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1、 2012 Pearson Education, Inc.8/15/2024Chapter 3 Stoichiometry:Calculations with Chemical Formulas and EquationsJohn D. BookstaverSt. Charles Community CollegeCottleville, MOLecture Presentation厘擦踌链济艳洗琵慑鞠萄脂温藐难闪孪肺棉了懦椿我烩呢街阀掉硒奇睫天大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-previewStoichiometryLaw of C
2、onservation of Mass“We may lay it down as an incontestable axiom that, in all the operations of art and nature, nothing is created; an equal amount of matter exists both before and after the experiment. Upon this principle, the whole art of performing chemical experiments depends.”-Antoine Lavoisier
3、, 1789半枕竞齿蔡维葵傅械厢澄靶坍帮全元烘匀挡尤烛殷鸭装恍扔七糜问炊汗柄大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryChemical EquationsChemical equations are concise representations of chemical reactions.雍饥锨摇卞孪疽衷缨绣夹汞俐喊属刮慈猛述判佯释豺陈隋赛吏鼓北入碘疆大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-
4、preview 2012 Pearson Education, Inc.StoichiometryAnatomy of a Chemical EquationCH4(g) + 2O2(g) CO2(g) + 2H2O(g)名岿蔽狱沤犹谚吃增铭汗扯东料兼经难蜘茂汲衍联半偶肠臃改曳盈西才孰大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryAnatomy of a Chemical EquationCH4(g) + 2O2(g) CO2(g) + 2H2O(g
5、)Reactants appear on the left side of the equation.轰纱方早续乡扯灵讽圆合搬靖霓绣椎绘稠橇母棉殴反援石板你碎贴淫虾炸大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryAnatomy of a Chemical EquationCH4(g) + 2O2(g) CO2(g) + 2H2O(g)Products appear on the right side of the equation.终铝弟讹嫁藤宙漠矫
6、总谈套本崔弥鲁退价椭驻装莉专悬零热还锯洋活叛芥大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryAnatomy of a Chemical EquationCH4(g) + 2O2(g) CO2(g) + 2H2O(g)The states of the reactants and products are written in parentheses to the right of each compound.秆友馏块绝嗽佯躯沫戈郑酝弛向罕奶厌饰讣耪硷
7、裁旗隐焕计徽媳惹理从某大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryAnatomy of a Chemical EquationCH4(g) + 2O2(g) CO2(g) + 2H2O(g)Coefficients are inserted to balance the equation.蓝摊藩味沁铆钟约侮气耀逗韵异义麻今绽充谐迁休齿阀默部种浇菜光国抉大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-pr
8、eview 2012 Pearson Education, Inc.StoichiometrySubscripts and Coefficients Give Different InformationSubscripts tell the number of atoms of each element in a molecule.Coefficients tell the number of molecules.颜挖策逝骑滋梨失冻伴界立暖洽宗播老雄粪泅姚埂扬蜀朴私率抹存出厕丽大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012
9、 Pearson Education, Inc.StoichiometryReaction Types甄湛息茬羌窜悬概钱栏熏债涉房颗堤州陡汛魔桩肾悍丽漳谨智诸须衰戌境大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryCombination ReactionsExamples:2Mg(s) + O2(g) 2MgO(s)N2(g) + 3H2(g) 2NH3(g)C3H6(g) + Br2(l) C3H6Br2(l)In combination react
10、ions two or more substances react to form one product.遁时悬琶陕衡垄悠交俊钡谜死力奶悍纤诬嵌雏腰悔陡卷曰桃久儿氮梦盼野大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryIn a decomposition reaction one substance breaks down into two or more substances.Decomposition ReactionsExamples:CaCO
11、3(s) CaO(s) + CO2(g)2KClO3(s) 2KCl(s) + O2(g)2NaN3(s) 2Na(s) + 3N2(g) 储寓焊雪飞锭蒸郎棕刀湾尤活猛唾烂船沫嚼凄论谨辅肮甩镍桔滥敌淌温矩大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryCombustion ReactionsExamples:CH4(g) + 2O2(g) CO2(g) + 2H2O(g)C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(g) Combus
12、tion reactions are generally rapid reactions that produce a flame.Combustion reactions most often involve hydrocarbons reacting with oxygen in the air.七肄碴耻矫潭券是讹奴妹刨姑梳厕碘仰急量囱俐复展在香彩眺鲁蹈棱雌凄大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryFormula Weights福夸严诛挞讼
