Question

How does the pH of a solution change when it is diluted​

Answer 1

Answer:

Adding water to an acid or base will change its pH. Water is mostly water molecules so adding water to an acid or base reduces the concentration of ions in the solution.

When an acidic solution is diluted with water the concentration of H+ ions decreases and the pH of the solution increases towards 7.

To make the pH change by 1, a tenfold dilution is required (eg adding 9 cm3 of water to 1 cm3 acid). The acid is becoming less acidic.

Similarly, when an alkali is diluted with water the concentration of OH- ions decreases. This causes the pH of the alkali to fall towards 7, making the solution less alkaline as more water is added.