Equilibrium

• partial pressure


  the pressure a gas exerts in a mixture of gases if it occupied the container on its own
• Total pressure


  Sum of all the partial pressures
• Mole fraction


  fraction of the total number of moles that each chemical in a reaction is responsible for
• Partial pressure equation


  Partial pressure = mole fraction x total pressure
• Mole fraction of gas equation

  mole fraction of a gas 'A' = number of moles of gas 'A' / total number of moles of gas in the mixture
• Kc


  equilibrium constant
• Kc for the equation

  aA+bB⇌cC+dD

  ([C]^c[D]^d)/([A]^a[B]^b)
• Kp


  equilibrium constant for gas-phase reactions based on partial pressures of reactants and products
• Le Chatelier's Principle


  If a change is made to a syatem in dynamic equilibrium, the position of equilibrium will change to counteract the change
• Effect of a change of temperature on Kc

  For a reaction that is exothermic in the forward direction, increasing the temperature pushes the equilibrium from right to left.

  Therefore, the value of Kc will decrease as the ratio of [products] to [reactants] decreases.

  Conversely, if the temperature is raised in an endothermic reaction, the value of Kc will increase.
• Effect of a change on temperature on Kp

  Similar to Kc, for a reaction that is exothermic in the forward direction, increasing the temperature pushes the equilibrium from right to left.

  Therefore, the value of Kp will decrease as the ratio of [products] to [reactants] decreases.

  Conversely, if the temperature is raised in an endothermic reaction, the value of Kp will increase.
• Effect of a change in pressure on Kc

  Kc is not affected as it doesnt involve gases
• Effect of a change in pressure on Kp

  Kp not affected
• Effect if a catalyst on Kp

  No affect as a catalyst increases the rate of the forwards and reverse reaction at the same rate