General chemistry 210 chapter 4 notes
General chemistry 210 chapter 4 notes chemistry 210
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This 23 page Class Notes was uploaded by danayit desalegn on Sunday October 4, 2015. The Class Notes belongs to chemistry 210 at St. Cloud State University taught by Dr. Tom Gardner in Fall 2015. Since its upload, it has received 26 views. For similar materials see general chemistry 210 in Chemistry at St. Cloud State University.
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Date Created: 10/04/15
Chapter 4 Reactions in Aqueous Solutions Copyright 2012 The McGrawHill Compaies Inc Permission required for reproduction or display 242015 A Types of Chemical Reactions Four generic types of reactions 1 Combination 3 Single Replacement AB c AxB ABx c 02 9 co2 Cuso4 Zn 9 Znso4 Cu 2 Decomposition 4 Double Replacement metathesis swa in A gt B c pp 3 AXBY9AYBX 2Hg092HgO2 AgNO3 NaCI 9 AgCI NaNO3 El 2 A Drlvmg Forces For reactions in solution involving ions there are three driving forces Formation of a Precipitate Gas Weak electrolyte E1 242015 General Properties of Aqueous Solutions Electrolytes and Nonelectrolytes A solution is a homogeneous mixture of two or more substances Solutions may be gaseous such as air solid such as brass or liquid such as saltwater Usually the substance present in the largest amount is referred to as the solvent and any substance present in a smaller amount is called the solute Throughout the remainder of this chapter unless otherwise noted solution will refer specifically to an aqueous solution El 4 General Properties of Aqueous Solutions Electrolytes and Nonelectrolytes An electrolyte is a substance that dissolves in water to yield a solution that conducts electricity By contrast a nonelectrolyte is a substance that dissolves in water to yield a solution that does not conduct electricity The difference between an aqueous solution that conducts electricity and one that does not is the presence or absence of ions I Nut lil Nil Wing Cl flitI d if U1 r General Properties of Aqueous Solutions Electrolytes and Nonelectrolytes Dissociation is the process by which an ionic compound upon dissolution breaks apart into its constituent ions Ionization is the process by which a molecular compound forms ions when it dissolves Hillter retrain if mm 242015 41 J General Properties of Aqueous Solutions Electrolytes and Nonelectrolytes Acids constitute one of two important classes of molecular compounds that are electrolytes Molecular bases constitute the other one A base is a compound that dissolves in water to produce hydroxide ions OH Militia HJUEF lling 39 39l iflu t ll El 7 41 J General Properties of Aqueous Solutions Strong Electrolytes and Weak Electrolytes An electrolyte that dissociates completely is known as a strong electrolyte All watersoluble ionic compounds dissociate completely upon dissolving so all watersoluble ionic compounds are strong electrolytes iii a 41 General Properties of Aqueous Solutions Strong Electrolytes and Weak Electrolytes The list of molecular compounds that are strong electrolytes is fairly short The Strong eld39s T lELE 431 Acid ll nlii l n Equation layulrrnciil ai39ivc acid l li lrml i l gtrrrjfl l CI Lllrrrgrl 39339Lifithlt1l l LillL39iill lll nlnrrqlrl II39Ilivrq39l rlr liftsan E39EEFilIiijlll39 39i39li H mji i II irrrlri lunar Nitric Lttltll I l z m H iu39rlrl 339 IEJEJI ZI E llltlrril Iuid H FI HIHJHJI l H 39 lal39rlti Fl Eirrr hT 39ltllnril email lil fil39 jlgmju 1 I I39i mlrl 39ljl3939 iiirri Hhhlli39lli39ili mid lllri i39 ial i iiil I 1 IIquot Hm 50 I xrrrg39l IISihlu qgl Illnlmjl Htii39mqi i e 242015 41 