS is Is melting spontaneous at high T or low T Remember if AG AH TAS lt 0 then the process is spontaneous f AH lt TAS the substance melts f AH gt TAS the substance freezes At the melting point boiling point or sublimation point the two phases are in equilibrium AG 0 AH TAS The intermolecular forces present in the compound determine the temperature at which phase transitions occur The stronger the intermolecular force the higher the temperature at which the transition occurs The intermolecular forces weakest to strongest London dispersion forces all molecules Dipoledipole forces polar molecules Hydrogen bonds molecules with NH OH or HF R H H Z this is a hydrogen bond IqlI I this is the bond to hydrogen Ionic bonds between cations and anions Identify the strongest intermolecular force operating between molecules of the following usubstances a 502 b C02 c NH3 Dipoledipole London dispersion force Hbond d SiCl4 e SFZ f CH3CH3 London dispersion force Dipoledipole London dispersion force g NaCH3C00 h PCl3 Ionic bonds Dipoledipole The strongest IMF is Is the com ound ionic Yes gt ionic bonds No Does it have NH OH or HF bonds Yes gt hydrogen bonds No Is the compound polar Yes gt dipoledipole forces No l l London dIsperSIon forces Chem 101 notes 1022 14 o Predict order of the boiling points of the following substances list them from lowest boiling to highest boiling o CH3F CH30H CH3CH3 Lowest bp highest bp CH3CH3 lt CH3F lt CH30H o N2 503 Ar All have London dispersion forces which increase with molecular size molar mass Lowest bp highest bp I N2 lt AT lt 503 0 Compound 1 Compound 2 Compound 3 i CH3 11 CH3 CH3 Cl CH3 CH3 CH2 CH2 NH2 CH3 CH3 0 Compound 2ltCompound 1ltCompound 3 0 Compound A Compound B Compound C CH3 CH2 CH2 CH CH2 CHz CHz CHz CHz CHz CH3 CH3 C CTI CH3 CH3 CH3 CH3 0 All have the London dispersion force which increase with molecular surface area 0 Compound CltCompound AltCompound B 0 Know the kinetic molecular theory sec 83 o How does it explain gas pressure 0 Last bullet point on page 221 o What are the units of pressure section 84 0 Know how gasses respond to changes in volume V temperature T and pressure P 0 Sections 8589 The Gas Laws 0 Section 810 The Ideal Gas Law PV R PV nRT nT R 00820575me 623637Lt quot molK molK Tmust be in KelvinTK T C 27315 A sample of chlorine gas sealed in a rigid 2000 L container has a pressure of 5500 torr at 250 C How many moles of chlorine are in the container PV 0 n RT 5500 torr2000L 0591597m0l 623637 L t0 29815K molK o with Sig figs 05916 mol C12 A sample of argon gas sealed in a rigid 2000 L container has a pressure of 5500 torr at 250 C How many moles of argon are in the container 0 05916 mol1r o All gasses act the same Chem 101 notes 1024 14 o 1700g of nitrogen gas are sealed in a rigid 3500 L container at a temperature of 750 C What is the pressure inside the container in atm P nRT 1mol 1700gN2 28 02g 0606709493 mol N2 0606709493 mol 00820575 L 3613 75 27315K P 3 5002quot 49521946 atm With sig figs its 4952 atm 0 When 1777 g of a compound are vaporized the gas occupies 6287 mL at a pressure of 09274 atm and a temperature of 873 C What is the molar mass of the compound 06587L 09274 atm n 0019712751 mol L atm g g 901446978 0019712751 mol TROl With sig figs its 9014gm0l K S 2H20 l 2KOH aq H2 g o 3500g of potassium metal react with excess water At 237 C and 0900 atm what volume of hydrogen gas is produced 2825 K 1mm 1mm 0361253167 lH g 3910 ZmolK m0 0361253167 mol 0820575 237 27315K mol K 09083 atm V 9688080072L With sig figs its 9688L Iquot mm quot ET 9 P llf39ljiluilrl me If gag 1 31 Filllll l iif E515 Hf Imi lr 1115155 L 1113155 ofquot 131 molea A 39 foef cimm From the Balanced 13116111161 Equation lll 315 EFECE f mum 1113155 If 1111101555 2F6253S 902g gt 6502g 2F 203S o What mass of iron oxide will be produced by reaction of 5250 L of oxygen at 750C and 1200 atm assume excess iron sulfide 119203 2 5585 9mol 3 1600 gm 15970 gmoz 5250l 1200atm L atm 0820575mol K 750 27315K 2 mol F6203 159709 9 m0l03 1 molFeZO3 with Sig figs 7826gF6203 n 220524m0102 220524mol 02 7826151861gF3203 A rigid 246 