Rates, equilibrium and pH

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Question 43

This question is about chemical equilibria and industrial processes.

Methanol is manufactured industrially by the reaction of carbon monoxide with hydrogen. The equilibrium is shown below:

\text{CO}(\text{g}) + 2\text{H}_2(\text{g}) \rightleftharpoons \text{CH}_3\text{OH}(\text{g}) \quad \Delta H = -91\text{ kJ mol}^{-1} \quad \text{Equilibrium 20.1}

$CO(g)1.50\text{ mol }\text{CO}(\text{g})$ is mixed with $H2(g)3.00\text{ mol }\text{H}_2(\text{g})$ in a $dm32.00\text{ dm}^3$ container. The mixture is heated and allowed to reach equilibrium in the presence of a copper-based catalyst. The equilibrium mixture contains $CH3OH0.60\text{ mol }\text{CH}_3\text{OH}$ .

Determine the equilibrium constant $KcK_{\text{c}}$ for Equilibrium 20.1 (including units), and explain why the operational conditions (temperature and pressure) used in industrial synthesis may differ from those required for a maximum equilibrium yield of methanol.

[6]

Tin metal can be extracted from its oxide, cassiterite ( $SnO2\text{SnO}_2$ ), by reduction with carbon monoxide at high temperature as shown in Equilibrium 20.2:

\text{SnO}_2(\text{s}) + 2\text{CO}(\text{g}) \rightleftharpoons \text{Sn}(\text{s}) + 2\text{CO}_2(\text{g}) \quad \text{Equilibrium 20.2}

When the temperature is increased, the value of $KpK_{\text{p}}$ increases. Determine whether the forward reaction is exothermic or endothermic. Explain your answer.

[2]

Two students are discussing the effect of pressure on the equilibrium position of Equilibrium 20.2.

Student A says: "Since there are 3 total moles of reactants and 3 total moles of products, increasing the pressure will have no effect on the equilibrium position."
Student B says: "We must only count the moles of gaseous species. Since there are 2 moles of gas on both sides, changing the pressure has no effect on the equilibrium position."

Determine which student has the correct reasoning. Justify your answer.

[3]

Rates, equilibrium and pH

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Question 43

This question is about chemical equilibria and industrial processes.

Methanol is manufactured industrially by the reaction of carbon monoxide with hydrogen. The equilibrium is shown below:

\text{CO}(\text{g}) + 2\text{H}_2(\text{g}) \rightleftharpoons \text{CH}_3\text{OH}(\text{g}) \quad \Delta H = -91\text{ kJ mol}^{-1} \quad \text{Equilibrium 20.1}

[6]

Tin metal can be extracted from its oxide, cassiterite ( $SnO2\text{SnO}_2$ ), by reduction with carbon monoxide at high temperature as shown in Equilibrium 20.2:

\text{SnO}_2(\text{s}) + 2\text{CO}(\text{g}) \rightleftharpoons \text{Sn}(\text{s}) + 2\text{CO}_2(\text{g}) \quad \text{Equilibrium 20.2}

When the temperature is increased, the value of $KpK_{\text{p}}$ increases. Determine whether the forward reaction is exothermic or endothermic. Explain your answer.

[2]

Two students are discussing the effect of pressure on the equilibrium position of Equilibrium 20.2.

Student A says: "Since there are 3 total moles of reactants and 3 total moles of products, increasing the pressure will have no effect on the equilibrium position."
Student B says: "We must only count the moles of gaseous species. Since there are 2 moles of gas on both sides, changing the pressure has no effect on the equilibrium position."

Determine which student has the correct reasoning. Justify your answer.

[3]

Rates, equilibrium and pH

Question 43

Rates, equilibrium and pH Questions

Rates, equilibrium and pH

Question 43

Rates, equilibrium and pH Questions