如图装置电解一段时间,当某极析出0.32gCu时,I、Ⅱ、Ⅲ中溶液pH分

如图装置电解一段时间,当某极析出0.32gCu时,I中溶液pH分别为 (溶液足量,体积均为100mL且电解前后溶液体积变化及气体的溶解忽略不计)()

    A             1371            B 1272        C 1713 D 7131

答案

考点  电解原理.

分析:  由离子放电顺序可知,电解时,I中溶液电极方程式分别为2KCl+2H2O2KOH+H2↑+Cl22H2O2H2↑+O22CuSO4+2H2O2Cu+O2↑+2H2SO4,由铜的质量计算转移电子的物质的量,进而计算各溶液的pH

解答:  解:nCu==0.005mol,由电极反应Cu2++2e=Cu可知转移电子为0.01mol

电解时,I中溶液电极方程式分别为2KCl+2H2O2KOH+H2↑+Cl22H2O2H2↑+O22CuSO4+2H2O2Cu+O2↑+2H2SO4

I中生成0.01molOHcOH==0.1mol/LpH=13

电解水,溶液呈中性,pH=7

中生成0.01molH+cH+==0.1mol/LpH=1

故选A

点评:  本题考查电解原理,侧重于学生的分析能力和计算能力的考查,为2015届高考高频考点,难度中等,注意把握离子的放电顺序以及电解方程式的书写,为解答该题的关键.

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