3.2.3 Chemical Equilibrium: Module 3: Periodic Table and Energy: Chemistry OCR A A Level

What does dynamic equilibrium mean?

It occurs when the rate of forward reaction equals the rate of reverse reaction and the concentration of reactants and products remain constant in a closed system.

Changing what factors can alter the position of equilibrium?

● Concentration of reactants or products

● Pressure

● temperature

Explain the Le Chatelier’s principle

If a system at equilibrium is disturbed, the equilibrium moves in the direction that tends to reduce the disturbance.

What effect does a catalyst have on the position of equilibrium?

No effect.

(because catalyst affects rate of forward and reverse reactions equally)

What condition affects the value of K_c?

❑ Concentration

❑ Catalyst

❑ Pressure

❑ Temperature

Temperature

What type of system is Kc relevant for?

Homogeneous systems in equilibrium.

What does K_c being greater or less than 1 suggest for the position of equilibrium?

Greater than 1 = over to the right

Less than 1 = over to the left

What effect does decreasing the temperature of an endothermic reaction have on Kc?

Kc decreases

What effect does increasing the temperature of an endothermic reaction have on Kc?

Kc increases

What effect does decreasing the temperature of an exothermic reaction have on Kc ?

Kc increases