Edexcel A-Level Chemistry AS 9.10 Predict and Justify the Qualitative Effects of Changes of Temperature Pressure and Concentration on the Position Questions

Practise Edexcel IAL Chemistry 9.10 by predicting how temperature, pressure and concentration changes shift homogeneous equilibria using Le Chatelier reasoning.

Exam points

Predict how changing temperature affects equilibrium position using the reaction enthalpy.
Predict how changing pressure affects equilibrium position from gaseous mole numbers.
Predict how changing concentration or removing a species shifts equilibrium position.

[Maximum number: 2]

Fuels

Fuels burn in oxygen to release a lot of energy.
Many hydrocarbons and alcohols are used as fuels. During complete combustion, they produce carbon dioxide and water.

Petrol contains 2,2,4-trimethylpentane, an isomer of octane, that promotes smooth combustion.

Figure for Question Edexcel A-Level Chemistry AS 9.10 Predict and Justify the Qualitative Effects of Changes of Temperature Pressure and Concentration on the Position Questions question 1 — Edexcel A-Level Chemistry AS

2,2,4-trimethylpentane

Alcohols, such as methanol and ethanol, can be used as fuels either on their own or as additives in petrol.

Ethanol can be manufactured by reacting ethene with steam.

\mathrm{C}_{2} \mathrm{H}_{4}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{~g}) \rightleftharpoons \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(\mathrm{~g}) \quad \Delta_{\mathrm{r}} H=-45 \mathrm{~kJ} \mathrm{~mol}^{-1}

This reaction is usually carried out in industry at $300^{\circ} \mathrm{C}$ and 70 atm pressure using a catalyst.

Explain the effect on the equilibrium position and the equilibrium yield of ethanol if the reaction is carried out at $300^{\circ} \mathrm{C}$ and 200 atm pressure.

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Edexcel A-Level Chemistry AS 9.10 Predict and Justify the Qualitative Effects of Changes of Temperature Pressure and Concentration on the Position Questions question 1