Chemistry SL Paper 2, May 2026

(i) The first step is the catalytic oxidation of ammonia gas to nitrogen monoxide. $\ce{4NH3(g) + 5O2(g) -> 4NO(g) + 6H2O(g)}$ Determine the volume, in dm$^3$, of nitrogen monoxide produced from 20.0 g of ammonia, at STP, using section 2 of the data booklet.…

The second step converts nitrogen monoxide to nitrogen dioxide. $\ce{2NO(g) + O2(g) <=> 2NO2(g)}$ $\Delta H^\ominus = -114\ \mathrm{kJ\,mol^{-1}}$ (i) Identify the oxidation state of nitrogen in $\ce{NO}$ and in $\ce{NO2}$. (ii) State the equilibrium constant…

The final step can be summarized as: $\ce{3NO2(g) + H2O(l) -> 2HNO3(aq) + NO(g)}$ $\Delta H^\ominus = -138\ \mathrm{kJ\,mol^{-1}}$ Describe the types of bonding found in the concentrated aqueous nitric acid product.

Nitric acid, $\ce{HNO3}$, is strong, while nitrous acid, $\ce{HNO2}$, is weak. (i) Outline the difference between a strong and a weak acid. (ii) Deduce the Lewis formula and the molecular geometry for the nitrite ion, $\ce{NO2-}$.

Many rechargeable batteries use an alkaline electrolyte. In the nickel-cadmium cell, cadmium, $\ce{Cd}$, is the anode. $\ce{Cd(OH)2(s) + 2e- -> Cd(s) + 2OH-(aq)}$ $\ce{NiO(OH)(s) + H2O(l) + e- -> Ni(OH)2(s) + OH-(aq)}$ Deduce the overall reaction for the cell.

Energy can also be produced by a hydrogen-oxygen fuel cell with an acidic electrolyte. (i) Deduce the half-equations for the electrode reactions in this fuel cell. (ii) Hydrogen produces a line emission spectrum with several lines in the visible region.…

(i) State the number of protons, electrons and neutrons in $\ce{^{85}Rb+}$. (ii) State the full electron configuration for $\ce{^{85}Rb+}$. (iii) The relative atomic mass, $A_r$, of Rb is 85.47. Isotope Mass Percent abundance $\ce{^{x}Rb}$ 72.17 %…

(i) Explain why Rb has a lower first ionization energy than strontium, Sr. (ii) Outline why Rb has a lower electronegativity than potassium, K.

(i) Write the equation for the reaction of Rb with water, $\ce{H2O}$, including state symbols. (ii) Describe the type of bonding in $\ce{Rb}$ and in $\ce{H2O}$, and explain how the valence electrons in each produce that type of bond.

(i) Determine the enthalpy of combustion of pentane, in kJ mol$^{-1}$, using table 12 in the data booklet. $\ce{C5H12(g) + 8O2(g) -> 5CO2(g) + 6H2O(g)}$ (ii) Calculate the mass, in g, of carbon dioxide, $\ce{CO2}$, produced when 45.0 g of pentane react with…

Pentane reacts with bromine, $\ce{Br2}$, to form 2-bromopentane. (i) Explain, using equations, the initiation step and two propagation steps for this reaction. (ii) State one termination step for this reaction.

Pentan-2-ol can form by reacting pent-1-ene with water in the presence of an acid catalyst. $\ce{CH2=CHCH2CH2CH3(g) + H2O(l) -> CH3CH(OH)CH2CH2CH3(aq)}$ $\Delta H^\ominus = -84\ \mathrm{kJ\,mol^{-1}}$ (i) Explain why increasing the temperature would increase…

Pentan-2-ol will react with acidified potassium dichromate, $\ce{K2Cr2O7}$, which is an oxidizing agent. State the name of the product of this reaction.

Calculate the pH of a 0.125 mol dm$^{-3}$ solution of sodium hydroxide.

A sample of the sodium hydroxide solution is gradually added to 25.0 cm$^3$ of an aqueous solution of an unknown organic acid, producing the following pH curve. Calculate the concentration of the unknown organic acid.