Kp

• total pressure - sum of all pressures of individual gases
• partial pressure - the pressure of each individual gas
• • the partial pressure of gas is calculated using mole fractions
  • a mole fraction is the proportion of a gas in a gas mixture
• mole fraction = moles of desired gas/total moles of gas in the mixture
• partial pressure = mole fraction of gas x total pressure
• mole fraction and partial pressure calc:

  • find out the initial moles
  • calculate change in moles
  • calculate moles at equilibrium
• • Kp is the equilibrium constant for a reaction involving gases
  • partial pressures are used instead of concentrations
• Kp = pp of products/reactants
• Kp equation:

  • A + B --> C + D

  A) C

  B) c

  C) D

  D) d

  E) A

  F) a

  G) B

  H) b

  
• effect of temperature on Kp:

  • if temperature change causes equilibrium to shift to the right, Kp will increase
  • if temperature change causes equilibrium to shift to the left, Kp will decrease
• using the Kp expression:

  • if the partial pressure of the products increases, Kp increases
  • if the partial pressure of the reactants increases, Kp decreases
• changing pressure and catalysts have no effect on the value of Kp