The Effect of Changing Concentration Flashcards

All 6 cards in this deck

What happens to a system at equilibrium if the concentration of a reactant is increased?

Equilibrium shifts to the right — more products are formed until equilibrium is reached again.

What happens to a system at equilibrium if the concentration of a product is decreased?

Equilibrium shifts to the right — more reactants react until equilibrium is reached again.

What happens to a system at equilibrium if the concentration of a product is increased?

Equilibrium shifts to the left — more reactants are formed until equilibrium is reached again.

True or false? Removing a product from an equilibrium mixture increases the amount of reactant.

False. The equilibrium shifts right to replace the product, so more reactant is used up.

What are the steps to predict the colour change when more of a reactant is added to a coloured equilibrium mixture?

e.g. adding thiocyanate ions to $\mathrm{Fe^{3+}} + \mathrm{SCN^-} \rightleftharpoons \mathrm{FeSCN^{2+}}$ (red)

1. Note the change: concentration of a reactant (SCN$^-$) is increased.
2. Equilibrium moves right to reduce that increase.
3. Concentration of the product rises: the mixture becomes more red.

True or false? Once equilibrium is reached, adding more reactant has no effect because the rates are already equal.

False. The system is no longer at equilibrium and shifts right until a new equilibrium is reached.