L container at 300 K holds 100 mole of oxygen and 100 mole of nitrogen What is the pressure in atm atm L nRT 200mol 00820575W 300 ol P V 24611 20014atm How much of this pressure is due to the oxygen 12 or 50 What would the pressure be if the container only held 1000 mole of oxygen at 300K 100m0l 00820575m 300K mol K 2466 What would the pressure be if the container only held 1000 mole of nitrogen at 300K The pressure exerted by a single gas in an mixture of gasses is called the partial pressure of that gas The total pressure equals the sum of the partial pressures of all the gasses present 0 Ptotalsz2P02 A mixture with a total pressure of 8000 torr is 600 hydrogen and 400 nitrogen by volume What are the partial pressures of each gas PH2 0600 8000t0rr 4800t0rr 100atm Chem 101 notes 1027 14 Section 812 o What are vapor pressure and surface tension 0 How do intermolecular forces affect them 0 The stronger the intermolecular forces the wearer the vapor pressure 0 What is the connection between vapor pressure and the boiling point 0 Which substance is likely to have a higher vapor pressure 0 12 or Brz I Br has weaker b dispersion forces and the higher vapor pressure 0 H20 or H25 I H0 is hbond and HS is diplediple I HS has the higher vapor pressure 0 C02 or HCl I CC is London force and HCl is diplediple I CD has the higher vapor pressure 0 CH30CH3 or CH3NHCH3 Section 815 0 When a solid melts or a liquid boils the temperature remains constant even though heat energy is being added to the substance Why 0 The energy is used to change the relative position of the molecules potential energy not to make the mulecules move faster there is no in kinetic energy 0 Heating curve for water T c 1000 400 Heat added kcalg 0 Heat of vaporization AHvap5386 calg for water 0 Boiling 0 Heat of fusion AHfus 7986 calg for water 0 melting 0 Calculate the heat involved when 1500 g of steam condense to liquid water at 1000 C 5386cal 1500g T 80790cal 8079 kcal Section 92 The Solution Process 0 Solubility is determined by the interaction of three forces 0 The IMFs in the solute which must be broken 0 The IMFs in the solvent which must be broken The interactions between the solute and the solvent which are formed Section 93 Hydrates We have mentioned waters of hydration before The text describes them here Sections 9496 Most materials have a limit to their solubility in a given solvent The solubility is usually expressed in g of solute per 100mL of solvent In a saturated solution the dissolved solute is in equilibrium with the pure solute Supersaturated solutions have more solute in solution than is stable not at equilibrium Most solid solutes become more soluble as the temperature increases there are exceptions All gasses become lei soluble as the temperature increases Gasses become more soluble as the partial pressure of the gas increases The solubility of C02 in water at 100 atm and 25 C is 0030 M What is the solubility of C02 at 300 atm and 25 C Chem 101 notes 1029 14 Molarity M Also called molar concentration moles of solute per liter of solution See section 97 molsolute LSoluti0n o How many moles of perchloric acid are present in 5900 mL of 08762 M perchloric acid 590 0 L M 3908762m01 0 516958 I 39 m 1000mL 1L 39 m0 05170 mol HCl04 o What volume of a 3587 M solution of ammonia contains 06000 mole of ammonia 0 6000 1 1L 1000mL 167 270 l m0 3587m0l 1L m0 1673 mL 0 6023g of Na2C03 are dissolved in water to produce a solution with a volume of 4000mL What is the concentration of this solution in molarity 2 2299 1201 3 1600 10599 60 23 1mm 0 568261157 l g 10599g m0 0156826115717101 1000mL 1 420652892m01 4000mL 1L L 1421 M Na2C03 Section 98 Dilutions o In dilutions the amount of solute does not change Only the volume of the solution does 0 If 2000 mL of the Na2C03 solution is diluted to a final volume of 1500 mL what is the concentration of the new dilute solution 200 0 L M 1421mm 0 02842 I m 1000 1L m0 mL 002842m0l 1000mL 0 189466671 1500mL 1L 39 01895M NaZCOZ o What volume of a 180 M solution of sulfuric acid must be diluted to produce 8000 mL of a 07500M solution 