Chemical equilibrium — Question 8

QUESTION 8 (7 marks)

Two experiments were conducted to investigate the effect of temperature on the equilibrium formed during the decomposition of hydrogen iodide (HI).

$\mathrm{2HI(g)}\rightleftharpoons\mathrm{H}_{2}\mathrm{(g)}+\mathrm{I}_{2}\text{(g) ∆}\mathrm{H}\,=\,+\text{53.6 kJ mol}^{-1}$

Experiment	Initial concentration (mol L-1)			Equilibrium concentration (mol L-1)			Kc
	[HI]	[H2]	[I2]	[HI]	[H2]	[I2]
1	0.08	0.00	0.00		0.01		2.78 × 10−2
2	0.00	0.06	0.06	0.06	0.03	0.03

(a) Determine the concentration of HI(g) and I₂(g) at equilibrium for experiment 1.

[2 marks]

[HI]:

[I₂]:

(b) Calculate the equilibrium constant (K_c) for experiment 2. Show your working.

[2 marks]

(c) Determine which experiment was conducted at a higher temperature. Explain your reasoning.

[3 marks]