Question
Question: 10<sup>–6</sup> M NaOH is diluted by 100 times. The pH of diluted base is –...
10–6 M NaOH is diluted by 100 times. The pH of diluted base is –
A
Between 6 and 7
B
Between 10 and 11
C
Between 7 and 8
D
Between 5 and 6
Answer
Between 7 and 8
Explanation
Solution
After dilution, [OH–] = 10–8 M
or [H+] = 10–6 M. pH cannot be 6 because total
[OH–] = 10–7 + 10–8 = 10–7 (1 + 0.1)
= 10–7 × 1.1 or [H+] = 10–14/(10–7 × 1.1)
= 9.09 × 10–8
\ pH = 8 – log 9.09 = 8 – 0.9546 = 7.0454.