Students should be able to:
4.3a define the terms partial pressure and
concentration
4.3b deduce expressions for the equilibrium constants
Kc and Kp from given equations and calculate their numerical values with units, given suitable data
· expressions for Kc
should involve ‘[ ]’ implying the concentration term mol dm-3. Units
should be given for numerical values of K; if there are no units this should be explicitly
stated
· expressions for
Kp should not include the use of square brackets, since these have
specific meaning for Kc.
· students are not expected to be able to justify the fact that for heterogeneous equilibria
the activity of a solid is taken to be unity. No knowledge of solubility products will be
expected
4.3c recall that expressions for Kp and Kc for heterogeneous equilibria do not include values for solid and liquid phases
4.3d recall that the presence of a catalyst does not affect the position of equilibrium
4.3e determine the equilibrium partial pressures in a simple binary gaseous dissociation (eg that of dinitrogen tetroxide) given the value of Kp
4.3f understand that changes in temperature result in a change in the value of
Kc and Kp and that the position of equilibrum will change with change in temperature.
· students will be expected to use the expressions for
Kc and Kp to perform calculations
but they will not be expected to perform calculations that require the solution of
quadratic equations.