1. pH= -lg[H+]
[H+]=10^-pH=10-11.5 = 3.16 * 10-12
2.pOH=14 - pH=14-11.5= 2.5
pOH=-lg[OH-];
[OH-]=10-2.5 = 3.16*10-3
Answer: 1. 3.16 * 10-12 M
2.3.16*10-3 M