General Chemistry I
General Chemistry I CH 221
Central Oregon Community College
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This 8 page Class Notes was uploaded by Maud Bins on Monday October 5, 2015. The Class Notes belongs to CH 221 at Central Oregon Community College taught by Zelda Ziegler in Fall. Since its upload, it has received 12 views. For similar materials see /class/218971/ch-221-central-oregon-community-college in Chemistry at Central Oregon Community College.
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Date Created: 10/05/15
CH 221 7 Ziegler KEY CONCEPTS Chapter 5 Fall 06 10 h Ed Class period1 Readingpp 1667170t170t7170m 170m7171 172m7178 1 Relate the following relative enthalpies of reactants and products sign of AH heat flow between system and surroundings Problem 33 Note There is much in the chapter which we not emphasize particularly PiV work This is why I want you to skim the parts indicated above They give useful background material but you will not be examined on them Class period 2 77 Reading pp 180 7 185 2 Use a thermochemical equation to relate AH to mass of reactant or product andor to AH of the reverse reaction Problems 537 538 3 Relate heat flow to speci c heat mass and temperature change Problems 548 549 551 4 Calculate q for a reaction from calorimeter data Problems 553 554 Class period 3 77 Reading pp 1877195 328b to 331 5 Use Hess law to calculate AH Problems 560 562 Relate AH to enthalpies of formation Problems 561 568 572 a De ne the term bond energy and relate bond energy to bond strength Problems 865 a and b H Skim the pages marked with highlighter for meaning but don t worry about being tested on these topics CH 221 7 Ziegler KEY CONCEPTS Chapter 5 Fall 06 10 h Ed Answers to problems 538 a heat is absorbed b 128 kJ c 0822 g H2 d AH 7907 kj for the reverse reaction and when 270 g CO reacts by this reverse reaction the change in heat is 7875 kj heat is released 548 a A transferred more heat to the water than B did so its capacity to hold heat is greater and its heat capacity is greater b Unless you know how much A and B weighed you can t express its speci c heat capacity which is usually given in units ofJ g C orJgK 554 a 25 kJrnol NH4N03 b endothermic 560 a 90 kj b See energy diagram below 0 562 78677 k 568 a 12 H2 g 12 Brz g 9 HBr g AHf HBrg 73623 kJrnol AHanZ73623 kj b Ag s 12 N2 g 32 02g 9 AgNOg s AHg AgNOg 71244 kJrnol Aern 71244 k c 2Hg C12 g 9 ngclz s AHf Hg2C12 72649 kJrnol Aern 72649 k d 2 C s graph 3H2 12 02 Q9 C2H50H AHfo C2H50H 72777 kJrnol Aern 72777 k CH 221Ziegler NAMING NOTES 1 Compounds containing metals are made up ofions ie are ionic 2 Compounds containing only nonmetals are molecular Exception compounds containing the NHACr ion are ionic Use the pre xes listed in Step 7 unless it is one of the ones that must be memorized step 8 3 The following metals always have the same particular charge when they are ions 1A or 1 metals 1 Al3 AgJr 2A or 2 metals 2 ZnJ 2 3A or 13 metals 3 Cd2 4 Memorize the following polyatomic ions NH4 ammonium CrO42 chromate Hgf 2 mercury I Cr2072 dichromate OH hydroxide 8042 sulfate NOg nitrate 2032 thiosulfate ClOg chlorate CO3 carbonate CzHgoz acetate C2042 oxalate CN cyanide 022 peroxide MnO4 permanganate PO43 phosphate 5 Other oxygenicontaining polyatomic anions can be derived from those in 4 as the following examples show CI0439 Echlorm peri means 1 more O 211 1136 CI0339 chlorm in 4 above e same CIOZ39 chlorite fite means 1 less O than fate ionic Charge CIO hmochlorite hypoi fite means 2 less O than rate CI chloride Those ion naInes listed in italics in 4 above can all be subjected to this system as was the case with chlorate The portion of the name in bold can be applied to the stem of the name of the element Note that not all polyatomic anion naInes ending in ate have 3 oxygen atoms some have 4 oxygen atoms However they follow the naming system as shown above NAMING NOTES Page 2 6 Some polyatomic anions contain hydrogen Their naInes are derived from those in 4 as the following examples show HPO4 2 from HJr and PO43 hydrogen phosphate H2PO4 from two HJr and PO43 dihydrogen phosphate Note that each H4r lowers the negative charge on the anion by one 7 For molecular compounds the following pre xes tell how many of each element is present in the formula Memorize them mono or none 71 hexa 7 6 di 7 2 hepta 7 7 tri 7 3 octa 7 8 tetra 7 4 nona 7 9 penta 7 5 deca 710 8 For each of the following compounds there is only one acceptable naIne called a trivial or common naIne Memorize them H20 water N2H4 hydrazine H202 hydrogen peroxide PH3 phosphine NH3 ammonia AsH3 arsine CH 221 7 Ziegler KEY CONCEPTS Fall 05 Chapter 2 10th ed Class period 1 7 Reading pp 36739t 39m748 1 State what elements and compounds are in terms of atomic theory 2 Relate atomic theory to the Law of Conservation ofmass Problem 28 3 Relate a nuclear symbol to the number ofprotons neutrons and electrons in the atom or ion Problem 223 4 Describe isotopes Problem 220 Class period 2 7 Reading pp 46755 5 State what a molecule is in terms of atomic theory 6 State what an ion is in terms of atomic theory Problems 247 23 7 Classify