Question

The pH of a solution is 5.0. To a 10 ml of this

solution, 990 ml of water is added. Then the pH
V7 6.96
of the resulting solution is
1) 7 2) 8
3) 9
UN, & VN​

Answer 1

pH = 7

Step-by-step explanation:

pH is defined as -log [H⁺]. In a solution of pH 5:

pH = -log [H⁺]

10^(-5) = [H⁺]

1x10⁻⁵M = [H⁺].

Then, this solution is diluted from 10mL to 1000mL (990mL of water + 10mL of the original solution). That means the solution is diluted:

1000mL / 10mL / 100 times.

If [H⁺] before dilution was 1x10⁻⁵M, after dilution will be:

1x10⁻⁵M / 100 = 1x10⁻⁷M

And pH:

pH = -log [H⁺]

pH = -log 1x10⁻⁷M

pH = 7