问题 选择题

物质的量浓度都为0.1 mol·L-1的CH3COOH与NaOH溶液等体积混合后,下列关系式不正确的是

A.c(Na+)>c(CH3COO)>c(H+)>c(OH)

B.c(Na+)+c(H+)=c(OH)+c(CH3COO)

C.c(OH)=c(H+)+ c(CH3COOH)

D.c(CH3COOH)+ c(CH3COO)= c(Na+)

答案

答案:A

题目分析:CH3COOH与NaOH溶液等浓度等体积混合后二者恰好完全发生反应:CH3COOH+NaOH= CH3COONa + H2O,得到醋酸钠溶液。A.由于醋酸钠是强碱弱酸盐,醋酸根离子发生水解反应CH3COO- + H2O:CH3COOH+OH-.而消耗所以c(Na+)>c(CH3COO),破坏了水的电离平衡,促使水继续电离,最终当溶液达到平衡时C(H+)<C(OH-)。盐水解的程度是很微弱的,水电离产生的离子的浓度远小于盐的电离,所以c(CH3COO)> c(OH)。因此错误。B.根据溶液呈电中性原则,阳离子所带的正电荷总数与阴离子所带的负电荷总数相等可得c(Na+)+c(H+)=c(OH)+c(CH3COO)。正确。C.由于醋酸根离子发生水解反应CH3COO- + H2O  CH3COOH+OH-使溶液显碱性,所以C(OH-)(水)=C(H+)(剩余)+C(H+)(反应)= C(H+)+C(CH3COOH).故正确。D.根据物料守恒可得c(Na+)= c(CH3COO)(剩余)+ c(CH3COO)(消耗)= c(CH3COO)+ c(CH3COOH)。正确。

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     Water, it's a problem for the whole world.
     A bottle (瓶) of water may not seem like much to us, __1__ it can help the people who live in
drought-hit (遭受旱灾的) areas in China.
     In the past few months, many places in southwest China have __2__ a serious drought. There has
been very little __3__ since last autumn. More than 20 million people are __4__ trouble finding safe
drinking water.
     After learning about the drought, many people around the country helped by __5__ away water,
money and other resources (资源) to the people there.
     Last week, the Young Pioneers and the Communist Youth League in China called on (号召) each
student to give one bottle of water to the drought-hit area. In Xi'an, 900 students bought over 100 bottles
of water __6__ their pocket money. They also wrote their __7__ on the bottles. "I hope you get more
rain there. I hope you are happy."
     A bottle of water isn't much, but thousands of bottles will be very __8__. The serious drought has
also made students __9__ the importance of saving water. One student said, "I have decided to take a
shower twice a week __10__ every day to save water."
( )1. A. unless  
( )2. A. bought
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( )7. A. plans
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( )9. A. think
( )10. A. instead
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B. giving
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B. beautiful
B. realize
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C. but    
C. studied   
C. snow      
C. having    
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