Question

The pH of a solution is 5.0. To this solution sufficient acid is added to decrease the pH to 2.0. Then the hydrogen ion concentration increases by:

• A. 1000.0
• B. 1000.00
• C. 1000

Answer 1

Answer: (A), (B), (C)

We know $pH=-\log \left[H^{+}\right]$
When pH = 5,
$\left[H^{+}\right]={10}^{-pH}={10}^{-5}M$
The pH of solution is decreased to 2.
when pH = 2,
$\left[H^{+}\right]={10}^{-pH}={10}^{-2}M$
The change in concentration of $\left[H^{+}\right]$ is ${10}^{-2}/{10}^{-5}={10}^3=1000$
It is increased by 1000 times