Chemistry - rates and equilibrium (The rate and extent of chemical change)

reversible reaction

a reaction were the products can also form the reactants. If one direction is exothermic, the other one is always endothermic

exothermic

transfers energy to the surroundings

endothermic

takes in energy from surrounding

equilibrium

when the forward and backward reaction in a reversible reaction happen at the same rate in a sealed container

le chatelier’s principle

when a change of conditions happens to a system at equilibrium, the position of equilibrium moves to cancel out the change

If the concentration of a system at equilibrium is increased, what happens to the equilibrium?

• equilibrium shifts to opposite side of substance which has increased concentration

If the concentration of a system at equilibrium is decreased, what happens to the equilibrium?

• equilibrium shifts to the side of substance which has decreased concentration

(for gaseous reactions)
If the pressure of a system at equilibrium is increased, what happens to the equilibrium?

• the equilibrium position will shift towards the side with the smaller number of molecules

(for gaseous reactions)

If the pressure of a system at equilibrium is decreased, what happens to the equilibrium?

• the equilibrium position will shift towards the side with the larger number of molecules

If the temperature of a system at equilibrium is increased, what happens to the equilibrium?

• equilibrium shifts to the endothermic side to increase products

• the products at the exothermic side decrease

If the temperature of a system at equilibrium is decreased, what happens to the equilibrium?

• equilibrium shifts to the exothermic side to decrease products

• the products at the endothermic side increase

The equilibrium mixture is cooled.

Explain what happens to the concentration of the pink cobalt compound. [3]

• concentration increases

• because equilibrium moves to the left

• because the reverse reaction is exothermic