General Properties of Aqueous Solutions Strong Electrolytes and Weak Electrolytes Most of the molecular compounds that are electrolytes are weak electrolytes A weak electrolyte is a compound that produces ions upon dissolving but exists in solution predominantly as molecules that are not ionized Most acids except those listed in Table 41 are weak electrolytes Hc zirilogli mm 231430 5 my 10 41 General Properties of Aqueous Solutions Strong Electrolytes and Weak Electrolytes Note that the ammonia molecule does not ionize by breaking apart into ions Rather it does so by ionizing a water molecule e E o l I l l39 1 ll lil HI twirl K m Blurle 11 41 General Properties of Aqueous Solutions Strong Electrolytes and Weak Electrolytes 12 I r Strong Electrolytes Weak Electrolytes L and Noneilectrolyles n eleclrolyie is a substance th at wherrljussollved In waiter results ii a solulion that can cn nducl electricin The Ilghil bulb will light if a substance is an electrole a t rw nt m ramw cmn amp 242015 I General Properties of Aqueous Solutions Identifying Electrolytes A good first step in identifying electrolytes is to determine whether the compound is ionic or molecular An ionic compound contains a cation which is either a metal ion or the ammonium ion and an anion which may be atomic or polyatomic A binary compound that contains a metal and a nonmetal is almost always ionic Any ionic compound that dissolves in water is a strong electrolyte El 14 I 41 General Properties of Aqueous Solutions Identifying Electrolytes If a compound does not contain a metal cation or the ammonium cation it is molecular In this case you will need to determine whether or not the compound is an acid Acids generally can be recognized by the way their formulas are written with the ionizable hydrogens written first 401 General Properties of Aqueous Solutions Identifying Electrolytes I Its like mmmnd or uhmln ll Ilia r Hull ELIE TIE Il39liIITII HLillil I ii arr1m ellwimlg39m 1115 a 71 1 777 39 F I h ill 1 mad n Flume ur limiter i 11 ll 533quot Krill IIHJE bxHr V 39quotL V r ain t 74 r i quot In H E 1 III39H aluminium l jl i agZ i39IIJIE39IHLII III ii L xiiiquotng victimlyre nInnt39ltic39imlyic 39Z n 139 i Ji I I I mm Milli aimla senum um Bali13931 mTulil all 39 i a 17 7 r g 1 Inn E in g 5 7 E 7 W TI I E nilFHIIJI39NI in i39itrnpnumil 31 altrliilig39relzclm g Int39 1 Etllr c ln lnt lyln i 16 242015 402 Precipitation Reactions Solubility Guidelines for Ionic Compounds in Water An insoluble solid product that separates from a solution is called a precipitate A chemical reaction in which a precipitate forms is called a precipitation reaction i 18 402 Precipitation Reactions Solubility Guidelines for Ionic Compounds in Water 19 i 242015 Precipitation Reactions Solubility Guidelines for Ionic Compounds in Water When an ionic substance such as sodium chloride dissolves in water the water molecules remove individual ions from the threedimensional solid structure and surround them This process called hydration 20 Eli 2 Precipitation Reactions Solubility Guidelines for Ionic Compounds in Water Solubility is defined as the maximum amount of solute that will dissolve in a given quantity of solvent at a specific temperature Not all ionic compounds dissolve in water 22 4102 Precipitation Reactions Solubility Guidelines for Ionic Compounds in Water I in ElILlE 41 E lubill w Guidelines lut lE Enmpwndfa Wa wa uiuhl e ummud ll lwlllhliEiEEilFtM ll Flirlqhmmlil minimlulllg1 n11 alllgtlll lumml mum Ilaquot Nnll391l139 39 lumpminds titjamming uliu minim Emil IllEU l tlL39ilt LuIlL39 Illilll l If all fl If cl lllu ntli hm lfl II 5 V I or lch unrimttirliuuzu