an element as a metal or nonmetal Problem 22 235 On a quiz or eXaIn you will be asked to classify an element strictly as a metal or nonmeml 8 Relate structural condensed structural and molecular formulas Problems 245 241 9 Predict formulas ofionic compounds Problem 253 251 249 Class periods 3 and 4 7 Reading pp 60767 10 Given the formula of any of the following classes of compounds name the class to which the compound belongs and write the name Given a name write the formula Classes ionic binary molecular acid Problems 24 255 259 261 263 265 NOTE The only element naInes and symbols you will need to know are those from Chapter 1 You also will need to have memorized the information in the Naming Notes handout which can also be found on web site httpq gwwwcoccedugzzieglerg click on CH 221 then Handouts then Naming Notes Page numbers in Shaded type are pages that should be read for main points only Read the captions pay attention to bold teXt and know what is going on The usual science7 type reading is not necessary here For the Monday Thursday Lecture Section Class Period 1 Key Concepts 1 2 3 4 5 Class Period 2 Key Concepts 6 7 8 9 Class Period 3 amp half of 4 Key Concept 10 CH 221 7 Ziegler KEY CONCEPTS Fall 05 Chapter 2 10th ed Chapter 2 Answers to assigned problems See Text page A2 for answers to red questions 28 a 6116 g Sulfur b Conservation of Mass c According to postulate 3 of the atomic theory atoms are neither created nor destroyed during a chemical reaction lf0384 g of Hydrogen are recovered from a compound that conmins only H and S the remaining mass must be Sulfur 220 Since the two nuclides are atoms of the same element by de nition they have the same number of protons 54 They differ in mass number and mass because they have different numbers of neutrons 129Ke has 75 neutrons and 130Xe has 76 neutrons 24 In a solid particles are close together and their relative positions are fixed In a liquid particles are close but moving relative to each other In a gas particles are far apart and moving All lonic compounds are solids because of the strong forces among charged particles Molecular compounds can eXist in any state solid liquid or gas CH 221 7 Ziegler KEY CONCEPTS Fall 05 Chapter 1 10th ed Class period 1 7 Reading pp 1712 1 From its composition identify a sample ofmatter as an element compound or mixture Problem 115 2 For any element in Table 12 given the element name write the atomic symbol or vice versa Problems 111 113 3 Classify a mixture as a solution or heterogeneous Problem 11 19 4 Determine whether a property of matter is a physical or chemical property Problem 12 120 Class period 2 7 Reading pp 14717 20725 5 State the appropriate Slmetric unit for a given quantity Or given a unit smte the quantity being speci ed Problem 13 163 6 Convert between OF 0C and K Problem 133 7 Distinguish between precision and accuracy for measured numbers Problems 14 161 8 Determine the number of signi cant gures in a measured quantity Problems 15 137 139 9 Determine the number of signi cant gures in a calculated quantity Problem 141 142 Class period 3 7 Reading pp 25m 7 28 10 Use conversion factors to change the units ofa measured quantity Problems 145 147 149 11 Relate density to mass and volume Problems 131 156 166 169 a b NOTE Class periods above are for the MWF lecture sections If you are in the MR lecture the class periods break down as below Adjust your reading accordingly Class Period Key Concepts 1 2 8711 CH 221 7 Ziegler KEY CONCEPTS Fall 05 Chapter 1 10th ed Answers to assigned problems For all problems in the book whose numbers appear in Red Ink please see Appendix A ofyour text which starts on page A71 12 Chemical change 120 a chemical bphysical c physical d physical the production of soot is a chemical change but the deposition of soot is a physical change 13 a time b density c length d area e temperature f volume g temperature 14 Measurements darts that are close to each other arepreme Measurements that are close to the true value are ammzte a Figure ii both accurate and precise b Figure l precise but not accurate c Figure iii imprecise but their average value or geometric center point is close to the bull s eye so their average is very accurate 161 a Student I ave 2251 Student 11 ave 2261 Student I is more accurate b average deviations student I 002 student H 002 the two sets show the same precision even though set I is more accurate 142 723 X 102 156 470 ft 166 There are lots ofways to do this Here s one way Select a common unit for comparison say the cm Then recall that 1 in N 25 cm 1 m 100 cm Also it is helpful to notice that 57 cm is close to 50 cm which is about half as big as the 11 m length 14 in is about 15 times 10 inches which is easier to convert to cm 25 cm so 14 in is around 25 12 cm Sometimes you have to do the conversions like when the estimation method isn t good enough and sometimes you don t as was the case here It is useful to make these ballipark estimates so that you can judge whether your answer is right when you do go through with the more formal conversions 169 a 467 gcm3 b 254 L ofmercury
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