中南大学物化课后习题答案 10章 电极过程.doc

第10章电极过程1用间接方法求得298.15k时，反应h2?o2 = h2o（l）236.65 kjmol-1试问298.15k时，非常稀的硫酸溶液的分解电压是多少?设用的是可逆电极，并且溶液搅拌得很好。 （答案：1.226v）解： = - zfe u分 = e理 = e= 2298.15k时低电流密度电解稀硫酸水溶液，用银作两极的电极材料，和用光滑铂作两极材料，试分别确定其分解电压(已知在银电极上h20.87 ，o20.96v，在光滑铂电极上h20.09，o20.45v。并设稀硫酸水溶液中ah2o1)。 （答案：3.059v；1.769v）解： 电解稀硫酸水溶液，就是电解水，其理论（可逆）分解电压为1.229，考虑极化作用，则其实际分解电压 = 理论（可逆）分解电压 + 超电压，故，用ag作电极：u分 = 1.229 0.87 0.96 = 3.059 v用pt作电极：u分 = 1.229 0.09 0.45 = 1.769 v3某溶液中含10-2moldm-3 cdso4，10-2moldm-3 znso4和0.5moldm-3h2so4，把该溶液放在两个铂电极之间，用低电流密度进行电解，同时均匀搅拌，试问哪一种金属将首先沉积在阴极上?当另一种金属开始沉积时，溶液中先析出的哪一种金属所剩余的浓度为多少?（答案：6.6510-15 moldm-3）解： （1） 在此溶液中，而查表知：，一定有：， 故金属cd先析出。（2） 在金属锌析出时cd2+的浓度应满足关系：(-0.4026) + 0.02958 lg ccd2+ = (-0.7628) + 0.0296lg（0.01）解得：ccd2+ = 6.6510-15 moldm-34电解某溶液在阴极上有zn沉积，h2在zn上的超电压为0.72v，欲使溶液中zn2+的浓度降到10-4moldm-3，阴极仍不析出h2气，溶液的ph值最小应控制为多少?（答案：2.7）解：当czn2+= 1.010-4moldm-3时，有析出h2时，有eh+/h2 = (-0.05916)ph-0.72不让h2析出时，需要：eh+/h2 ezn2+/zn即：(-0.05916)ph - 0.72 (-0.8811)解得： ph 2.75298.15k电解精炼铜的酸性溶液内含铜st1:chmetcnv tcsc=0 numbertype=1 negative=false hasspace=false sourcevalue=30 unitname=g30gdm-3，离子活度系数，若电解液中含有杂质银，试问要得到精铜，电解液中银含量最大不能超过何值(设电积时铜的超电压可以忽略，最大银含量时ag+的)? （答案：2.5410-8 moldm-3）解：铜中不含ag，则，即：0.2644解得： 8.9810 -9 moldm-36 电解ph5的cdcl2溶液时，cd2+的浓度为多少时h2开始析出? 已知h2的超电压为0.48v。（答案：2.31610-3 moldm-3）解：，氢气析出时，有： 2.417510-13 moldm-37将含0.05moldm-3硫酸的0.1moldm-3硫酸铜溶液于298.15k进行电解，当两价铜离子的浓度减少到110-7moldm-3时，阴极电势为何值?在不让氢析出的条件下，阴极电势可能的值为多少(设电解液的ph0.15，氢在铜上的超电压为0.33v)?（答案：0.133；0.3389v）解：铜的阴极电势为：不析出h2的最低阴极电势为：8用电解沉积cd2+ 的方法分离某中性水溶液中的cd2+和zn2+。已知该溶液中cd2+和zn2+的浓度均为0.1molkg-1，h2在cd和zn上的超电压分别为0.48 v和0.70v。试问在298.15k时分离效果怎样?有没有氢析出干扰(设cd2+和zn2的活度近似等于浓度)?（答案：310-21 moldm-3；无）解： 在cd电极上：在zn电极上：而cd和zn的析出电势为：cd和zn的析出电势都大于h2的析出电势，所以没有h2析出干扰，且cd优先析出当zn析出时，cd2+浓度应该降为：，解得6.6410-14 moldm-39某溶液中含zn2+和fe2+，活度均为1。已知氢在铁上的超电压为0.4v，如欲使离子析出次序为fe、h2、zn，则298.15k时溶液的ph值最大不得超过多少?在此ph溶液中，h2开始析出时fe2+的活度降为若干?（答案：6.14；1.2210-11）解：efe2+/fe= -0.4402 + 0.0296lgcfe2+= -0.4402 + 0.0296lg1 = -0.4402 v ezn2+/zn= -0.7628 + 0.0296lgczn2+= -0.7628 + 0.0296lg1 = -0.7628 v 要使h2先与zn析出，则：e（h2，析）ezn2+/zne（h2，析）= -0.05916ph-0.4-0.7628ph6.13 h2析出时，fe2+活度应满足关系：-0.4402 + 0.02958lgfe2+-0.7628 fe2+= cfe2+ 1.2410-1110在0.50molkg-1cuso4及0.01molkg-1h2so4的溶液中，使cu镀到铂极上，若h2在cu上的超电压为0.23v，当外电压增加到有h2在电极上析出时，试问溶液中所余cu2+的浓度为多少?（答案：5.50410-20molkg-1）解： cu与h2同时析出时，有：molkg-111外加电压使下面电解池发生电解作用： ptcdcl2（1molkg-1），niso4（1molkg-1）pt 当外加电压逐渐增加时，电极上首先发生什么反应?此时外加电压至少为多少(设不考虑超电压，电解质活度系数均为1，t298k )?（答案：析ni；析cl2；1.590v）解：电解时，阳极析出cl2，阴极析出ni（ 此时阴极实际析出的仍是h2阳极： 此时阳极实际析出的是cl2。以下是大学体验英语综合教程2(第三版)课后翻译答案unit11. 任何年满18岁的人都有资格投票。(be eligible to, vote)answer:anyone over the age of 18 is eligible to vote.2. 每学期开学前，这些奖学金的申请表格就会由学校发给每一个学生。(apply for, scholarship)answer:a form to apply for these scholarships is sent by the university to every student before the start of every semester.3. 遵照医生的建议，我决定戒烟。(on the advice of)answer:on the advice of my doctor, i decided to give up smoking.4. 公园位于县城的正中央。(be located in)answer:the park is located right in the center of town.5. 这所大学提供了我们所需的所有材料和设备。(facilities)answer:the university provides all the materials and facilities we desire.1. 他们花了多年的时间寻找内心的平静，但是收效甚微。