mrl l hl ll I Fiilumrhmmli unnlmining Elfin ElllillriilLquot in tilli llrvlil39l lrlllill ell mil llga mijg Ag hnHI39Lillu lurl l Hill quot I mr lulllillll lL irL vl lulu Hr Pl39Iquotquot llEerHIHLIHv containing ll39iu suljl alu lam SITE Ll fhllll39l ill39ILHIFlljh minluiunjrng Ag 1 I llgj Fla 39 fall l Er quot liar FliEi 39 412 Precipitation Reactions Solubility Guidelines for Ionic Compounds in Water Till lEl LE All 3 Solubility Guidelines In E llu hie Compou ri e WallerInsoluble E mpoundi Soluble EmeIarns fliunlmmntla c nljjillriilng tilquot Eilrl nnmlu lulu IF I plasmrlkmli meg numls unnuinilrtB Li iiunlWilll l1riil11llu lun lf39r jm CI utr hLllllil L39 imu l lnl Na K I Fl l39Il39 EC inquot NH Iiquot39ii111nuunill minluinujg ll39n hyalnwiili mull it39llVii fitimmmmila gliljllalllmllng Ll Hillr Rl lilrl tryLi HI Ha 402 Precipitation Reactions Molecular Equations Phll l gljiriq ENHIIIHIH t El slt lN Uilrrql Phlj l This equation as written is called a molecular equation which is a chemical equation written with all compounds represented by their chemical formulas making it look as though they exist in solution as molecules or formula units Precipitation Reactions Ionic Equations ENHHIWJ SH I mg l Bar i 12qu 39r ZHHI 3th t 3 35 al1 Et39I39E l 39r 3 1H L I FIJI H 2155 39339 LI 339 I This version ofthe equation is called an ionic equation a chemical equation in which any compound that exists completely or predominantly as ions in solution is represented as those ions 1 1 27 i E 242015 Precipitation Reactions Net Ionic Equations Ions that appear on both sides of the equation arrow are called spectator ions because they do not participate in the reaction Hleifrll E Silliiulriql Bturklitiq 39 EPILISiti39i yi l anHI Qt39glliim I is thiii Buyitmi Sl lrwl r B39 39l ijriln lll This version of the equation is called a net ionic equation which is a chemical equation that includes only the species that are actually involved in the reaction 28 Precipitation Reactions Net Ionic Equations The steps necessary to determine the molecular ionic and net ionic equations for a precipitation reaction are as follows 1 Write and balance the molecular equation predicting the products by assuming that the cations trade anions 2 Write the ionic equation by separating strong electrolytes into their constituent ions 3 Write the net ionic equation by identifying and canceling spectator ions on both sides of the equation 29 Acid Base Reactions Strong Acids and Bases Strong Acids and Stron g Bases Strung Acids Etmngl Bans Hfl LiU IH I mgquot HHUIEI H l K llil lEl H39lfjrr l3 hf 1H l llfllizh Fh l l iIIlE39l 1 Call It I H j EliESE Erll k ll Egul H I 31 242015 Acid Base Reactions Arrhenius Theory of Acids and Bases Svante August Arrhenius 18591927 r Based on his studies of solution f 39 conductivity Arrhenius developed the mm r concept of tons and his 1887 theory 1 of acids and bases is based on ions Acid is H donor quotprotonquot h Base Alkali is OHquot donor Arrhenius also did fundamental work on chemical kinetics and was the first to study what we now call the Greenhouse Effect 32 Acid Base Reactions Br nstedLowry Acids and Bases Johannes Nicolaus Br nsted Copenhagen 18591927 and Thomas Martin Lowry England 18591927 l f i f l In 1923 independently proposed new theory to explain basicity of compounds without hydroxide Acid is H donor Base is H acceptor I T M Lowry Chem Ind Land l 39 1923 42 43 l 33 10 AcidBase Reactions Br nstedLowry Acids and Bases ll ll hill I39 Hl39l39f l lj ijl ii M l i mjri ll l39i gi qi 39 l39 quot 4 HFlrlifl 39li39g iii E H inn aw F39mqi ir l nm him Emr 34 242015 a o H 0i AcidBase Reactions Br nstedLowry