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3 marksPrinciples of Chemical Equilibrium

CAPE Chemistry Unit 1 · 2012 · Paper 2 · Question 5(d)

Phosphorus(V) chloride, PCl5, decomposes at 250 °C and forms an equilibrium mixture represented by the equation PCl5(g) ⇌ PCl3(g) + Cl2(g). One equilibrium mixture at this temperature contains PCl5 and PCl3 at concentrations of 0.20 mol dm⁻³ and 0.010 mol dm⁻³ respectively. Given Kc at 250 °C = 0.19 mol dm⁻³.

Calculate the concentration of Cl2 in the mixture.

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Other parts of this question

  1. 5(a)(i)Copy and complete Table 3 to show the type of equilibrium for the selected equilibrium systems.[3 marks]
  2. 5(a)(ii)State TWO characteristics of the equilibrium represented by System 1 in Table 3.[2 marks]
  3. 5(b)(i)Write the expression for the equilibrium constant.[1 mark]
  4. 5(b)(ii)What deduction can be made when the equilibrium constant is much greater than 1?[1 mark]
  5. 5(c)(i)Explain why the white precipitate, BiOCl, disappears on the addition of aqueous HCl to the equilibrium mixture.[2 marks]
  6. 5(c)(ii)Explain what would be observed if a large volume of water was added to the equilibrium mixture.[3 marks]

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