Which of the following equilibria is unaffected by a pressure change?

  • A 2NaCI(s) ↔ 2Na (I) + CI2(g)
  • B H 2(g) + I2(g) ↔ 2HI(g)
  • C 2O3(g) ↔ 3O2(g)
  • D 2NO2(g) ↔ N2O4(g)
jamb 1991chemistry

The correct answer is B. H 2(g) + I2(g) ↔ 2HI(g)

The equilibrium concentrations of the products and reactants do not directly depend on the total pressure of the system. They may depend on the partial pressures of the products and reactants, but if the number of moles of gaseous reactants is equal to the number of moles of gaseous products, pressure has no effect on equilibrium.

Previous question Next question