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问题 问答题

（1）若要配制100mL0.1mo1•L-1Na2SO4溶液，需称量Na2SO4的质量为______g．

（2）将2240mL氨完全溶于水配成100mL溶液，氨水中NH3的物质的量浓度为______mol•L-1．（不考虑NH3与H2O的反应）

（3）实验室里常用固体氯化铵与足量熟石灰加热制取氨．若需要2240mL（标准状况）氨，求至少需要氯化铵的质量．

答案

（1）配制100mL0.1mo1•L-1Na2SO4溶液，需称量Na2SO4的质量为：0.1L×0.1mol/L×142g/mol≈1.4g，故答案为：1.4；

（2）2240mL氨气的物质的量为：

2.24L
22.4L/mol
=0.1mol，

氨水的物质的量浓度为：

0.1mol
0.1L
=1mol/L，

故答案为：1；

（3）令生成2240mL（标准状况）氨气需要氯化铵的质量为mg，则：

2NH4Cl+Ca（OH）2

 △ 
.
 
CaCl2+2NH3↑+2H2O

107g                    44.8L

mg                      2.24L

所以107g：mg=44.8L：2.24L

解得：m=5.35

答：需要氯化铵5.35g．

完形填空
On a snowy evening, a rich lady was standing by the road. She was very worried. Her      had broken down. Just then a poor man named Robert came. He was on his      back home from work as usual. The lady wondered, "Is the man going to       me? He looks very cold and hungry." But to her surprise,      stopped and said with a smile, "Can I help you, madam?" After forty       , the car was at last fixed by Robert. The lady wanted to pay him." No, that's       , madam." he said, "I was just helping someone in      . If you really want to pay me back, I hope      you see someone in need, you should give him a hand." A few minutes later, the lady      a shabby (破旧的)house by the road. She remembered Robert's words, so she stopped. The hostess(女主人) warmly asked her      . The lady could see that was a       family and that they needed help. When the hostess was making tea in the kitchen, the lady       on a table 500 dollars and went away quietly. Robert came home later than before, thinking how       their life was. His wife was pregnant(怀孕) and the baby was to be born the next month but there was not       money. His wife went up to him, gave him a kiss and said softly, "Don't worry, dear! Everything's going to be all     . A stranger has helped us out." Let's always be ready to help others because helping others is helping ourselves.
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