(search for)answer:they spent many years searching for peace of mind, but with little success.2. 这种新药的成功研制已经使许多疾病的治疗发生了根本性的变革。(revolutionize)answer:the successful development of the new drug has revolutionized the treatment of many diseases.3. 由于这个国家的经济不景气，这家公司濒于破产。(on the edge of)answer:the company is on the edge of bankruptcy due to the economic depression in the country.4. 大学毕业后他成为了一名护士。他认为护士这一职业可能很有发展前途。(rewarding)answer:he became a nurse after college. he thought nursing could be a very rewarding career.5. 他像往常一样在文件上签了名。(just as)answer:he signed his name on the paper just as he has always done it.unit21. 警察们正忙着填写关于这场事故的各种表格。(fill out)answer:the policemen are busy fi lling out forms about the accident.2. 我想在还车之前把油箱加满。(fill up, fuel tank)answer:i want to fi ll up the fuel tank before returning the car.3. 如果你要投诉，最好遵循正确的程序。(follow the procedure)answer:if you want to make a complaint, youd better follow the correct procedure.4. 要不是约翰帮忙，我们绝不会这么快就完成实验。(without)answer:we couldnt have fi nished the experiment so soon without johns help.5. 暴风雨之后，岸边的人们焦急地搜索湖面以期发现小船的踪迹。(scan for)answer:after the storm, the people on the shore anxiously scanned the lake for any sign of the boat.1. 这个国家不大，但是在国际事务中它却发挥着重要作用。(play a role)answer:this country is not big, but it plays an important role in international affairs.2. 正是在我叔叔的帮助下，我得以克服困难，按时完成了任务。(it is . that)answer:it was with the help of my uncle that i overcame the difficulty and completed the assignment in time.3. 毕业时他决定留在北京，而他最好的朋友却选择了去西藏。(while)answer:while he decided to stay in beijing upon graduation, his best friend chose to go to tibet.4. 在这次校园英语演讲比赛中，我们班的玛丽获得了第三名。(come in)answer:in this campus english speaking contest, mary from our class came in third.5. 你应该知道学习弹钢琴需要有时间，有金钱，还要有毅力。(as well as)answer:you should know that it takes time, money as well as perseverance to learn to play the piano.unit31. 我发现量入为出地过日子越来越难了。(increasingly)answer:i find it increasingly difficult to live within my income.2. 现代政治家们都试图以电视讲话来影响普通百姓。(reach out)answer:modern politicians try to reach out to ordinary people in their tv speeches.3. 应该帮助学生对人生采取积极的态度。(adopt)answer:pupils should be helped to adopt a positive attitude to life.4. 希望全班同学参加这些讨论。(participate in)answer:everyone in the class is expected to participate in these discussions.5. 如果你犯了罪就必须受到惩罚。(crime)answer:if you commit a crime you must expect to be punished.1.儿子的死让老妇人变得麻木痴呆了。(numb)answer:the old woman was numbed by her sons death.2.身处所有这些烦恼之中，他依然能保持乐观。(in the midst)answer:in the midst of all troubles, he managed to remain cheerful.3. 虽有困难，他们还是设法坚持试验下去。(carry on)answer:they managed to carry on their experiments in spite of the difficulties.4.我们必须淘汰不合格的申请人。(weed out)answer:we have to weed out unqualified applicants.5. 医生要他减少抽烟。(cut down on)answer:the doctor told him to cut down on smoking.unit41.她在公共汽车站一直等到末班车进站。(come in)answer:she waited at the bus stop until the last bus came in.2.如果我们能帮得上忙，尽管和我们联系。(contact)answer:if there is any way we can be of assistance, please do not hesitate to contact us.3 .他需要多少船务人员才能使他的游艇航行？(crew, yacht)answer:how many crew does he need to sail his yacht?4 .虽然她的新书没有上一本好，但是我还是喜欢它。