1.10 Equilibrium Constant Kp

• what is the gas equilibrium constant (Kp)?

  equilibrium constant for a reversible reaction where some or all of the reactants and products are gases
• how do you express Kp?

  Kp = products/ reactants

  
• how do you calculate mole fraction?

  mole fraction of a gas = number of moles of a gas / total number of moles of gas in the mixture
• how do you calculate partial pressure of a gas?

  mole fraction of a gas x total pressure of a mixture
• what is Le Chatelier's principle?

  if a reaction at equilibrium is subjected to a change in temperature, concentration or pressure, the position of equilibrium will shift to oppose the change
• what happens to equilibrium if temperature is decreased?

  equilibrium will shift in the direction of the exothermic reaction (exothermic gives out heat) to increase the temperature to oppose change
• what happens to equilibrium if temperature is increased?

  equilibrium will shift in the direction of the endothermic reaction (endothermic will take in heat) so will decrease the temperature to oppose the change
• what affect does changing temperature to shift equilibrium to the right have on Kp?

  will increase Kp as the partial pressure of the products will increase
• what affect does changing temperature to shift equilibrium to the left have on Kp?

  will decrease Kp as the partial pressure of the products will decrease
• what affect does changing pressure have on Kp?

  changing pressure has an equal and opposite effect therefore changing the pressure has no effect on the value of Kp
• what affect does adding a catalyst have on Kp?

  adding a catalyst increases the rate of the forward and backward reactions, by the same amount and therefore equilibrium will be reached quicker but will remain unchanged and as a result the partial pressures of both the reactants and products will remain the same. Therefore adding a catalyst has no effect on Kp