Mole Fraction

  • The mole fraction is a unit of concentration, defined to be equal to the number of moles of a component divided by the total number of moles of a solution
  • The mole fraction is determined for all reactants in a mixture of gases
  • g. to find the mole fraction of A (Xa):

Partial pressure

  • Partial pressure it the pressure exerted by the single gas if it were isolated
  • The total pressure is the combined total of all the partial pressures
  • To determine the partial pressure for one gas, multiply the mole fraction by the total pressure
  • g. to find the partial pressure of A (PA):
  • Units for partial pressure Pascals or atmospheres

PA = Mole Fraction of A  x Total Pressure

PA = Xa  x   P

Kp in homogeneous gaseous equilibria

    • Homogeneous Equilibria refers to all involved reactants are in the same phase
    • For Kp to function, everything must be a gas

  • Kp will always be a constant except for a change in temperature

Kp in heterogeneous equilibria

  • Heterogeneous equilibrium will involve gases in contact with solids
  • As Kp functions only with a gas, the solid is not included