Le Chatelier's principle: If the external condition is changed, the equilibrium will shift to oppose this change. What are these external conditions that can be changed? Temperature, pressure and concentration Temperature: If you increase the temperature, the equilibrium will shift in the direction of the endothermic reaction to reduce the temperature by absorbing heatConcentration: An increase in concentration will shift equilibrium to the opposite side so more of that reaction is taking place to oppose the increase in concentrationPressure: An increase in pressure will cause the equilibrium to shift to the side with the lowest moles of gas to oppose the increase in pressure. Be aware to look out for state symbols! Catalyst: has no effect on equilibria.