题目

常温下，将pH=a的NaOH溶液与pH=b的醋酸溶液等体积混合后，两者恰好完全反应，则该温度下醋酸的电离平衡常数约为A. 1014-a-2b B. 10 a+b-14 C. 10a-2b D. 10a-2b+14 答案：【答案】A【解析】pH=b的醋酸溶液中c(H+)=c(CH3COOO-)=10-bmol/L，pH=a的NaOH溶液中c(OH-)=c(NaOH)=10a-14mol/L,将两者等体积混合，恰好完全反应，则说明醋酸的物质的量浓度等于NaOH的物质的量浓度，c(CH3COOH)约为10a-14mol/L,故该温度下醋酸的电离平衡常数为1014-a-2b 。答案选A。补全对话。A: 【1】B: A ruler? 【2】A: It’s under the desk.【3】B: Oh, I see. A: Whose ruler is it? Is it Jenny’s ruler?B: 【4】A: Is it Tim’s ruler?B: 【5】 It’s Tim’s desk and Tim has a yellow ruler.A.No, Jenny’s ruler is green.B.Where is it?C.Danny, look at that ruler.D.Yes, it is.E.It’s a yellow ruler.