第1章 物质的聚集状态
1-14 医学上用的葡萄糖(C6H12O6)注射液是血液的等渗溶液,测得其凝固点比纯水降低了0.543 ℃,(1) 计算葡萄糖溶液的百分含量;(2) 如果血液的温度为37 ℃,血液的渗透压是多少? 解:(1) ?Tf?Kf(H2O)?b(C6H12O6)
b(C6H12O6)??Tf/Kf(H2O) ?0.543℃/1.86K?kg?mol ?0.292mol?kg-1-1
w?0.292?180/(0.292?180?1000) ? 0.0499??c?R?T
(2) ?0.292mol?L?1?8.314kPa?L?mol ?753kPa?1?K?1?(273.15?37)K
1-15 孕甾酮是一种雌性激素,它含有9.5%H、10.2%O和80.3%C,在5.00 g苯中含有0.100 g的孕甾酮的溶液在5.18 ℃时凝固,孕甾酮的相对分子质量是多少?分子式是什么?
解:?Tf?Tf?Tf??[278.66?(273.15?5.18)]K?0.33K
?Tf?Kf(苯)?b(孕甾酮)?Kf(苯)?m(孕甾酮)/[M(孕甾酮)?m(苯)]
M(孕甾酮)?Kf(苯)?m(孕甾酮)/[?Tf?m(苯)] ?[5.12?10?0.100/(0.33?5.00)]g?mol ?310.30g?mol?13?1
C∶H∶O = 310.30×80.3%/12.011∶310.30×9.5%/1.008∶310.30×
10.2%/16.00
= 21∶29∶2
所以孕甾酮的相对分子质量是310.30,分子式是C21H29O2。 1-16 海水中含有下列离子,它们的质量摩尔浓度分别为:
b(Cl)?0.57mol?kgb(Na)?0.49mol?kg???1;b(SO42?)?0.029mol?kg?1;b(HCO3?)?0.002mol?kg?1; ;b(Mg2??1)?0.055mol?kg?1;b(K?)?0.011mol?kg?1;
b(Ca2?)?0.011mol?kg?1;
试计算海水的近似凝固点和沸点。
?Tf?Kf(H2O)?b解: ?[1.86?(0.57?0.029?0.002?0.49?0.055?0.011?0.011)]K
?2.17KTf?273.15K?2.17K?270.98K
?Tb?Kb(H2O)?b ?[0.52?(0.57?0.029?0.002?0.49?0.055?0.011?0.011)]K ?0.61KTb?373.15K?0.61K?373.76K
1-17 取同一种溶胶各20.00 mL分别置于三支试管中。欲使该溶胶聚沉,至少在第一支试管加入4.0 mol·L-1的KCl溶液0.53 mL,在第二支试管中加入0.05 mol·L-1的Na2SO4溶液1.25 mL,在第三支试管中加入0.0033 mol·L-1的Na3PO4溶液0.74 mL,试计算每种电解质溶液的聚沉值,并确定该溶胶的电性。 解:第一支试管聚沉值:
4.0mol?L?1?0.53mL?1000/(20.00?0.53)mL?1?1.0?10mmol?L2
第二支试管聚沉值:
0.050mol?L?1?1.25mL?1000/(20.00?1.25)mL?2.9mmol?L?1
第三支试管聚沉值:溶胶带正电。
0.0033mol?L?1?0.74mL?1000/(20.00?0.74)mL?1
?0.12mmol?L第二章 化学反应的一般原理
2-1 苯和氧按下式反应:
C6H6(l)?152O2(g)?6CO2(g)?3H2O(l)
在25 ℃100 kPa下,0.25 mol苯在氧气中完全燃烧放出817 kJ的热量,求C6H6
?的标准摩尔燃烧焓?cH?m和该燃烧反应的?rUm。
1?nB?(?0.25mol)/(?1)?0.25mol 解:????B
?cH?m??rH?m??rH????817kJ0.25mol??3268kJ?mol?1
?rUm??rHm??ngRT ??3268kJ?mol ??3264kJ?mol-1-1???[(6?15/2)?8.314?10?3?298.15]kJ?mol?1
2-2 利用附录Ⅲ的数据,计算下列反应的?rH?。 m(1) Fe3O4(s)?4H2(g)?3Fe(s)?4H2O(g) (2) 2NaOH(s)?CO2(g)?Na2CO3(s)?H2O(l) (3) 4NH3(g)?5O2(g)?4NO(g)?6H2O(g) (4) CH3COOH(l)?2O2(g)?2CO2(g)?2H2O(l)
?rHm?4?fHm(H2O,g)??fHm(Fe3O4,s)???解:(1) ?[4?(?241.8)?(?1118.4)]kJ?mol ?151.2kJ?mol?1?1
(2)
?rHm??fHm(H2O,l)??fHm(Na2CO3,s)?2?fHm(NaOH,s)??fHm(CO2,g) ?[(?285.8)?(?1130.68)?2?(?425.609)?(?393.509)]kJ?mol ??171.8kJ?mol??1?1?????
