问题 填空题

(10分)25时,如果取0.1 mol·L-1HA溶液与0.1 mol·L-1NaOH溶液等体积混合(混合后溶液体积的变化不计),测得混合溶液的pH=8,试回答以下问题:

(1)混合溶液的pH=8的原因(用离子方程式表示):

___________________________________________________________________;

(2)混合溶液中由水电离出的c(H+)_____(填“<”“>”“=”)0.1 mol·L-1 NaOH溶液中由水电离出的c(H+);

(3)求出混合液中下列算式的精确计算结果:

c (Na+)-c (A)= ______________mol·L-1

(4)已知NH4A溶液为中性,又知将HA溶液加到Na2CO3溶液中有气体放出,试推断(NH42CO3溶液的pH_____7 (填“<”“>”“=”);

(5)将相同温度下相同浓度的五种溶液:

①(NH42CO3 ②NH3· H2O  ③(NH42SO4   ④NH4Cl ⑤CH3COONH4

按c(NH4+)由大到小的顺序排列___________________(填序号)。

答案

(1)A+H2OHA+OH  

(2)>  

(3)9.9×107    

(4)>  

(5)CDBA

完形填空
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填空题