CAPE Chemistry Unit 1 · 2015 · Paper 2 · Question 5(a)

A buffer consisting of H₂PO₄⁻ and HPO₄²⁻ helps control the pH of physiological fluids. Many carbonated soft drinks also use this buffer system.

Using the buffer system mentioned above, describe how the solution maintains an almost constant pH even when small amounts of acid or alkali are added to the solution.