800000 L M 0750077101 06000 I 39 m 1000mL 1L 39 M 06000 I L 1000mL 33 3333 L m0 180m0l 1L m 333mL o What volume of 2358 M HCl is required to react with 1000g of calcium 2 HCl aq Cas gt CaCl2aq H2g 100 0 C 1 moz ca 2 moz HCl 0 499002 lHCl g a 40089 1 mol Ca m0 0 499002 lHCl 1L 1000mL 39 m 2358 1L 2116mL 2116208mL milling 3931 amttc of 55 A E i Jrrlnllmult I39llales 31h Q IITI39IEEIEH ii ll l lili allquot all I f39ttnoenlzr litm HF Ii M L39 tl t ltf l ion trill939s M E j J EM r mu rm u 777777777777777777777777777777777 H nlutmn 15 Q39me the i ll ll39li l Slientii i il Emmett What mass of barium sulfate will be formed when 2250 mL of 03562 M sulfuric acid and 4260 mL of 01925 M barium hydroxide are mixed What mass of silver carbonate will be formed when 2650 mL of 04068 M silver nitrate and 1563 mL of 06287 M sodium carbonate are mixed What mass of nickel phosphate will be formed when 2750 mL of 06829 M nickel chloride and 2562 mL of 03587 M sodium phosphate are mixed Chem 101 notes 103114 0 Compounds that do not dissociate in water are called nonelectrolytes Solutions of nonelectrolytes do not conduct electricity 0 C12H22011 S C12H22011aCI o Ionic compounds that fully dissociate in water are called strong electrolytes Solutions of electrolytes conduct electricity 0 Na2C03s gt 2Naaq C032 Classify the following as electrolytes or nonelectrolytes o C H3 0H K 0H N aC l NonElectrolytes electrolytes Electrolytes o FeCl3 H2504 CaBrz Electrolytes Electrolytes Electrolytes C6H1206 C2H602 NonElectrolytes NonElectrolytes 0 Some compounds only partially dissociate when they dissolve in water These are called weak electrolytes The most common weak electrolytes are the weak acids 0 know which 6 acids are the strong ones ch 10 o Colligative properties 0 All of these phenomena depend upon the number of solute particles but not their identity 0 So to compare solutions you have to calculate the effective concentration in particles ions 0 vapor pressure depression 0 boiling point elevation o freezing point depression 0 Osmotic pressure I use concentration units of molality m this is moles of solute per kg of solvent 0 Rank these solutions in order of increasing boiling point 0 0200m CH30H 0100m CaClz 0075m KN03 I 0200m CH30H 1 0200m I 0100m CaClz 3 0300m I 0075m KN03 2 0150m o 0 075m KN03 gt 0200m CH30H gt 0100m CaClz 0 Rank these solutions in order of increasing freezing point 0 0075m KN03 gt 0200m CH30H gt 0100m CaClz Osmosis see section 912 o If two solutions are separated by a semipermeable membrane water will tend to flow through the membrane into the quotmore concentrated solution 0 In this case the concentration is moles of particles per L of solution 0 The pressure required to prevent pure water from flowing through a semipermeable membrane into a solution is called the osmotic pressure of the solution 0 In which direction will the water flow w sempen39iueble i membrane w m 7 r a h s ahi v 39 39 r 39eeeeeeeeeeeeemgwgeeeee 39 quot I 5 I r awahm a eeee k t hll 05mm sulfate ammonium pemh lurate o 0600M K2504 3 180 0500M 2 100 o More counteracted lt water flows left Which solution will have the higher osmotic pressure at 250EC 2500g KCI in 6000 mL water 5000g C2H602 in 7000 mL water 25 00 1molKCl Zmol ions 1 118 7 g 7455g 0600L 1 mol KCl 03 1 mol 1 mol 5000g 1151 03 62068 0700L 1 mol The C2H602 solution has a higher osmotic pressure Isotonic solutions have the same osmotic pressure as bodily fluids Chem 101 notes 11314 Haq is really H30 aq hydronium ion Acids create hydronium ions by transferring a hydrogen ion to a water molecule 0 HClg H20 gt H30aq Cl39aq Some bases produce hydroxide ion OH in water by accepting a hydrogen ion from water 0 NH3g gt NH3aq o NH3 aq H20l r NHIaq 0H39aq The Br nstedLowry AcidBase Model section 103 defines acids and bases in terms of the transfer of a hydrogen ion a proton An acid is a substance that can transfer a proton H to another substance Any substance that contains hydrogen m be an acid A base is a substance that can accept a proton from another substance Any substance that has a lone pair of electrons be a