Water undergoes various treatments to make it safe for supply as drinking water - Leaving Cert Chemistry - Question 7 - 2021

pH is a measure of the acidity or basicity of a solution, quantified on a scale from 0 to 14. A pH of 7 is considered neutral, values below 7 indicate acidity, and values above 7 indicate basicity. The pH is calculated as the negative logarithm (base 10) of the hydrogen ion concentration:

$pH = - ext{log} [H^+]$

To calculate the pH of a strong acid like HCl, we can use its concentration directly since it dissociates completely in solution. Hence, for a 0.02 M solution:

$pH = - ext{log} [H^+] = - ext{log} (0.02) \approx 1.7$

Thus, the pH is 1.7.

Households should not be supplied with acidic water because it can cause corrosion of plumbing systems, leach harmful metals into the water supply, and adversely affect the taste and quality of the water. Acidic water may also have detrimental effects on appliances and systems that utilize water.

When a base is added to water, the pH of the water increases. This is because bases accept protons (H⁺ ions) from the solution, thereby reducing the concentration of H⁺ ions and consequently raising the pH.