Question

The pH of a solution is increased from 2 to 4, its H+ concentration will​

Answer 1

$[H^{+}]$ concentration will be decreased  from 0.01 to 0.0001.

Explanation:

pH of aqueous solution is equal to negative log of hydrogen ion $[H^{+}]$ concentration.

                       $pH=-log_{10} [H^{+}]$

or                      $pH=log_{10}\frac{1}{ [H^{+}]}$

or                           $pH\alpha \frac{1}{ [H^{+}]}$

From the above relation we found that on increase in pH, hydrogen ion concentration is decreases in solution.

In question pH of solution is change from 2 to 4.

So, At            $pH=2$       $[H^{+}]_{1} =10^{-2}=0.01$

                     $pH=4$     $[H^{+}]_{2} =10^{-4}=0.0001$

$[H^{+}]_{1}$ to $[H^{+}]_{2}$ concentration of hydrogen ion is decreases from 0.01 to 0.0001. This confirms that on increase in pH of solution, $[H^{+}]$ concentration will be decreased.

Answer 2

If the pH of a solution is increased from 2 to 4, its H+ concentration will​ DECREASE.

- More the pH, the lesser the H+ concentration.

- When pH is 2, the H+ concentration is given as:

[H+] = 10^(-pH) = 10⁻² M = 0.01 M

- When pH is 4, the H+ concentration is given as:

[H+] = 10^(-pH) = 10⁻⁴ M = 0.0001 M

- It is clear from above that H+ concentration will​ decrease on increasing pH.