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Edexcel IAL Chemistry 9.10 Factors affecting equilibrium position

Identify the endothermic direction or side with fewer gas moles, then treat rate separately from equilibrium yield and explain removal or addition of a species.

Syllabus
First assessment 2019
Course
Chemistry YCH11
Level
AS

Exam points

  • Predict temperature effects from the endothermic direction while separating rate from yield.
  • Predict pressure effects from gaseous mole numbers and distinguish rate and equilibrium shifts.
  • Explain concentration changes through consumption, removal or addition of a named species.

9.11—Evaluate data to explain the necessity, for many industrial processes, to reach a compromise between the yield and the rate question 1

[Maximum number: 5]

The Sabatier process uses carbon dioxide and hydrogen to produce methane and water.

CO2( g)+4H2( g)⇌CH4( g)+2H2O( g)ΔrH=−165 kJ mol−1\mathrm{CO}_{2}(\mathrm{~g})+4 \mathrm{H}_{2}(\mathrm{~g}) \rightleftharpoons \mathrm{CH}_{4}(\mathrm{~g})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{~g}) \quad \Delta_{\mathrm{r}} H=-165 \mathrm{~kJ} \mathrm{~mol}^{-1}

The process is carried out at a temperature of 400∘C400^{\circ} \mathrm{C} and a pressure of 30 atm , in the presence of a nickel catalyst.

Discuss the advantages and disadvantages of using such high temperatures and pressures in the process.

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