问题 问答题

已知一定质量的硫与100mL某浓度的KOH溶液恰好完全反应,其反应方程式为:3S+6KOH(浓)

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2K2S+K2SO3+3H2O,若化合价升高的硫元素为1.6g,求该KOH溶液的物质的量浓度?

答案

化合价升高的硫原子的物质的量为

1.6g
32g/mol
=0.05mol,化合价升高生成亚硫酸根,硫元素化合价降低生成硫离子,令化合价降低的硫原子的物质的量为xmol,根据电子转移守恒有x×[0-(-2)]=0.05×(4-0),解得x=0.1,所以参加反应的硫的总的物质的量为0.05mol+0.1mol=0.15mol,根据方程式3S+6KOH(浓)
 △ 
.
 
2K2S+K2SO3+3H2O可知,参加反应的KOH的物质的量为1.15mol×
6
3
=0.3mol,故KOH的物质的量浓度为
0.3mol
0.1L
=3mol/L,

答:该KOH溶液的物质的量浓度3mol/L.

阅读理解与欣赏
阅读理解

Australia is the smallest continent in the world. It is a little smaller than China. It is on the Southern Hemisphere(半球)of the earth. Australia is big, but its population is small. The population of Australia is nearly as large as that of Shanghai.

Enough laws have been made to fight against pollution. The cities in Australia have little air or water pollution. The sky is blue and the water is clean. You can clearly see fish in the rivers. Plants grow very well.

Last month we visited Perth, the biggest city in Western Australia, and went to a wild flower exhibition. There we saw large numbers of wild flowers on show, most of which we had never seen before. We had a wonderful time. Perth is famous for its beautiful wild flowers. Every year in spring Perth has wild flower exhibitions. After visiting Perth, we spent a day in the countryside. We sat down and had a rest near a path at the foot of a hill. It was quiet and we enjoyed ourselves very much. When we heard bells ringing at the top of the hill, we looked up, but what we saw made us pick up all our things and run back to our car as quickly as we could. There were about three hundred sheep coming towards us along the path.

Australia is famous for its sheep and kangaroos(袋鼠). After a short drive from any town, you will find yourself among the white sheep. Sheep, sheep, everywhere you can see sheep.

小题1:Which country is the writer most possibly from?

A.Japan

B.Canada

C.China

D.America小题2:Which of the following statements is not true according to the passage?

A.Australia has enough laws to fight against pollution.

B.Perth is the biggest city in Australia.

C.The wild flowers in Perth must be different from what the author sees in his/her country.

D.The author enjoyed his/her visit in the countryside.小题3:The underlined word “exhibition” in the third paragraph probably means_______.

A.a public show for people to visit

B.a market where you can buy all kinds of flowers

C.a place where all kinds of flowers are grown

D.a field where there are flowers and animals小题4:From the passage we know Perth is famous for ____

A.its population

B.its size

C.its kangaroos

D.its wild flowers