base What happens if you put the acetate ion in solution as sodium acetate for example 0 NaC2H302S gt Na aq C2H302 aq o C2H302 aq H20l HC2H302aq H0 aq Acetate ion is a base It is the conjugate base of acetic acid What happens if you put ammonium chloride in solution 0 NH4Cls gt NH4 aq Cl aq o NH4 aq H20l r NH3aq H30 aq Ammonium ion is an acid It is the conjugate acid of ammonia What is water in the previous two reactions 0 H20 acts as an acid with C2H302 0 H20 acts as a bass with NH4 H A aq B aq A39 aq H B aq When an acid loses a proton what is left is a base When a base gains a proton it becomes an acid The acid and base related by a single proton are called a conjugate acidbase pair The acid is the protonated form The base is the unprotonated form What are the conjugate acids of these bases CH3CH2C0239 SO3 CH3CH2C02H H503 Cl039 CH33N HClO CH33NH What are the conjugate bases of these acids HCN CH32NH2 CN CH32NH H2P0439 CH30H HP04 2 CH30 An equation for the reaction of a generic acid with water would be AH aq H20 1 r A aq H30 aq A general equilibrium expression for an acid is lA39JlHoJK AH a Ka Is the acid dissociation constant It is a measure of the strength of the acid The larger the Value of Ra the stronger the acid Strong acids have a large Ka values gt 100 Weak acids have small Ka values 01 1x10 3915 Strong acids completely transfer the acidic hydrogen to water They are strong electrolytes o HClaq H20l gt H30 aq Cl aq Weak acids only partially transfer the acidic hydrogen to water They are weak electrolytes o HC2H302aq H20l r H30 aq C2H302 aq Most strong bases are soluble hydroxide salts These are strong electrolytes o Na0HS gt Na aq 0H aq Weak bases produce hydroxide ion by accepting a hydrogen ion from water They only partially take the H from water They are weak electrolytes o NH3 aq H20l r NH4 aq 0H aq Chem 101 notes 11514 0 The stronger the acid the weaker the conjugate base The weaker the acid the stronger the conjugate base 0 H2504 is a strong acid with a Ka gt 100 0 H504 is a weak acid with K a 12 x 10392 o Ethanol CZHSOH is an ineffective acid Ka 103918 Acid Diaaaciati a Ctmatantai at REHEC acid PIECE 431M chltircacctic acid CHECIEDUH lalit l 39 39 chltiruua acid H Cl l Llama cr39t39lma rmcic acid acctic acid EHEEUGH LTIEIIIE39S hydrullimmic acid HE am hydrucyamic acid ilj l mn hydm wmic acid HF MINEquot hydrugcn ca mna lc H C 431M hydrugca mlfatc H303quot Willi hydrugcm aul tc H333 L39DEIIE39T hydraaul iiic acid H33 9111 hypcbruma ua acid H r 151MB hyp clmlum ua acid HTCIU 3401 iadic acid IllI l E l393 flu it l 39 m 39l ll i acid funnic acid H C II fl q nitraua acid I lfiquotill ll 4611quot pmpa acic acid CHECHECDDH fl dit l 39 a ulfiiiic acid Kill Ill 4 11 a ulfiiia ua acid KM H3311 l dit l 39l Section 106 The autodissociation of water 0 2H20 l r H30aq 0H39 aq 0 At 25 C H300H 100x10 14 2 KW o In pure water H30 2 0H39 2 100x10397 M o This is defined as neutral neither acid nor base o If H30 gt 100x10397 M the solution is acidic o If H30 lt 100x10397 M the solution is basic The pH scale pH log H30 log means logarithm The log of a number is the power of ten that produces that number log100x10397 7 H30 100x10397 M H30 100x10393 M H30 400x10 14M A pH 700 is neutral A pH greater than 700 is basic A pH less than 700 is acid There is also a pOH log0H39 0 pH pOH 1400 httpwwwchemfsueduchemlabchm1046courseacidbase Chem 101 notes 11714 H30 10pH What are the values of H30and 0H39 in a solution with a pH 438 H30 10 38 41687 10398M 42 10 5M 100 103914 10 H0 4I1687105 239881O M 24 10 10M Acidicbasicneutral salts o If the cation is a weak acid NHF the salt will be acidic o If the anion is a weak base conjugate of a weak acid the salt will be basic 0 Otherwise the salt is neutral 0 Cations make from alkali metals or alkaline earth metals are neither acidic or basic Classify the following salts as acidic basic or neutral NaF 0 Basic 0 F39is a weak basethe conjugate base of a weak acid HF NH4C104 o Acidic o NHF is a weak acid M92 CN 0 Basic 0 CN39is weak basethe conjugate base of HCN a weak acid KBquot 0 Neutral 0 Br39is an ineffective