Equilibrium

What does equilibrium mean?

• reversible reaction is carried out in a closed container so reactants and products cannot escape

• Forward and reverse reaction happen at exact Same speed

What is the Le Chatelier principle?

Le Chatelier's Principle

states that if a system at equilibrium is disturbed by a change in concentration, temperature, or pressure, the system will shift to partially offset the change and establish a new balance

What happens at equilibrium when the concentration changes?

1) increase of concentration: it moves the eq position to the other side

2) decrease of c: moves it to the same side (stays)

What happens with pressure in equilibrium?

1) increasing pressure: shifts eq position to the side with the fewest gas molecules (ONLY GAS)

2) decreasing pressure: shifts to side with the most gas molecules

Only when reactions involve gases!

What happens with the temperature in equilibrium?

1) Place heat:

• Delta H = + (endothermic) —> heat at reactant

• Delta H = - (exothermic) —> heat at product

2) Shift rule:

• temp increase = switches sides

• temp decrease = stays at same side

What happens when a catalyst is added to a reversible reaction?

• catalysts have no effect on the position of the equilibrium

• Make equilibrium reached faster