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1、,Chapter 3 Stoichiometry: Calculations with Chemical Formulas and Equations,John D. Bookstaver St. Charles Community College Cottleville, MO,Lecture 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-preview, 2012 Pearson Education, Inc.,Law of Conservation o
2、f 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, 1789,半枕竞齿
3、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.,Chemical Equations,Chemical 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-preview, 2012 Pears
4、on Education, Inc.,Anatomy of a Chemical Equation,CH4(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.,Anatomy of a Chemical Equation,CH4(g) + 2O2(g) CO2(g) + 2H2O(g),Reactants appear on the left side of
5、 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.,Anatomy of a Chemical Equation,CH4(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-p
6、review大学化学（梁永晔）03-lecture-preview, 2012 Pearson Education, Inc.,Anatomy of a Chemical Equation,CH4(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-le
7、cture-preview, 2012 Pearson Education, Inc.,Anatomy of a Chemical Equation,CH4(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-preview, 2012 Pearson Education, Inc.,Subscripts and Coefficie
8、nts Give Different Information,Subscripts 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 Pearson Education, Inc.,Reaction 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
9、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.,Combination Reactions,Examples: 2Mg(s) + O2(g) 2MgO(s) N2(g) + 3H2(g) 2NH3(g) C3H6(g) + Br2(l) C3H6Br2(l),In combination reactions 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
10、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.,In a decomposition reaction one substance breaks down into two or more substances.,Decomposition Reactions,Examples: CaCO3(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
11、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.,Combustion Reactions,Examples: CH4(g) + 2O2(g) CO2(g) + 2H2O(g) C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(g),Combustion reactions are generally rapid reactions that produce a flame. Combustion reactions most ofte
12、n 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.,Formula Weights,福夸严诛挞讼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,
13、 Inc.,Formula 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 amu) + Cl: 2(35.453 amu) 110.99 amu Formula 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
14、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.,Molecular Weight (MW),A molecular weight is the sum of the atomic weights of the atoms in a molecule. For the molecule ethane, C2H6, the molecular weight would be,C: 2(12.011 amu),30.070 amu,+ H: 6(1.00
15、794 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.,Percent Composition,One can find the percentage of the mass of a compound that comes from each of the elements in the compound by using this equation:,乌啮入栅敏障纯司柞综洗料洋佰缺奏寥粟馏铱秋还负
16、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.,Percent Composition,So the percentage of carbon in ethane is,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.,Moles,搓批谢脚娘盟让溢氖撕凡顿梨朱焉锑纵忘朽匪氛鸦
17、将稗祈撞桅硒萨屁家屁大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview, 2012 Pearson Education, Inc.,Avogadros Number,6.02 x 1023 1 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.,Molar Mass,By definit
18、ion, 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-lect
19、ure-preview大学化学（梁永晔）03-lecture-preview, 2012 Pearson Education, Inc.,Using Moles,Moles 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.,Mole Relationships,One mole o
20、f 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-preview, 2012 P
21、earson Education, Inc.,Finding 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.,Calculating Empirical Formulas,One can calculate the empirical formula from the percent composition.,五思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
22、大学化学（梁永晔）03-lecture-preview大学化学（梁永晔）03-lecture-preview, 2012 Pearson Education, Inc.,Calculating Empirical Formulas,The compound para-aminobenzoic acid (you may have seen it listed as PABA on your bottle of sunscreen) is composed of carbon (61.31%), hydrogen (5.14%), nitrogen (10.21%), and oxygen (2
23、3.33%). 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.,Calculating Empirical Formulas,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 Educati
24、on, Inc.,Calculating Empirical Formulas,Calculate the mole ratio by dividing by the smallest number of moles:,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.,Calculating Empirical Formulas,These are the subscripts for the empirical
25、 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.,Combustion Analysis,Compounds containing C, H, and O are routinely analyzed through combustion in a chamber like the one shown in Figure 3.14. C is determined from t
26、he 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-preview, 2012 Pearson Education, Inc.,Stoichiometric Calculations,The coefficie
27、nts 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.,Stoichiometric Calculations,Starting with the mass of Substance A, you can use the ratio of the coeffic
28、ients 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 Pearson Education, Inc.,Stoichiometric Calculations,Starting with 1.00 g of C6H12O6 we calculate t
29、he moles of C6H12O6 use the coefficients to find the moles of H2O and 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-preview大学化学（梁永晔）03-lecture-preview, 2012 Pearson Education, Inc.,Limiting 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
30、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.,Limiting Reactants,The limiting reactant is the reactant present in the smallest stoichiometric 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
31、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.,Limiting Reactants,In the example below, the O2 would be the excess reagent.,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.,Theoretical Yi
32、eld,The 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 stoichiometry 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
33、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.,Percent Yield,One finds the percent yield by comparing the amount actually obtained (actual yield) to the amount it was possible to make (theoretical 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,