Chemistry SL Paper 2, November 2023, TZ1

Chemia IBPaper 2, listopad 2023, TZ1wzorowane1 pktotwartełatwe (szac.)

Zadanie 1a

Propanoic acid, CH₃CH₂COOH, is the next member of the series. Outline two characteristics that make ethanoic acid and propanoic acid members of the same homologous series.

Chemia IBPaper 2, listopad 2023, TZ1wzorowane1 pktotwarteśrednie (szac.)

Zadanie 1b

Draw a Lewis (electron dot) formula for a molecule of ethanoic acid, showing every bonding and non-bonding electron pair.

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Zadanie 1c

Calculate the percentage by mass of carbon in ethanoic acid.

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Zadanie 1d

Ethanoic acid and propanone, CH₃COCH₃, each contain a C=O group, and their molar masses are close. (i) Considering the strongest intermolecular forces in each liquid, explain why propanone boils at a much lower temperature than ethanoic acid.…

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Zadanie 2a

Hydrogen iodide is an intermediate in some thermochemical cycles that are being researched as a way of obtaining hydrogen from water without using fossil fuels. Explain why there is great interest in producing hydrogen in this way.

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Zadanie 2b

State the expression for the equilibrium constant, K_c, of this reaction.

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Zadanie 2c

Approximate enthalpy changes of reactions can be found from bond enthalpies. (i) Determine the enthalpy change, ΔH^⊖, of this reaction, in kJ mol⁻¹, using section 12 of the data booklet. (ii) Each bond enthalpy is uncertain by 0.1…

Chemia IBPaper 2, listopad 2023, TZ1wzorowane1 pktotwarteśrednie (szac.)

Zadanie 2d

Deduce, using your answer to 2c(i), how the value of K_c changes when the temperature of the equilibrium mixture is increased.

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Zadanie 2e

The reaction is usually carried out at a high temperature in the presence of a catalyst. (i) On the axes provided, sketch the energy profile of the reaction for the uncatalysed and for the catalysed pathway, and show ΔH and the activation energies.…

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Chemia IBPaper 2, listopad 2023, TZ1wzorowane1 pktotwartełatwe (szac.)

Zadanie 2f

Determine the oxidation state of iodine in the iodate ion, IO₃⁻.

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Zadanie 3a

State the name of the reagent that is heated with ethanoic acid to form this ester.

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Zadanie 3b

A student obtained 2.58 g of the ester from 3.00 g of ethanoic acid and an excess of the second reagent. Determine the percentage yield of the ester.

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Zadanie 3d

State the homologous series to which CH₃COOCH₃ belongs.

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Zadanie 3e

Draw the full structural formula of the carboxylic acid that is a structural isomer of CH₃COOCH₃.

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Zadanie 3f

State the name of a compound that forms the carboxylic acid isomer from 3e when it is heated under reflux with an excess of an oxidizing agent.

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Zadanie 4a

The enthalpy changes of two combustion reactions are $\ce{COS(g) + 3/2 O2(g) -> CO2(g) + SO2(g)}$   ΔH^⊖ = −549 kJ mol⁻¹ $\ce{H2S(g) + 3/2 O2(g) -> H2O(g) + SO2(g)}$   ΔH^⊖ = −518 kJ mol⁻¹ Use…

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Zadanie 4b

Deduce the molecular geometry of COS and of H₂S, and state why the two geometries differ.

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Zadanie 4c

Naturally occurring sulfur is a mixture of several isotopes. A sample was enriched in $\ce{^{34}_{16}S}$, giving the following composition: (i) Calculate the relative atomic mass of the enriched sample to two decimal places. (ii) The abundance of…

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Zadanie 5a

Aluminium has a low density, which is why it is widely used in aircraft and in specialized alloys. Aluminium is produced industrially by the electrolysis of aluminium oxide dissolved in molten cryolite, as shown in the diagram. (i) Outline why the molten…

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