Chemistry HL Paper 2, May 2025, TZ1

Tin and iodine are elements, whereas tin(IV) iodide is a compound. Describe, with reference to these three substances, how an element differs from a compound.

Outline why solid tin(IV) iodide is classified as a polar covalent compound. Use sections 9 and 17 of the data booklet.

Contrast tin and tin(IV) iodide in terms of one physical property.

Calculate the wavelength, in m, of the limit of convergence in the line emission spectrum of tin. Use sections 1, 2 and 9 of the data booklet.

Deduce the electron configuration of the $\ce{Fe^3+}$ ion.

When potassium thiocyanate solution is added to a pale yellow solution containing iron(III) ions, the following equilibrium is established. $\ce{[Fe(H2O)6]^3+(aq) + SCN^-(aq) <=> [Fe(SCN)(H2O)5]^2+(aq) + H2O(l)}$ $\ce{[Fe(H2O)6]^3+(aq)}$ is pale yellow and…

State, in terms of equilibrium concentrations, the expression for $K$, the equilibrium constant of this reaction.

By the time equilibrium was reached, the vessel held 1.7 mol of $\ce{H2(g)}$. Calculate the equilibrium amounts, in mol, of the three remaining gases, then use them to calculate $K$.

In a molten carbonate fuel cell the mixture of hydrogen and carbon dioxide from the reaction is fed to the anode, while a mixture of oxygen and carbon dioxide is fed to the cathode. Carbonate ions, $\ce{CO3^2-}$, move through the molten electrolyte from the…

Suggest why a molten carbonate fuel cell running on this gas mixture is considered to have a low environmental impact.

(i) Write a balanced equation, with state symbols, for this reaction. (ii) Deduce which of the two reactants runs out first, that is, which one limits the reaction. Use sections 1, 4 and 7 of the data booklet. (iii) Calculate the volume, in $\mathrm{dm^3}$,…

The rate of the reaction can be followed by measuring the volume of carbon dioxide collected as time passes. The graph shows the results obtained at 20 °C. (i) Sketch, on the same axes, the curve you would expect if the experiment were repeated with the acid…

Magnesium carbonate and magnesium chloride are ionic compounds. (i) The Born-Haber cycle for magnesium chloride, $\ce{MgCl2}$, is shown with three boxes left empty. Annotate the cycle by writing the name of the process, or the formulas of the species present…

Sketch, on the axes provided, the pH curve for this titration.

A buffer solution can be prepared by mixing $\ce{NH3(aq)}$ with $\ce{HCl(aq)}$. (i) Describe how the two solutions should be combined so that the buffer obtained is as effective as possible. (ii) Write equations to show how this buffer solution responds to the…

In the first step, manganese(III) ions formed from the manganate(VII) are complexed by ethanedioate ions. $\ce{[Mn(H2O)6]^3+(aq) + 2C2O4^2-(aq) -> [Mn(C2O4)2(H2O)2]^-(aq) + 4H2O(l)}$ (i) Deduce the oxidation state of carbon in $\ce{[Mn(C2O4)2(H2O)2]^-}$. (ii)…

Both ionic and covalent bonding are present in sodium ethanedioate, $\ce{Na2C2O4}$. (i) Describe both types of chemical bonding present in this compound. Ionic bonding: Covalent bonding: (ii) Deduce a Lewis formula of the ethanedioate ion, $\ce{C2O4^2-}$.…

When 3.71 g of Z was burned completely in excess oxygen, 8.81 g of carbon dioxide and 4.51 g of water were collected. Determine the empirical formula of Z. Use sections 1 and 7 of the data booklet.

A second sample of Z was converted completely into vapour at a known temperature and pressure. (i) 0.148 g of the vapour occupied 63.7 $\mathrm{cm^3}$ at 110 °C and a pressure of $1.00 \times 10^{5}$ Pa. Calculate the amount, in mol, of Z in this sample. Use…

The displayed formula below shows part of the chain of an addition polymer. (i) Deduce the structural formula of the monomer used to build this polymer. (ii) Describe one chemical property responsible for this type of polymer being a useful material.

The compound X shown below occurs naturally in cocoa and coffee and is used as a flavouring agent. (i) State the name of the functional group found in compound X. (ii) Deduce the IUPAC name of X. (iii) Deduce how many signals the $\ce{^1H}$ NMR spectrum of X…

But-2-ene and other alkenes serve as starting materials for a wide range of compounds. (i) Predict the product formed when but-2-ene reacts with bromine. (ii) Describe how this reaction proceeds at the mechanistic level, drawing curly arrows for each…

When 1-bromopropane is warmed with aqueous sodium hydroxide, $\ce{NaOH(aq)}$, propan-1-ol is formed. (i) State the name given to this reaction's mechanism. (ii) Draw the structure of the transition state that occurs during this mechanism. (iii) Deduce the rate…

Several stereoisomers exist among the dichloroalkenes of molecular formula $\ce{C4H6Cl2}$. (i) Draw the structural formula of cis-2,3-dichlorobut-2-ene. (ii) Outline why the cis-isomer of 2,3-dichlorobut-2-ene is polar, whereas the trans-isomer is not. (iii)…

trans-But-2-ene reacts with hydrogen in the presence of a nickel catalyst to form butane. $\ce{C4H8(g) + H2(g) -> C4H10(g)}$ (i) Calculate, in kJ, the enthalpy change of this reaction from the bond enthalpies in section 12 of the data booklet. (ii) Calculate,…