Question 949101
Simply use the formula.

{{{-log(10,(2.3*10^(-5)))}}}


{{{-log(10,2.3)-log(10,(10^(-5)))}}}


{{{-log(10,2.3)-(-5)log(10,10)}}}


{{{-log(2.3)+5}}}


{{{-0.362+5}}}


{{{highlight(pH=4.64)}}}