Acids and Bases The BronstedLowry definitions of acids and bases are not restricted to species in aqueous solution I Itr iigi N Hgigi NHJEHLil 35 AcidBase Reactions Br nstedLowry Acids and Bases Most of the strong acids are monoprotic acids meaning that each acid molecule has one proton to donate Acids such as HZSO4 are diprotic acids meaning that each acid molecule has two protons that it can donate There are also triprotic acids those with three protons such as phosphoric acid H3PO4 In general acids with more than one proton are called polyprotic acids 36 11 AcidBase Reactions Br nstedLowry Acids and Bases HZSO4 is strong only in its first ionization in water l39flg t JJimqi H quot39 l my llSUI ism llSD mli HWuq l S ll39le qu For all other polyprotic acids each ionization is incomplete l lalr llgl iiql il39l b iuql I ligPU39jiuql H firquotmam 1 Hm J Hriri fmm Hedi mm Ht qu Fiji um l liP gl 3 l 5 ngFDII 3v lllle 39l a FUSE l 37 242015 AcidBase Reactions AcidBase Neutralization base In general an aqueous acid base reaction produces cation from a base and the anion from an acid Ht fliirm Nui Hiuql Hg iii Naililljiriil H quot l uni 1 Cl J nigh Na quotquot l rim UH tiff a H can DH my H 3C1 ll 38 A neutralization reaction is a reaction between an acid and a water and a salt which is an ionic compound made up of the HgUlll v NilPlil39rjll S 391qu OxidationReduction Reactions Oxidation Numbers An oxidationreduction reaction or redox reaction is a chemical reaction in which electrons are transferred from one reactant to another Emu CLIIHHHM Emblem quott Cuts In this process zinc atoms are oxidized they lose electrons and copper ions are reduced they gain electrons 39 12 OxidationReduction Reactions Oxidation Numbers Redox halfreactions E39an Elljmlti l 2rquot Surfing 2quot CLll Jn Zillrlx Culinary 2nrquot En 111qu Cum 2rfquot Oxidation is the loss of electrons and the gain of electrons is called reduction Zn is called the reducing agent because it donates electrons causing Cu2 to be reduced Cu2 is called the oxidizing agent because it accepts electrons causing Zn to be oxidized 4o 242015 OxidationReduction Reactions Oxidation Numbers H SEE7 3 l Him 2 il liTFl 1 l Fluorine does not gain an electron per se and hydrogen does not lose one Experimental evidence shows however that there is a partial transfer of electrons from H to F Oxidation numbers provide us with a way to quotbalance the books with regard to electrons in a chemical equation The oxidation number also called the oxidation state is the charge an atom would have ifelectrons were transferred completely 41 OxidationReduction Reactions Oxidation Numbers Hgi Fjigl 2 Him l t2 ll u I NEW Sliglgl 65 ENlE ligiyi ll ii 39339 l The elements that show an increase in oxidation number hydrogen in the preceding examples are oxidized whereas the elements that show a decrease in oxidation number fluorine and nitrogen are reduced 42 13 Oxidation Reduction Reactions Oxidation Numbers Because compounds are electrically neutral the oxidatio numbers in any compound will sum to zero is equal to its charge n For a polyatomic ion oxidation numbers must sum to the charge on the ion The oxidation number of a monatomic ion 43 242015 Oxidation Reduction Reactions Oxidation Numbers The following guidelines will help you assign oxidation numbers There are essentially two rules 1 The oxidation number of any element in its elemental form is zero charge on any polyatomic ion The oxidation number 0 monatomic ion is equal to the charge on the ion 2 The oxidation numbers in any chemical species must sum to the overall charge on the species Oxidation numbers must sum to zero for