Question

Define a buffer. Which buffer is based on breathing? Write the chemical equation.

Answer 1

A buffer is mixture of weak acid (base) and the salt of its conjugate base (acid).

Acidic buffer: CH₃COOH (weak acid) + CH₃COONa

CH₃COO^- is the conjugate base of CH₃COOH

Basic buffer: NH₃ (weak base) + NH₄Cl (NH₄⁺ is the conjugate acid of NH₃).

A buffer can resist small changes in the H⁺ and OH^- concentrations thereby maintaining a constant value of pH of the system.

Breathing or respiration is based on carbonic acid-bicarbonate buffer system which can be shown by the following equilibrium equation:

CO₂ (g) + H₂O (l) <------> H⁺ (l) + HCO₃^- (l)

Respiratory and urinary systems helps in compensating the pH. Increase in H⁺ drives the equilibrium to the left forming more carbondioxide which is eliminated by lungs and   urinary system is responsible for bicarbonate levels in the blood.