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Edexcel IGCSE Chemistry 3.22C equilibrium yield changes

Edexcel IGCSE Chemistry 3.22C equilibrium yield changes
Edexcel IGCSE Chemistry syllabusChemistry 4CH1First assessment 2019

Practise equilibrium-yield questions by comparing gas moles, using endothermic or exothermic directions and reading yield graphs.

How this is tested

  • Predict pressure effects by comparing gas moles on each side of the equation.
  • Explain temperature effects using the endothermic and exothermic directions.
  • Interpret yield graphs to decide whether the forward reaction is exothermic.

Question 6

[Maximum number: 4]

Hydrogen reacts with iodine vapour to form hydrogen iodide, HI
This is the equation for the reaction.

H2( g)+I2( g)⇌2HI( g)ΔH=+26 kJ/mol\mathrm{H}_{2}(\mathrm{~g})+\mathrm{I}_{2}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{HI}(\mathrm{~g}) \quad \Delta H=+26 \mathrm{~kJ} / \mathrm{mol}

Question 6(b)

(a)

In a sealed container at equilibrium, the reaction conditions are 500∘C500^{\circ} \mathrm{C} and 2 atm .

[ 4 ]

Question 6(b)(i)

(i)

The temperature of the reaction mixture is increased to 600∘C600^{\circ} \mathrm{C}, but the pressure is kept at 2 atm .

Explain the effect, if any, on the yield of hydrogen iodide at equilibrium.

[ 2 ]

Question 6(b)(ii)

(ii)

The pressure of the reaction mixture is decreased to 1 atm but the temperature is kept at 500∘C500^{\circ} \mathrm{C}.

Explain the effect, if any, on the yield of hydrogen iodide at equilibrium.

[ 2 ]