any molecule and must sum to the fa 44 Oxidation Reduction Reactions Oxidation Numbers mls i n Elmquot Human Enigma NEEaim r I liJi39ILrp Mair Hil 1 25 lFLELiEl Myriam IIE Ill IlrriEr ii ri hilli1iilTIliLllIIIiiunililiiilrc l I39 rr h maul bulimia irui Flyilnaitu ILtallil lfaw hill um All ith ITIEliLJIMMI mandala H lJ A in hull L39Imtplw It gtquot a I FLIIF L iIIIIHS IiI39IJIIIIII 391al l Mlllllclzlllllgllljgliici run II39 II39I lm FINEHINT Ll lEL39Idllj ll dillurnquot tiinEJiiim annuluu39li 39 rule I m Jazminquot titl IILalll ra39illlhitlil imlllp 539ij dllsi RISE thei39l39iiiililf39liquotElih39r39il H rI39ilu39l1l39l39 Illuli ni KIT Ii j i In ll l E nil in Herman with Reliable l39d ll Numbers in Emma our My ml Ema 45 14 Oxidation Reduction Reactions Oxidation of Metals in Aqueous Solutions Em 1 C Uflgl my 39 EIIC l 3 real Eula l u 1 39 n I 1 1 v I J I This is an example of a displacement reaction Zinc displaces or replaces copper in the dissolved salt by being oxidized from Zn to Zn Copper is displaced from the salt and removed from solution by being reduced from Cu2 to Cu Chloride CI which is neither oxidized nor reduced is a spectator ion in this reaction 47 242015 it4 Oxidation Reduction Reactions Oxidation of Metals in Aqueous Solutions CHI 1 Eliflgl aqi no reaction No reaction occurs between Cus and Zn2aq whereas a reaction does occur between Zns and Cu2aq because zinc is more easily oxidized than copper 48 Oxidation Reduction Reactions Oxidation of Metals in Aqueous Solutions FEARLE LG MEEWHIIH Equot L 39 heme mg r L L39 I i Ill VIIIquot E I Ml in I E1 39 quot 49 15 OxidationReduction Reactions Oxidation of Metals in Aqueous Solutions Metals listed at the top of the activity series are called the active metals Metals at the bottom of the series such as copper silver platinum and gold are called the noble metals because they have very little tendency to react Reactions in which hydrogen ion is reduced to hydrogen gas are known as hydrogen displacement reactions 50 242015 OxidationReduction Reactions Balancing Simple Redox Equations 39rlxl Ni2 litrer Irl 39rmal Nita Cris l Ell l ltlf i Firquot N39iiflmji 214 Nils 2quotlcslllw39ll39 quot C l ljltliff gquot l 3Nl3391lrrql Him 51 OxidationReduction Reactions Balancing Simple Redox Equations Ifll l 2111 law the 21115 l RNl39uluql 3CIquot lIitiql 3MB This method is known as the halfreaction method of balancing redox equations 52 16 OxidationReduction Reactions Other Types of Redox Reactions Combination Reactions from its constituent elements can involve oxidation and reduction NEHH Myl39 l ix iMl llgl i 1 ii i Tu Tu 39 39 39 quotT Combination reactions such as the formation of ammonia 55 242015 OxidationReduction Reactions Other Types of Redox Reactions Decomposition the following examples ZNHHM 2Nui rl l Hljlgl E El U E i 1 Ti Eli if j 139 i EKEIU l Uglyl all 5517 1Lvl iquot 17 l 39 I I ll 1 if 7 Decomposition can also be a redox reaction as illustrated by 56 OxidationReduction Reactions Other Types of Redox Reactions The decomposition of hydrogen peroxide is an example of a disproportionation reaction in which one element undergoes both oxidation and reduction L39lklllljillillllll39l f WdUL39l mm Eligijjcmyi EHEDHJ film I l I 2 if a 2 n 57 17 OxidationReduction Reactions Other Types of Redox Reactions Combustion is a redox process CH4va 202w E jlgrl Erwin 4r ll i4 Vquot J i l a Lg EJ ml 4 I H mt 1 1 58 i d 242015 OxidationReduction Reactions A A 77 it Concentration of Solutions Molarity One of the factors that can influence reactions in aqueous solution is concentration The concentration of a solution is the amount of solute dissolved in a given