?rHm?6?fHm(H2O,g)?4?fHm(NO,g)?4?fHm(NH3,g)???(3) ?[6?(?241.8)?4?90.25?4?(?46.11)]kJ?mol ??905.4kJ?mol???1???1
?rHm?2?fHm(H2O,l)?2?fHm(CO2,g)??fHm(CH3COOH,l)(4) ?[2?(?285.8)?2?(?393.509)?(?485.76)]kJ?mol ??872.9kJ?mol?1?1
2-5 计算下列反应在298.15 K的?rH?,?rS?和?rG?,并判断哪些反应能自发mmm向右进行。
(1) 2CO(g)?O2(g)?2CO2(g)
(2) 4NH3(g)?5O2(g)?4NO(g)?6H2O(g) (3) Fe2O3(s)?3CO(g)?2Fe(s)?3CO2(g)
(4) 2SO2(g)?O2(g)?2SO3(g)
?rHm?2?fHm(CO2,g)?2?fHm(CO,g)???解:(1) ?[2?(?393.509)?2?(?110.525)]kJ?mol ??565.968kJ?mol???1???1
?rSm?2Sm(CO2,g)?2Sm(CO,g)?Sm(O2,g) ?[2?213.74?2?197.674?205.138]J?mol ??173.01J?mol???1?1?K?1
?K?1?rGm?2?fGm(CO2,g)?2?fGm(CO,g) ?[2?(?394.359)?2?(?137.168)]kJ?mol ??514.382kJ?mol???1
?1?rGm?0,反应能自发向右进行??? 。??rHm?4?fHm(NO,g)?6?fHm(H2O,g)?4?fHm(NH3,g)(2) ?[4?90.25?6?(?241.818)?4?(?46.11)]kJ?mol ??905.47kJ?mol???1????1
?rSm?4Sm(NO,g)?6Sm(H2O,g)?4Sm(NH3,g)?5Sm(O2,g) ?[4?210.761?6?188.825?4?192.45?5?205.138]]J?mol ?180.50J?mol???1?1?K?1
?K?1?rGm?4?fGm(NO,g)?6?fGm(H2O,g)?4?fGm(NH3,g) ?[4?86.55?6?(?228.575)?4?(?16.45)]kJ?mol ??959.45kJ?mol????1
?1?rGm?0,反应能自发向右进行??? 。??rHm?3?fHm(CO2,g)?3?fHm(CO,g)??fHm(Fe2O3,s)(3) ?[3?(?393.509)?3?(?110.525)?(?824.2)]kJ?mol ??24.8kJ?mol???1????1
?rSm?3Sm(CO2,g)?2Sm(Fe,s)?3Sm(CO,g)?Sm(Fe2O3,s) ?[3?213.74?2?27.28?3?197.674?87.4]J?mol ?15.4J?mol???1?1?K?1
?K?1?rGm?3?fGm(CO2,g)?3?fGm(CO,g)??fGm(Fe2O3,s) ?[3?(?394.359)?3?(?137.168)?(?742.2)]kJ?mol ??29.6kJ?mol????1
?1?rGm?0,反应能自发向右进行。
?rHm?2?fHm(SO3,g)?2?fHm(SO2,g)???(4) ?[2?(?395.72)?2?(?296.830)]kJ?mol ??197.78kJ?mol???1???1
?rSm?2Sm(SO3,g)?2Sm(SO2,g)?Sm(O2,g) ?[2?256.76?2?248.22?205.138]J?mol ??188.06J?mol?K???1?1??1?K?1
?rGm?2?fGm(SO3,g)?2?fGm(SO2,g) ?[2?(?371.06)?2?(?300.194)]kJ?mol ??141.73kJ?mol??1
?1?rGm?0,反应能自发向右进行 。2-7 不用热力学数据定性判断下列反应的?rS?是大于零还是小于零。 m(1) Zn(s)?2HCl(aq)?ZnCl2(aq)?H2(g) (2) CaCO3(s)?CaO(s)?CO2(g) (3) NH3(g)?HCl(g)?NH4Cl(s) (4) CuO(s)?H2(g)?Cu(s)?H2O(l)
解:反应(1),(2)均有气体产生,为气体分子数增加的反应,?rS??0; m反应(3),(4)气体反应后分别生成固体和液体,?rS??0。 m?2-8 计算25 ℃,100 kPa下反应CaCO3(s)?CaO(s)?CO2(g)的?rH?和,?Smrm并判断:
(1) 上述反应能否自发进行?
(2) 对上述反应,是升高温度有利?还是降低温度有利? (3) 计算使上述反应自发进行的最低温度。
?rHm??fHm(CaO,s)??fHm(CO2,g)??fHm(CaCO????3,s)解:(1) ?[?393.509?635.09?1206.92]kJ?mol ?178.32kJ?mol????1??1
?rSm?Sm(CaO,s)?Sm(CO2,g)?Sm(CaCO ?[39.75?213.74?92.9]J?mol ?160.6J?mol?1?13,s)?K?1
?K?1