Question

What is the `pH` of the following solutions:
a. `10^(-7)M NaOH` b. `10^(-8)M NaOH`
c. `10^(2) M NaOH`
A. `7.04`
B. `8`
C. `6`
D. `6.96`

Answer 1

Correct Answer - A
`[OH^(-)]` from `NaOH = 10^(-8) M`
`[OH^(-)]` from water `= 10^(-7)`
Total `[OH^(-)] = 10^(-7) + 10^(-7)`
`[OH^(-)] = 1.1 xx 10^(-7)`
`P^(OH) = -log_(10)[OH^(-)]`
`=-log_(10) 1.1 xx 10^(-7) = 6.96`
`P^(H) + P^(OH) = 14`
`P^(H) = 14-6.96 = 7.04`