base the conjugate base of a strong acid HBr LiHSO4 o Acidic 0 H504 is an ineffective A solution containing a weak conjugate acidbase pair will tend to resist changes in its pH Such solutions are called buffer solutions Buffers work because acid and base forms are in equilibrium with significant concentrations of each There is always something available to release or accept hydrogen ions A H aq H20 1 r H30 aq A39 aq Strong acids and bases cannot do this because they do not reach equilibrium If both components were present in equal concentrations would a buffer form Why or why not HN02 and N0 0 no HZPO and HP0439 0 yes CH3CHZCO0H and CH3CHZC00 0 yes HCl and Cl 0 no K AHHBOI Hp39 quot H4 llC0 l111gII basgquot pH Plxa log and J pKalogKa 0 Note if HA 2 A39then pH pKa Hydrofluoric acid HF 66 10394 Hypochlorous acid HCIO 30 10398 Chloroacetic CHZClCOOH 14 10393 What is the pH of a solution that is 0250 M in HCIO and 0250M in NaClO pH pKa log30 1039s 2 752 Chem 101 notes 111014 o If the pH pKa then the protonated form acid and the unprotonated form base are present in equal concentrations o If the pH lt pKa then the protonated form dominates o If the pH gt pKa then the unprotonated form dominates o For a every 1 pH unit that the pH differs from the the concentration of the dominant form will be a factor of 10 times the concentration of the other form 0 Phenol C6H50H ha as a Ka of 10 103910 o What is the unprotonated form of phenol 0 Which form of phenol protonated or unprotonated will dominate in a solution with pH700 pH 900 pH 1000 pH1200 chem 101 notes 111214 HNO and CH CO0H are monoprotic acids H2504 a diprotic acid H3P04 is a triprotic acid NaOH and KOH are monoprotic bases Ba0H2is a diprotic base Titrations This is more stoichiometry 1793mL of a 01204M potassium hydroxide solution are required to neutralize 2500mL of a sulfuric acid solution What is the concentration of the sulfuric acid solution 2KOHaq H2504aq gt 2H20l K2504aq 01204 mol KOH 1 mol H2504 001793L 00007938 ZlmolKOH 0001079386 molH2504 m0 0043175447 10l 002500L L 00431M 1098 mL of a 02284 M solution of barium hydroxide are required to neutralize 2000 mL of a hydrobromic acid solution What is the molar concentration of the hydrobromic acid solution Br0H2aq 2HBraq gt O 01098L 02284 mol Br0H2 2 mol H31quot 0 00501664 lHB 1 L 1 mol Br0H2 quotw r 000501664 mol 02507832 mol 002000L L 0251 M 2807 mL of a 05160 M solution of nitric acid are required to neutralize 1500 mL of a strontium hydroxide solution What is the molar concentration of the strontium hydroxide solution 2HN03 aq Sr0H2aq gt 2H20l SrN03aq 05160 mol 1 mol SrN03 002807L 000724206 5 N0 3 quot 0 quot m0 2 mol 001 SOOL 0482804 L 04828M 1592 mL of a 03332 M solution of phosphoric acid are required to neutralize 1000 mL of a lithium hydroxide solution What is the molar concentration of the lithium hydroxide solution H3P04aq 3Li0Haq gt 3H20l LiP04aq O 01592L 03332 mol H3P04 3 mol Li0H 0 015913632 1 LIOH 10015913621 Tml H3P04 m0 1 m0 1 147710l 001000L 59 L 1591 M 2237 mL of a 07085 M solution of hydrochloric acid are required to neutralize 3000 mL of a sodium hydroxide solution What is the molar concentration of the sodium hydroxide solution HClaq NaC0aq gt H20l NaClaq 07085 molHCl 1mol NaOH 002237L 0015849145 mol NaOH 0015849145 1nlleCl m0 2 mol OOBOOOL 05284914 L 0 4702 mL of a 08757 M solution of potassium hydroxide are required to neutralize 7500 mL of a sulfuric acid solution What is the molar concentration of the sulfuric acid solution 2KOHaq H2504aq gt 2H20l K2504aq 08757 mol KOH 1 mol H2504 004702L 0 0121658771 ZlmolKOH 002058771m0lH2504 m0 2 mol 007500L 027450276 L Chem 101 notes 111414 Some isotopes are stable others are not Unstable isotopes undergo radioactive decay The only difference between isotopes is the number of neutrons For light elements Z 2 20 the most stable nucleus has an equal number of protons and neutrons or one more neutron than protons For heavier elements Z 21 to 83 more neutrons are required for stability For superheavy elements Z gt 83 there are no stable isotopes There seems to be