Equilibria Answers

Kc Questions

  1. The system is closed; the forward and reverse reactions are taking place at the same rate; the concentrations of reactants and products are not changing
  2. Units
  3. 0.042 moldm-3
  4. 1.33 x 10-3 moldm-3
  5. 56.3
  6. 0.2 moldm-3
  7. 6.6 mol-2dm6
  8. 1010 mol-1dm3
  9. 3.2 x 10-4 moldm-3
  10. 46.3 mol-2dm6
  11. 4.12
  12. 12 moldm-3

Kp Questions

  1. Units
  2. 2.96 kPa
  3. 0.218 kPa
  4. 56.2
  5. 133.3 kPa
  6. 0.0607 MPa-2
  7. 0.86 kPa-1
  8. 4.2 kPa
  9. 4.03 x 10-5 kPa-2
  10. 80 kPa

Changing the position of equilibrium

  1. a) equilibrium moves to the right to replace lost water so [Cl2] increases and [HCl] decreases
  • b) equilibrium moves to the right to remove added oxygen so [Cl2] increases and [HCl] decreases
    c) pressure is increased so equilibrium moves to the right in direction of fewer moles to reduce pressure so [Cl2] increases and [HCl] decreases
    d) equilibrium moves to left in endothermic direction to reduce the temperature so [Cl2] decreases and [HCl] increases.
    e) equilibrium does not move as forward and reverse reactions are getting faster by the same amount so [Cl2] and [HCl] remain the same

 

  1. a) low temperature, as this will favour the exothermic direction which is the forward direction high pressure, as this will favour the direction decreasing the gas moles which is the forward direction
  • b) high temperature, as this will favour the endothermic direction which is the forward direction low pressure, as this will favour the direction increasing the gas moles which is the forward direction
  • c) low temperature, as this will favour the exothermic direction which is the forward direction any pressure, as there is no change un the number of gas moles
  • d) any temperature, as there is no exothermic or endothermic direction any pressure, as there is no change in the number of moles
  1. a) yield is poor at high temperatures
  • b) reaction is slow at low temperatures
  • c) expensive equipment is needed for high pressures
  • d) yield is poor at low pressures, the reaction is slow at low pressures
  • e) catalyst increases the rate of the reaction and reduces costs by allowing a lower temperature to be used