What influence does a decrease in reactant concentration have on the system which is in equilibrium?
Equilibrium will shift to increase the reactant concentration.
According to Le Chatelier's principle if there is a change in concentration, pressure or temperature of a system in equilibrium then the system will readjust itself to counteract the change and attain the equilibrium.
In the given equation, the concentration of the reactant is decreased. The system will readjust itself to increase the reactant concentration. A backward reaction will be favoured. Hence, the new equilibrium mixture will contain a lesser concentration of the product.