Which way does the reaction move when more acid (H+) is added?

" H2O (1) H + (aq) + OH - (aq) "

a) The reaction moves to the left.

b) The reaction moves to the right.

c) This reaction does not change concentrations.

Answer: option a) the reaction moves to the left.

Explanation.

When the equilibrium of a reaction is disturbed (e. g. modification of reactants or products) the concentrations of the species in equilbrium will change.

The chemical equlibrium is a dynamic equilbrium, which means that at equilibrium the rate of the forward reaction is equal the rate of the backward reaction.

Following Le Chatelier's principle. the addition of one of the species on the right side will cause to increase the speed of the backward reaction to compensate (release) the increase of the concentration of the species by reacting and producing more of the species of the left side.

So, given that the acid (H+) is on the right side, increasing its concentration will cause the formation of more H₂O, which is the reaction moves to the left to restablish the equilibrium (a new equilibrium).

Le Chatelier's principle states that the addition of one of the species on the right side will cause to increase the speed of the backward reaction to compensate the increase of the concentration of the species by reacting and producing more of the species of the left side. So, " H2O (1) H + (aq) + OH - (aq) " reaction move when more acid (H+) is added a) The reaction moves to the left.