greater stability in having even numbers of protons and neutrons Types of radiation 0L radiationaparticles are equivalent to the nucleus of a helium atom He 3 radiation The emission of electrons beta particles 1 esometimes writen as 1 The electron comes out of a neutron turning it into a proton Positron emission A positron is an antielectron 1 esometimes written as 23 The positron comes out of a proton turning it into a neutron Electron capture An electron falls into the nucleus It is absorbed by a proton turning it into a neutron y radiation the emission of photons electromagnetic radiation in the gamma region of the electromagnetic spectrum This is a way for the nucleus to shed extra energy after one of the other types of decay All nuclides with Z gt 83 are unstable Most decay via alpha particle emission Nuclides with too many neutrons decay via beta particle emission Nuclides with too few neutrons decay by positron emission or electron capture Equations for Nuclear reactions 0 Alpha particle emission radon222 Beta particle emission Bismuth214 Positron emission fluorine17 Electron capture Iron55 Uranium235 is bombarded by a neutron to split into zirconium96 two neutrons and one other isotope Write the equation for this 0 Iron58 and bismuth209 collide to form a superheavy isotope and a neutron Write the equation for this 0 O O O Chem 101 notes 111714 Radioactive isotopes have a halflife t1 2 This is the time required for the activity to fall to 12 of its original value For a given time interval t n is the number of ha lflives t t 12 A0 is the original activity A is the activity at time t log 4 l 39J A X E n 1 39 10L 7 Activity is directly proportional to number of atoms so number of atoms N No or the mass m me can be substituted for A A0 in any of these equations Halflive Vo 0 10000 1 5000 2 2500 3 125 60Co has a halflife of 527 yr What percentage of its original activity will a sample of 60Co have after 1581 years 1518 yr 300 half live yT39 527 half live A 10000 123 125 What percentage of its original activity will a sample of Co have after 2 years 200 yr 03795 half live yT39 537 half live A 100 1203795 76870042 14C is radioactive other common forms of carbon 12C amp 13C are not 14C undergoes beta decay with a halflife of 573gtlt10 yr 14C is created in the upper atmosphere distributed throughout all living organisms This maintains a constant 14Ctotal C ratio and a constant 14C activity in all living organisms When you die you stop exchanging carbon with the rest of the world and the ratio of 14Ctotal C slowly drops o A fragment of wood has a 14C activity of 00638 Bqg A living tree has a 14C activity of 02552 Bqg How old is the fragment of wood Bq 00638 g 0250 02552 Bqg 00638 Bqg 02592 Bqg loge 573 103 lwe 0 Activity radiation intensity is measured in becquerels Bq o A becquerel is 1 counts There is also a curie Ci This is 37 x 1010 counts per second 0 Intensity diminishes with the square of the distance from the source 0 A sample of 226Ra has an intensity of 5000kBq at a distance of 150m What is the intensity of the radiation at 700m log 200 half live 2 11460 year 11d12 12 d22 110102 5000 1507102 2 d2 700m2 o The Roentgen R measures the amount of ionization produced by radiation 0 Low energy radiation nonionizingsimply heats up the material that absorbs it 0 High energy Ionizing radiation knocks electrons out of matter forming cations and free electrons This can cause considerable damage 0 The rad is the unit of radiation energy absorbed by a target It is 00100kg o The grey Gy is the SI unit or radiation absorbed It is 1000kg So 1 Gy 100 rad 0 Even this is not sufficient to determine the biological effect of radiation This is measured with o the rem 0 dose in rems quality factor x dose in rads o The quality factor is 1 for beta particles Gamma radiation is close to this but alpha radiation has 3920 times the effect 0 The penetrating power of radiation is a lt B lt y 0 So for sources outside the body the risk posed by radiation is a lt B lt y 0 But if the radiation source is on or in the body the risk is reversed a lt B lt y 2225918 