Question

Using Le Chateliers principles of equilibrium, what is the effect on blood pH of a sudden influx of increased metabolic carbon dioxide? Using a similarly simple relativistic approach, what would be the effect on pH upon expulsion of CO2 gas from the lung?

Answer 1

1) Due to sudden influx of increased metabolic carbon dioxide, carbonic acid will be formed.

With increase in the concentration of carbon dioxide, the equilibrium will shift to right and the concentration of carbonic acid will increase. This is in accordance with Le Chateliers principles of equilibrium, according to which, a system at equilibrium tries to resist any change. When concentration of reactant is increased, the equilibrium will shift in the forward direction so as to nullify the effect of increase in the concentration.

Due to dissociation of carbonic acid, the hydrogen ion concentration will increase.

With increase in hydrogen ion concentration, pH will decrease.

2) Upon expulsion of CO2 gas from the lung, the equilibrium for the formation of carbonic acid will shift in the backward direction. Due to this, the equilibrium for the dissociation of carbonic acid will shift in the backward direction. Due to this, hydrogen ion concentration will decrease and pH will increase.