问题 填空题

银锌碱性蓄电池是一种可以反复充电、放电的装置.电池放电时的反应原理是:Zn+Ag2O+H2O=2Ag+Zn(OH)2

现用该蓄电池电解c(NO3-)=6mol•L-1的KNO3和Cu(NO32的混合溶液500mL,当通电一段时间后,两极均收集到22.4L气体(标准状况)(电解池的电极均为石墨电极).

回答下列问题:

(1)银锌碱性蓄电池的正极反应式为______.

(2)电解过程中,阳极反应式为______;阴极反应式为______.

(3)上述电解过程中共转移电子总数______.

(4)电解得到的Cu的质量为______.

(5)原混合溶液中c(K+)为______.

(6)电解后溶液中c(H+)______4mol/L(选填“<”“=”“>”).

答案

(1)该原电池中,较活泼的金属锌失电子作负极,氧化银作正极,正极上氧化银得电子和水反应生成银和氢氧根离子,电极反应式为:Ag2O+H2O+2e-=2Ag+2OH-

故答案为:Ag2O+H2O+2e-=2Ag+2OH-

(2)电解过程中,阳极上氢氧根放电生成氧气和水,4OH--4e-=2H2O+O2↑;阴极上先是铜离子放电生成铜,当铜离子完全析出时,氢离子放电生成氢气,电极反应式为Cu2++2e-=Cu,2H++2e-=H2(或4H2O+4e-=2H2+4OH-).

故答案为:4OH--4e-=2H2O+O2↑;Cu2++2e-=Cu,2H++2e-=H2(或4H2O+4e-=2H2+4OH-).

(3)电解过程中,阳极上失电子,阴极上得电子,根据氧气与转移电子之间的关系式计算.

设转移电子为X.

4OH--4e-=2H2O+O2↑;

   4NA    22.4L

   X     22.4L    

X=4NA

故答案为4NA

(4)氢氧根离子失去4NA 电子析出22.4L氧气转移电子,氢离子得到2NA电子析出22.4L氢气,所以铜离子得到2NA

电子析出铜单质.

设铜单质的质量是y.

Cu2++2e-=Cu 

   2NA  64g

   2NA y

 y=64g.

故答案为64g.

(5)铜的质量是64g,其物质的量是1mol,则C(Cu2+)=

1mol
0.5L
=2mol/L,c(NO3-)=6mol•L-1;设钾离子的物质的量浓度为z,根据溶液呈电中性,溶液中阴阳离子所带电量相等得,2C(Cu2+)+C(K+)=c(NO3-),所以

C(K+)=c(NO3-)-2C(Cu2+)=2mol/L.

故答案为:2 mol•L-1

(6)根据4OH--4e-=2H2O+O2↑知,生成22.4L氧气需要氢氧根离子4mol,根据2H++2e-=H2↑知,生成22.4L氢气需要氢离子2mol,水电离出的氢离子和氢氧根离子个数相同,所以溶液中氢离子的物质的量是2mol,电解过程中溶液的体积减小,所以c(H+)>

2mol
0.5L
=4mol/L.

故答案为>.

阅读理解

The Aborigines (澳洲土著) have lived in Australia for about 60,000 years. They painted pictures inside caves, and these are the rock paintings that have given us so much information about Aboriginal life. For example, some of the paintings that are about 10,000 years old show men with boomerangs. From this we know that the Aborigines started using boomerangs for hunting at that time. Other pictures show kangaroos, so we know that there were kangaroos at that time.

The Aborigines believed that spirits made people, animals and plants, and that these spirits still live in the earth. For Aborigines, no one can own the earth—the earth belongs to the spirits.

In 1700, there were many Aboriginal groups with a population of 750,000 all over Australia, and there were probably more than 240 different Aboriginal languages. The groups did not have a leader. Instead, things were decided by the older men in a group. People from different groups often travelled hundreds of miles to meet each other.

Aboriginal life changed when an English boat arrived in Australia in 1770. Many Aborigines were killed in the wars that they had with the English. More Europeans came, and they started taking land from the Aborigines. The Europeans also brought new illnesses that killed the Aborigines. The result is that today there are only about 300,000 Aborigines in Australia.

小题1:The Aborigines painted pictures       .

A.on animals’ fur

B.on the land

C.on the tree

D.on the rock小题2:What do you think the Aborigines used boomerangs to do?

A.To paint.

B.To hunt.

C.To fight.

D.To play.小题3:The Aborigines thought        were the most important on the earth.

A.people

B.animals

C.spirits

D.plants小题4:In an Aboriginal group        decided things.

A.the older men

B.the leader

C.the English

D.the Europeans小题5:The number of the Aborigines is small today       .

A.because their living condition was very bad

B.because the English killed a lot of them in the wars

C.because of the new illnesses the Europeans brought them

D.because of the wars and the new illnesses

单项选择题