kBq Chem 101 note 111914 Organic Chemistry Chapters 1213 0 C forms 4 bonds H forms 1 bond 0 C always obeys the octet rule 0 The shape amp geometry around a C atom with 4 single bonds is Tetrahedral and the bond angle is 1095 Alkanes o Hydrocarbons with all single bonds 0 Anything other than singly bonded CC and CH is a functional group 0 See section 122 and table 121 on page 361 for a list of functional groups You need to know these Also see the concept map on page 389 o The IUPAC nomenclature system for organic molecules section 126 o Prefixes representing numbers on the table of quotstraightchain alkanes 0 Table 122 page 375 Know them 0 Representing organic structures 0 Draw the structural formula of hexane o condensed structure 0 molecular formula 0 bond formula line structure 0 Write molecular formula for the compounds with the following line structures M i W gtlt Jo Chem 101 notes 1212014 0 Isomers Compounds that have the same molecular formula but different structures 0 Isomers often have very different properties from each other because they differ in both shape and the placement of polarnonpolar bonds 0 Constitutional isomers structural isomers o Isomers that differ in the pattern of bonds and atoms in the molecule 0 Molecules can rotate freely around single bonds A large molecule with many single bonds can assume many different overall shapes These molecular shapes are called conformations They are not isomers they are conformers 0 Compounds with the formula C4H4 o HexaneCH3 CH2 CH2 CH2 CH2 CH3 0 3methylpentane o Are there more compounds with this formula 0 CH3 CH2 CH2 CH3 CH3 0 CH3 CH CH CH3 CH3 CH3 CH3 0 CH3 0 CH3 CH CH2 CH3 C H2 C H2 0 Identify each pair of structures as isomers conformers identical molecules or neither Are these molecules isomers conformers or neither CH CH 393 CH a CH CH 392 l l CH3 CH3 CH 2 CH a and CH 3 CH CH CH 3 CH CH I I on CH3 CH3 They are conformers the same compound CH3 CHg CH39 iH CH3 l CH3 I H2 H3 and CF13 9H3 CH3 CH CHE CH3 112 CH3 2 They are isomers Physical properties of hydrocarbons 0 These are nonpolar molecules So they tend to be soluble in each other and insoluble in water 0 Dispersion forces increase in strength with increasing molar mass Dispersion forces also get stronger with increasing surface area on the molecules 0 The boiling points of long chain alkanes are higher than the boiling points of highly branched alkanes of the same size 0 Cyclic alkanes tend to have higher boiling points than chain alkanes of the same size Which will have a higher boiling point hexane or 23dimethylbutane o Hexane CHS CHz CH CHI CHz CH CH3 CIH3 CI39H3 and CH3 CH CH3 CH3CH CH3 I39Hg CI HB CI H J C H CH CH3 I 39 I CHw CH CH and CHs CHCH2 CH3 quot 39 CH CH3 SH CH3 CH3 methylcyclohexane or 3ethylpentane o methylcyclohexane 223trimethylbutane or 3methylhexane o 3methylhexane 0 Both are isomers Chem 101 notes 1232014 Reactions of alkanes Combustion 0 Be able to write a balanced reaction for the combustion of any hydrocarbon Write the equation for the combustion of 33dimethylhexane CH3 0 CH1 39 C8H18 Halogenation l E w l Hy JE Hi I I HE Fi HE I 39 H H Where X is Cl or Br 0 requires ultraviolet light to initiate the reaction A substitution reaction A reaction in which an atom or group replaces another atom or group in a compound Draw 2chloro4fluorohexane o 2 C8H18 l 2502 gt 16C02 g 18H20g o CH3 CH CH2 CH CH2 CH3 Cl F How many different singly brominated compounds can be prepared from this reaction EHTEHfEHECHFCHE r llJHEa Consider structural isomers only 0 There are only 4 Br 0 CH2 CH2 CH CH2 CH3 CH Br 0 CH3 CH CH CH2 CH3 CH Br 0 CHZ CHZ C CHZ CH3 CH3 0 CH Br How many different singly brominated compounds can be prepared from this reaction 1w EH34H1 EH1 EH EHE I39 Elli EH3 0 There are 5 The terms primary quotsecondaryquot quottertiaryquot and quaternary are defined on page 378 of your text Also note the quotcommon alkyl groups in figure 123 on that page Your Chem 102 instructor may expect you to know these Draw 2heptene o CH3 CHECH CHz CHz CHz CH3 Draw 4methyl2pentyne o CH3 CEC CH CH3 CH3 Alkenes cannot