(not quite as)answer:i enjoyed her new book though its not quite as good as her last one.5 .我从未遇到过如此善良的人。(never before)answer:never before have i met such a kind person.1.公共汽车放慢速度并停下，让那位乘客上车。(slow down)answer:the bus slowed down and stopped to allow the passenger to get on board.2.许多车子都驶过去了，可是没有一辆愿意让我们搭便车。(roll by)answer:many vehicles rolled by, but no one offered us a ride.3 .请勿践踏草地。(get off)answer:please get off the grass.4.他按妻子的吩咐，一下班就去了市场。(make ones way)answer:he made his way to the marketplace right after work, as his wife had asked him to do.5 .值得庆幸的是，史蒂夫 (steve) 从自行车上摔下来时没有摔断骨头。(luckily)answer:luckily, steve didnt break any bones when he fell off his bike.unit51. 我们得把感情放在一边，从专业的角度来对待这件事。(from a professional standpoint)answer:we have to put aside our emotions and take it from a professional standpoint.2. 这部戏非常精彩，我很快就沉浸于激动人心的剧情之中。(lose oneself in)answer:the play was so wonderful that i soon lost myself in the excitement of it.3 .她没有什么爱好除非你把看电视也算是一种爱好。(unless)answer:she hasnt got any hobbies unless you call watching tv a hobby.4. 他说他是直接从市长本人那里得到这个信息的。(first-hand)answer:he said that he had got the information first-hand from the mayor himself.5 .既然你不能回答这个问题，我们最好问问别人。(since)answer:since you cant answer the question, perhaps wed better ask someone else.1. 由于公共汽车司机突然刹车，旅客们都不由自主地向前摔倒。(brake, pitch forward)answer:all the passengers pitched forward because the bus driver braked sharply.2. 这个协议将冲破对自由贸易设置的障碍。(break through, obstacle)answer:this agreement will break through the obstacles to free trade.3 .我刚放下叫出租车的电话，车就来了。(soon after)answer:the taxi arrived soon after i rang for it.4. 在过去，不管我什么时候到家，我父母总会等我。(no matter)answer:my parents always waited up for me no matter what time i got home.5 .由于没有一方愿意让步，两个公司之间的对话完全破裂了。(break down)answer:talks between the two companies completely broke down, because neither of them wanted to give in.unit61. 那件工作很难做，不过我想试试看。(have a shot)answer:its a difficult job, but id like to have a shot.2. 这是一本关于商务实践而非理论的书。(as opposed to)answer:this is a book about business practice as opposed to theory.3. 社会活动从未耽误她的学习。(in the way)answer:social activities never get in the way of her studies.4. 直到1911年人们才发现第一种维生素。(it is not until . that)answer:it was not until 1911 that the first of the vitamins was identified.5. 尽管年事已高，爷爷每天还帮忙做家务。(despite)answer:despite advanced years, grandpa helps do housework every day.1. 我们的婚姻很幸福，但我们也曾经历过许多坎坷。(ups and downs)answer:our marriage is happy but weve had many ups and downs.2. 许多外语教师常常在课堂上自顾自地讲得太多。(be inclined to)answer:many teachers of foreign languages are inclined to talk too much themselves in class.3. 那位著名演员每天早晨锻炼一小时以保持健康。(work out)answer:the famous actor keeps fit by working out for an hour every morning.4. 与他促膝长谈之后，她的怀疑消失了。(melt away)answer:after a long heart-to-heart talk with him, her suspicion melted away.5. 目前我们没有职位空缺，但我们肯定会记住您的申请。(keep in mind)answer:we have no vacancies now, but well certainly keep your application in mind.unit71. 他并不后悔说过的话，只是觉得他完全可以不用这种方式表达。(could have done)answer:he did not regret what he had said but felt that he could have expressed it differently.2. 我们最好等到12月14日。那时大卫已考完试，就能和我们一起去度假了。(will have done)answer:wed better wait till 14 december. david will have had his