25 ℃时,浓度均为0.2 mol/L的NaHCO3和Na2CO3溶液中,下列判_爱下问搜题

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问题选择题

25 ℃时,浓度均为0.2 mol/L的NaHCO₃和Na₂CO₃溶液中,下列判断不正确的是(　　)

A．均存在电离平衡和水解平衡

B．存在的粒子种类相同

C．c(OH^-)前者大于后者

D．分别加入NaOH固体,恢复到原温度,c(C)均增大

答案

答案：C

本题主要考查盐类的水解和弱电解质的电离。NaHCO₃和Na₂CO₃溶液中都存在盐的水解平衡和水的电离平衡,A正确;HC水解和电离后与C水解后的粒子种类一样,此时两溶液中均存在:HC、C、H₂CO₃、OH^-、Na⁺、H⁺、H₂O,B正确;因为C水解程度大于HC,所以Na₂CO₃溶液碱性更强,C错误;加入NaOH固体,前者因OH^-与HC 反应而使c(C)增大,后者因OH^-抑制C的水解而使c(C)增大,D正确。

完形填空

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B．In conclusion

B．expressions

问答题

(3)谈谈对材料3的实践观的理解。