Chemistry SL Paper 2, November 2025, TZ3

Outline one reason why $\ce{SO2}$ is considered a pollutant.

A sample of flue gas has a volume of $2.5 \times 10^{-3}\ \mathrm{m^3}$ at 150 °C and $1.2 \times 10^5$ Pa, and contains 0.20 % $\ce{SO2}$ by volume. Using sections 1 and 2 of the data booklet, calculate the amount, in moles, of $\ce{SO2}$ present.

Sulfur dioxide can also be removed from flue gas by reaction with hydrogen peroxide, forming sulfuric acid. $\ce{SO2(g) + H2O2(aq) -> H2SO4(aq)}$ Deduce which element is reduced in this process, indicating the initial and final oxidation states. Element…

(i) In aqueous solution sulfuric acid transfers a proton to a water molecule, forming the hydroxonium ion, $\ce{H3O+}$. Annotate the structure of the hydroxonium ion to indicate the coordination bond. (ii) Write an equation for the reaction between excess…

(i) For the carbonate ion, draw its Lewis formula. (ii) Write the chemical formula of ammonium carbonate.

(i) If the reaction has a percentage yield of 80 %, calculate the mass, in g, of benzene that would be produced from 2.0 kg of cyclohexane. (ii) Calculate the atom economy for this reaction, as a percentage.

The forward reaction is endothermic, uses platinum as a catalyst, and takes place at 800 K. Sketch the reaction's energy profile both with and without the catalyst present, labelling the activation energies and $\Delta H$.

(i) Sketch the Maxwell–Boltzmann distribution curve for 298 K on the same axes as the 800 K curve. (ii) On the graph, annotate the position corresponding to the activation energy, $E_\mathrm{a}$. (iii) With reference to the graph, explain why a lower…

Hex-1-ene, $\ce{CH2=CHCH2CH2CH2CH3}$, is used to manufacture poly(hex-1-ene). (i) Complete the diagram to show the repeating unit of poly(hex-1-ene). (ii) State the type of polymerization that occurs.

A compound used to make polymers, hexanedioic acid, can be produced by a series of reactions starting from cyclohexane. (i) Deduce how reactant A is related to hex-1-ene. (ii) For the C=O functional group present in intermediate C, state its structural…

Hexanoic acid, $\ce{CH3(CH2)4COOH}$, is a weak acid. The graph shows how the pH changes during the titration of a 20.0 $\mathrm{cm^3}$ aqueous solution of hexanoic acid with aqueous sodium hydroxide. (i) Deduce an expression for the equilibrium constant, $K$,…

State what type of reaction this is.

Using curly arrows to show the movement of electron pairs, sketch the mechanism of this reaction.

Determine the standard enthalpy change of the reaction, in kJ mol⁻¹. Use section 12 of the data booklet. Ignore interactions between ions and the solvent.

Contrast the two isotopes in terms of atomic structure.

Calculate the relative atomic mass of chlorine from the sample, giving your answer to two decimal places.

(i) Deduce the condensed electron configuration of chlorine. (ii) Describe the bonding in a molecule of chlorine in terms of valence electrons. (iii) Explain why chlorine has a much lower boiling point than bromine, although both exist as simple diatomic…