Chemistry - Equilibrium

Equilibrium

A state of chemical dynamic balance in a reversible reaction where the rate of the forwards reaction is equal to the rate of the reverse reaction.

When conc., temp. and pressure stay the same, the forward and backwards reactions constantly occur, but the rate stays equal, causing the reaction to never end, unless there is an external change in conc., temp. or pressure – when it will reach completion.

Pressure (increase/decrease)

If pressure is increased it will favour the side with lesser mols due to the lack of volume in closed system and naturally, will take less space in reaction

If pressure of reaction is decreased, it will favour the side with more mols due to the increase in voume in the closed system and naturally, it will take more space in the reaction.

(only applies to gaseous reaction)

Concentration (increase/decrease)

If concentration of reactants is increased, then it will favour the forwards reaction to work towards balancing the products side. If concentration of reactants is decreased then it will favour the backwards reaction for it is working to replace the concentration levels.

If concentration of products is increased, then it will favour the reverse reaction to work towards balancing the reactants side. If concentration of products is decreased then it will favour the forwards reaction for it is working to replace the concentration levels.

Temperature (increase/decrease)

If heat is added:

The endothermic direction is favored, because the system absorbs the extra heat to reduce the stress.

Equilibrium will shift in the endothermic direction.

If heat is removed:

The exothermic direction is favored, because the system releases heat to make up for the loss.

Equilibrium will shift in the exothermic direction.

LCP

If a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium moves to counteract the change.