rotate around a double bond This makes cistrans isomers possible in most alkenes See section 133 Draw and label the cis and trans isomers of 2heptene 0 Draw and label the cis and trans isomers of 3methyl2pentene o Chem 101 notes 1252014 Draw and label the cis and trans isomers of 2heptene CH3 CH 2 CH2 CH2 CH3 CC H H cis2heptene H CHQ CHQ CHQ CH3 CC OH H trans2heptene Draw and label the cis and trans isomers of 3methyl2pentene CH3 CH CH3 c c H CH3 C133methyl2peutane H CH2CH3 c c CH3 CH3 Trans Is each alkene cis trans or neither ch xCH3 CH3 lCHgCHgCH3 CC CiC HJ Ha CHa CH CH eithe FH cns H CC CHTr ms CH3 neither CH3 CH2 CHgCHgCH3 CC trans CH3 CIS CHz CH3 Two compounds with the formula C6H12 One is a cyclic alkane the other is an alkene Observe what happens when Brz aq is added to each Which is which o The cycle hexane did not react with Therhexane reacted quickly 0 CH2 E CH CHz CHz CHz CH3Br gt Br Br CH2 CH CH2 CH2 CH2 CH3 0 Addition reactions section 136 HERE a EIE R353 R H1 EVE if o XY can be H2 Clz Brz HCI HBr HOH o Markovnikov s Rule when HX is added the major product will be formed by adding the H the double bonded carbon with the most hydrogen at the start 0 Draw the products of the following reactions o If more than one product is possible draw all products and circle the major product CH 3C ICH3 Pd CH3 quot39 H2 quot CHz CHz CH CHz CH3 CHg CHQ H 5 4 3 2 1 Hgso4 H2C r CH3 CH3 CC HCI a CH H o Mechanism the step by step process by which a reaction takes place The mechanism frequently focuses on the movement of the electrons o The electrons in the second bond of a double bond are more exposed The addition reagent is attracted to the electrons in that bond l r LI H CH3 CHLCH CH2 CH2 CH3 H l CH3 H CH CHz CHg CHQ 35 o This forms a carbocation and a bromide ion 0 The two ions then combine 5 H l CHg gH H CHz CHg Cm gt 6 CH3 CH2 H CHQ CHg CHQ o Markovnikov s rule works because the more highly branched carbocations are more stable 0 least stable primary lt secondarylt tertiary most E C j E Hw E C H E IIzR 0 primary carbocation secondary carbocation tertiary carbocation i1 Chem 101 notes 12102014 Resonance stability The delocalization of the electrons makes the double bonds in aromatic compounds so stable that they will not undergo addition reactions Aromatic compounds are subject to specific substitution reactions a catalyst is always required See section 1310 Draw all possible single substitution products for the following reactions CH3 N02 CH3 CH3 CH3 CH3 Al CH3 H o HNo3 a CH3 N02 sto CH3 CH3 CH3 CH3 H3 CH3 NO2 CH3 N02 TNT N02 HCl 61 H3 CH3 Carboncarbon double bonds are more rigid and much more reactive than carbon carbon single bonds A covalent bond is produced by the overlap of orbitals Dom moo The overlapping orbitals are no longer atomic orbitals they are now molecular orbitals These molecular orbitals are often made from a mixture of atomic orbitals called 39hybrid39 orbitals that are named for the orbitals that contribute to them o hybridization o geometry 0 atomic orbitals used 0 Sp 0 linear 0 one s and one p o 3192 o trigonal planar 0 one s and two p 0 193 0 tetrahedral 0 one s and three p Each type of hybridization produces a set of orbitals a specific geometry Single bonds are formed by the overlap of orbitals in the region between the atoms Such bonds are called sigma 6 bonds Two hybridized carbons and six hydrogen atoms with orbitals forming obonds seven of 3 them To form a double bond you start with a obond but the second bond cannot form directly between the atoms The second bond is formed from unhybridized porbitals that overlap in the areas to either side of the sigma bond Such bonds are called pi 6 bonds unhybnclized p orbitals l l 0 3pquot orbltal 6 bond 1 I Tt bond 3 bond the other 1 of the TE bond A single bond consists of aobond A double bond consists of a obond and a Hbond A triple bond consists of a obond and two nbonds How many sigma and pi bonds are present in the following molecule CH3 I u GHQCEC C CHzC NHz r C There are 32 sigma bonds There areipi bonds
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