Calculations involving equilibrium systems use
    Qp = p(C)cp(D)d
    p(A)ap(B)b
  • the fact that, for a system at equilibrium at a particular temperature, the reaction quotient Q is equal to the equilibrium constant K .

    The Q given is for reaction aA + bB cC + dD, where A, B, C and D are all gases. Q where amounts are expressed in partial pressures is given the symbol Qp.

    Each partial pressure substituted into Q when calculating K must be divided by the standard state pressure (100 kPa).

  • the stoichiometry of the reaction occurring to reach equilibrium if the system is not initially at equilibrium.
In both problems in this set initial partial pressures of all gases appearing in Q are known.

In problem 1 the equilibrium pressure of one gas is also known, and Kp is calculated.
In problem 2 Kp is known and the equilibrium pressure of one component gas is calculated.
Dr Sheila Woodgate
© The University of Auckland 2002