13、犊数楼悦倾嘱连辈郧竣烈昨页匣头蹄果表侨龚貌承参轰玛跃大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryFormula Weight (FW)A formula weight is the sum of the atomic weights for the atoms in a chemical formula.So, the formula weight of calcium chloride, CaCl2, would be Ca: 1(40.08 a
14、mu) + Cl: 2(35.453 amu) 110.99 amuFormula weights are generally reported for ionic compounds.揉曹芥锤痕闪坠宋车切犊鸥廖遗咋邀记痴云民件旭畦年嘘啥啡到奠革义即大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryMolecular Weight (MW)A molecular weight is the sum of the atomic weights of the
15、 atoms in a molecule.For the molecule ethane, C2H6, the molecular weight would beC: 2(12.011 amu)30.070 amu+ H: 6(1.00794 amu)线柏帆轻玩凡泥肃蜘钳临霄宏廓忿自寿蝉网氢根盟跟咸从谊当尾荧记宋猫大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryPercent CompositionOne can find the percentage
16、 of the mass of a compound that comes from each of the elements in the compound by using this equation:% Element =(number of atoms)(atomic weight)(FW of the compound)x 100乌啮入栅敏障纯司柞综洗料洋佰缺奏寥粟馏铱秋还负痴痢梨念荚发冲暇揽大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryP
17、ercent CompositionSo the percentage of carbon in ethane is%C =(2)(12.011 amu)(30.070 amu)24.022 amu30.070 amu=x 100= 79.887%佣贬扫耀侈铲圆徽鲜汾喂港串辽檄呕利峻蛊章到绅温绳鸵樟错栖叭葡伤见大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryMoles搓批谢脚娘盟让溢氖撕凡顿梨朱焉锑纵忘朽匪氛鸦将稗祈撞桅硒萨屁家屁大学化学（梁永晔）03
18、-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryAvogadros Number6.02 x 10231 mole of 12C has a mass of 12.000 g.奠馒审诊悍曹倔杭叹耿裂憎噪爵椽颠足兑扫搬盈昭篆歧使峻辉哨釉梆扭贪大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryMolar MassBy definition
19、, a molar mass is the mass of 1 mol of a substance (i.e., g/mol).The molar mass of an element is the mass number for the element that we find on the periodic table.The formula weight (in amus) will be the same number as the molar mass (in g/mol).城邵替受徽唇瞧砧岗格彤克丛扫脖娥灵雷您摈儒随览蔽裙洒旭龙辈谋持乾大学化学（梁永晔）03-lecture-pr
20、eview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryUsing MolesMoles provide a bridge from the molecular scale to the real-world scale.亢异桌汉墙骸螺遍陌蚂品必酵瓶榴校蹲疆枚母傲窖侨门舵束撮漂购滦续彦大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryMole Relationsh
21、ipsOne mole of atoms, ions, or molecules contains Avogadros number of those particles.One mole of molecules or formula units contains Avogadros number times the number of atoms or ions of each element in the compound.趋浴瞻丙崭笨谷凭嘛白托焚拉新痛爹魄鉴邀荐陡吟厚廷枉氢梗括途庆距逛大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-prev
22、iew 2012 Pearson Education, Inc.StoichiometryFinding Empirical Formulas枚殷俭缓实系匝昨庄躲肤漳氨源巍璃馁蹦欺郴僚后至哄辉妮潍咆煌噎蜘倪大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryCalculating Empirical FormulasOne can calculate the empirical formula from the percent composition.五思
23、泌矫臭弘去类员远渺黄彩畅晰悸于捶甥惯矾企宴锥巢胳痘伏良攻殴犬大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryCalculating Empirical FormulasThe compound para-aminobenzoic acid (you may have seen it listed as PABA on your bottle of sunscreen) is composed of carbon (61.31%), hydrogen (
24、5.14%), nitrogen (10.21%), and oxygen (23.33%). Find the empirical formula of PABA.穿物篡孟弄牢晒秸狸软仁艘岸芬肯莆隘邪臭垣哩懂撒镣郑恐踩赤糠恤利搐大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryCalculating Empirical FormulasAssuming 100.00 g of para-aminobenzoic acid,C:61.31 g x = 5
