Homogeneous and heterogeneous catalysts: past paper questions

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• Question 15May/June 2026, paper 12Multiple choice1 markHas a diagram

  The diagram shows a Boltzmann distribution of molecular energies for a gaseous mixture. The distribution has a peak, labelled P. What happens when an effective catalyst is added to the mixture?

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• Question 14Oct/Nov 2025, paper 11Multiple choice1 mark

  Photochromic glass, used for sunglasses, darkens when exposed to bright light and becomes more transparent again when the light is less bright. The darkness of the glass is due to the presence of silver atoms. The following reactions are involved.

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• Question 16Oct/Nov 2024, paper 12Multiple choice1 markHas a diagram

  The Boltzmann distribution for a mixture of gases capable of reaction is shown. The two curves represent the mixture of gases at ${25}^{\circ }\text{C}$ and at ${35}^{\circ }\text{C}$. The activation energies for the catalysed and uncatalysed reactions are shown.

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• Question 16Oct/Nov 2023, paper 12Multiple choice1 markHas a diagram

  The decomposition of hydrogen peroxide in the presence of ${\text{MnO}}_2$ produces water and oxygen gas.

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• Question 18May/June 2026, paper 12Multiple choice1 mark

  Two procedures are described. 1 Sulfur is burned in an excess of oxygen then NO is added to the product mixture. 2 Sulfur is burned in an excess of oxygen then ${\text{NO}}_2$ is added to the product mixture.

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• Question 15Oct/Nov 2025, paper 11Multiple choice1 mark

  The reversible reaction between methanol and ethanoic acid liquids is catalysed by adding a small volume of concentrated sulfuric acid. Two statements about this reaction are listed. 1 The sulfuric acid is a homogeneous catalyst.

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• Question 15May/June 2024, paper 11Multiple choice1 markHas a diagram

  The Boltzmann distribution for the hydrogenation of an alkene at a particular temperature in the absence of a catalyst is shown. Which row correctly describes the effects of adding a nickel catalyst to the reaction vessel?

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• Question 16May/June 2023, paper 12Multiple choice1 markHas a diagram

  The diagram shows the Boltzmann distribution of energies in a gas. The gas can take part in a reaction with an activation energy, $E_{\text{a}}$. The gas is maintained at a constant temperature.

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• Question 15May/June 2026, paper 13Multiple choice1 markHas a diagram

  The graph shows a Boltzmann distribution for a sample of reacting gas at a temperature $T\text{ K}$. The activation energy, $E_{\text{A}}$, for the reaction is marked. Point Q is the point of intercept of the curve with the value of the activation energy, $E_{\text{A}}$.

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• Question 13Oct/Nov 2025, paper 12Multiple choice1 mark

  In the Contact process, sulfur dioxide and oxygen react to form sulfur trioxide. In the Haber process, nitrogen and hydrogen react to form ammonia. Which statement about these processes is correct?

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• Question 23May/June 2024, paper 11Multiple choice1 mark

  Nitrogen dioxide is a gas that contributes to air pollution. It is produced in internal combustion engines. Which statement is correct?

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• Question 15May/June 2024, paper 12Multiple choice1 markHas a diagram

  Gas Q decomposes slowly at room temperature. $$\text{Q(g)}\to \text{X(g)}+\text{Z(g)}$$ The Boltzmann distribution curve for gas Q at room temperature is shown. Which change occurs when a catalyst is added to gas Q?

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• Question 3May/June 2025, paper 11Multiple choice1 markHas a diagram

  In the diagram, curve X was obtained by measuring the volume of oxygen produced during the decomposition of $100{\text{ cm}}^3$ of $1.0\text{ mol}{\text{dm}}^{-3}$ hydrogen peroxide. A catalyst of manganese(IV) oxide was used.

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• Question 8May/June 2025, paper 12Multiple choice1 markHas a diagram

  In the Haber process, the reaction between the two gaseous reactants requires the use of a catalyst that contains a transition element. What is the metal and in which mole ratio do the gases react?

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• Question 7May/June 2025, paper 13Multiple choice1 markHas a diagram

  The gaseous compound Z decomposes on heating. In the diagram, Boltzmann distributions for Z at two different temperatures, P and Q, are shown. The lines X and Y indicate activation energies for the decomposition of Z with and without a catalyst.

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• Question 3May/June 2025, paper 21Structured10 marksHas a diagram

  Hexene reacts with hydrogen gas to produce hexane.

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• Question 3May/June 2025, paper 23Structured7 marksHas a diagram

  Different hydrocarbon mixtures produced from fractional distillation of crude oil have different uses. State the compound that is heated with long-chain hydrocarbons to produce more useful smaller alkanes and alkenes.

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