Topic 5

Question 1

In the decomposition of hydrogen iodide to form hydrogen and iodine, how would the appearance of the contents of a tube change as it was cooled to room temperature?

[2 marks]

Answer 1

The purple gas would turn colourless and then a grey solid would be formed

Question 2

In the decomposition of hydrogen iodide to form hydrogen and iodine, how could you show that an equilibrium had been established?

[2 marks]

Answer 2

Heat for different lengths of time

Measure the concentration of a reactant or product of two tubes which should be the same

Question 3

Write an expression for the equilibrium constant Kc at 700k, for the decomposition of hydrogen iodide to form hydrogen and iodine,

Answer 3

K = [H2][I2] / [HI]^2