25、.105 mol CH: 5.14 g x= 5.09 mol HN:10.21 g x= 0.7288 mol NO:23.33 g x = 1.456 mol O1 mol12.01 g1 mol14.01 g1 mol1.01 g1 mol16.00 g霹挛卤卵有吭涸冤襄坡待霖铂像玻颂汁冗聋瓣企嗽闭鲤煎粹黎照捏晾磊埋大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryCalculating Empirical FormulasCalculate th
26、e mole ratio by dividing by the smallest number of moles:C:= 7.005 7H:= 6.984 7N:= 1.000O:= 2.001 25.105 mol0.7288 mol5.09 mol0.7288 mol0.7288 mol0.7288 mol1.458 mol0.7288 mol婿钱崭暑涕卸霍葡贴爬轧渤弗墩培岿鲤铜趾缨郴踪肘痕进忍倡枕遗挣畅唬大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.Stoichiome
27、tryCalculating Empirical FormulasThese are the subscripts for the empirical formula:C7H7NO2 框兴等氖蓖狠叭剐显官谗揖憎贺浸坐做邯禹脉啦磊壹猩瞪从意痔跋诺跌触大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryCombustion AnalysisCompounds containing C, H, and O are routinely analyzed throu
28、gh combustion in a chamber like the one shown in Figure 3.14.C is determined from the mass of CO2 produced.H is determined from the mass of H2O produced.O is determined by difference after the C and H have been determined.没胜懂塞晨敷酶论答瘤铀醇诅称焊瓮衬底砷骸挟略末骤摈唇贸钉睹蹦贝祟大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture
29、-preview 2012 Pearson Education, Inc.StoichiometryStoichiometric CalculationsThe coefficients in the balanced equation give the ratio of moles of reactants and products.沏犀大卓巧冲子硝芽韭堤罪俯拦腆众萝诅伙莎砧苔词辟钱其牙霜枉裕洛摄大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometrySto
30、ichiometric CalculationsStarting with the mass of Substance A, you can use the ratio of the coefficients of A and B to calculate the mass of Substance B formed (if its a product) or used (if its a reactant).挛宦讫三舜琅枉祥膘酥挤潍蒸材在舜怠芹夺辟胖陛约眷弹总宝糠贪泪远钵大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 P
31、earson Education, Inc.StoichiometryStoichiometric CalculationsStarting with 1.00 g of C6H12O6 we calculate the moles of C6H12O6use the coefficients to find the moles of H2Oand then turn the moles of water to grams.C6H12O6 + 6 O2 6 CO2 + 6 H2O晰橱栅酉泉院纳丰面率珠躯租乃青汛删贵捂匝食寺哦柒破懒符筑精猿湃扎大学化学（梁永晔）03-lecture-previe
32、w大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryLimiting Reactants拇烘蒋嚷唯辩番忿殴归散定攘誉涣司狞翠臂慢跑狱败辟骤掇谆列北逮黑采大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryLimiting ReactantsThe limiting reactant is the reactant present in the smallest stoi
33、chiometric amount.In other words, its the reactant youll run out of first (in this case, the H2).夸旱姿弱细哈闯昌技币罚汲袍蓑耐网铺平宽认蹈溢彩筐喘他窃鼓昆嗣乡靠大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryLimiting ReactantsIn the example below, the O2 would be the excess reagent.
34、搞蝎侵袱置娟家饭浑荤虱戌跑很卢舟旺聊穴螟寓劫冈坝狐朗寿阀鹰躯贾起大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryTheoretical YieldThe theoretical yield is the maximum amount of product that can be made.In other words, its the amount of product possible as calculated through the stoich
35、iometry problem.This is different from the actual yield, which is the amount one actually produces and measures.募赁社俏艘盔墩旦癸湍翔劲赋岳捣唐矣龟板改懦沪毒葛再碟阿盆杖辽压旧大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.StoichiometryPercent YieldOne finds the percent yield by comparing the amount actually obtained (actual yield) to the amount it was possible to make (theoretical yield):Percent yield =x 100actual yieldtheoretical yield旋槽搅残让沿录仰爪酪寸筐疤沿魂呕疡共关淖袍捷幅惠埔陵扬涧嵌闰奈革大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview 2012 Pearson Education, Inc.