quantity of solvent or solution 18 242015 405 1 Concentration of Solutions illlnrru ltczilril M Ill il llii l39lll liilli u ll39ill ll m Minna mill paialiclm w a Hillnan Emu er 39HquotllIr39 pa39IrluIIE39r min um milling 80 405 1 Concentration of Solutions Molarity Molarity or molar concentration symbolized M is defined as the number of moles of solute per liter of solution mmle mimics mime Ellen Milllll n 62 405 1 Concentration of Solutions Dilution Dilution is the process of preparing a less concentrated solution from a more concentrated one moles ifsolute helprc tli lutrion moles of solute lifter dilution gt i lll lc i l lj llllc mule Ul Mill lllJlllS K Ilium Hr Hnlluljtm Ilium HF mu liun L1 Mga X LEE M X mlLL E Mu K lllLd millimoles mmOI 64 19 242015 45 Concentration of Solutions Serial Dilution 39l V Ii n l I I y I Q The MCG erlll Comp rules Inchharles Winters p alagrapher 391 a 66 45 Concentration of Solutions Solution Stoichiometry Nt lESELl Hi ENtlrrrJrI S iulfnql Therefore a solution that is 035 M in NaZSO4 is actually 070 M in Na and 035 M in 5042 Square brackets around a chemical species can be read as quotthe concentration of that species For example Na is read as quotthe concentration of sodium ion i 68 46 Aqueous Reactions and Chemical Analysis Gravimetric Analysis Gravimetric analysis is an analytical technique based on the measurement of mass i 70 20 Aqueous Reactions and Chemical Analysis AcidBase Titrations In titration a solution of accurately known concentration called a standard solution is added gradually to another solution of unknown concentration until the chemical reaction between the two solutions is complete If we know the volumes of the standard and unknown solutions used in the titration along with the concentration of the standard solution we can calculate the concentration of the unknown solution 72 242015 Aqueous Reactions and Chemical Analysis AcidBase Titrations A solution of the strong base sodium hydroxide can be used as the standard solution in a titration but it must first be standardized because sodium hydroxide in solution reacts with carbon dioxide in the air making its concentration unstable over time We can standardize the sodium hydroxide solution by titrating it against an acid solution of accurately known concentration 73 Aqueous Reactions and Chemical Analysis AcidBase Titrations potassium hydrogen phthalate KHP aillifxlliyEJ trlifl r NLli lIIiilqi e KMLCal l 39lmi e fl Hj lii HEITHJQMUKH 74 21 242015 46 Aqueous Reactions and Chemical Analysis AcidBase Titrations HC3H4DEUWJ Dilll um CHZl Di l riq l lj l i ll ll Aqueous Reactions and Chemical Analysis I 46 Aqueous Reactions and Chemical Analysis AcidBase Titrations The point in the titration where the acid has been completely neutralized is called the equivalence point It is usually signaled by the endpoint where an indicator causes a sharp change in the color of the solution In acid base titrations indicators are substances that have distinctly different colors in acidic and basic media 22 Aqueous Reactions and Chemical Analysis Redox Titration Another quantitativeanalysis method is redox titration Redox titration involves the use of an oxidationreduction reaction with one reactant being delivered via a burette In one common type of redox titration the titrant is a solution of potassium permanganate which serves both as the oxidizing agent and the indicator 81 242015 Aqueous Reactions and Chemical Analysis Redox Titration EMINUJIHIH fixCg i rim l 1511 Elixir Ellilinl lilriqj ffJ3fIf Jr l iuql EWDdnq l i Mrquot I h39 I Naggingq i A A E 82 it 23
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