What is the pH of 7.51x10^-8 mol/L HCl(aq)?

题目

What is the pH of 7.51x10^-8 mol/L HCl(aq)?
Give your answer accurate to two decimal places.
Note:You are dealing with a very dilute solution of a very strong acid.Think carefully!One approach is to write down mass and charge balance equations and all relevant equilibrium constant expressions.(Hint:The relevant equilibrium is the self-ionization of water.)

答案

假设由水电离的c(H+)=x,则c(OH-)=x
盐酸电离的氢离子浓度=c(HCl)=7.51x10^-8
溶液中的氢离子浓度=x+7.51x10^-8
溶液中的氢氧根浓度=x
在水溶液中,总氢离子浓度乘以总氢氧根浓度等于水的离子积
所以x(x+7.51x10^-8)=10^(-14)
可以解出x
进而求出x+7.51x10^-8
进而算出pH值
没有计算