Zadanie 1a
Outline the meaning of the term “homologous series”, with reference to the carboxylic acids.
Chemistry HL Paper 2, November 2023, TZ2
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Dodaj cały arkusz do zestawuZadanie 1b
Calculate the mass percentage of oxygen in ethanoic acid.
Zadanie 1c
Ethanoic acid and propanone, CH3COCH3, both contain a carbonyl group and have similar molar masses. (i) Explain, in terms of the strongest intermolecular forces present in each liquid, why propanone boils at a much lower temperature than ethanoic acid.…
Zadanie 1d
Ethanoic acid is a weak monobasic acid. The acid dissociation constant of ethanoic acid at 298 K is Ka = 1.74 × 10−5. (i) A student dissolved a sample of ethanoic acid in water and made the solution up to 2.00 dm3. Exactly 19.4…
Zadanie 2a
Explain why there has been so much recent research into this process.
Zadanie 2b
State the expression for Kc for this reaction.
Zadanie 2c
Bond enthalpies give an estimate of the enthalpy change of a reaction. Assume that all species are gases. (i) Use bond enthalpies from section 12 of the data booklet to determine the standard enthalpy change, ΔH⊖, of the forward reaction. (ii)…
Zadanie 2e
Calculate ΔS⊖ for the forward reaction, using the values given below together with section 13 of the data booklet.
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Zadanie 2f
The conversion of carbon dioxide to methanol is usually carried out over a catalyst containing copper and zinc oxide. (i) Sketch energy profiles for the forward reaction, with and without the catalyst, on the axes shown. Label ΔH and the two activation…
- Materiał graficzny
Zadanie 2g
Determine the oxidation state of carbon in methanol, CH3OH.
Zadanie 3a
State the name of the reagent that is heated with propanoic acid to form this ester.
Zadanie 3b
A student heated 3.85 g of propanoic acid with an excess of the second reagent and isolated 3.12 g of the ester. Determine the percentage yield.
Zadanie 3c
The conversion of propanoic acid into the ester can be followed by changes in spectra. (i) Compare the infrared (IR) spectra of propanoic acid and of the ester between 1500 and 3500 cm−1 by stating one feature they share and one feature in which…
Zadanie 3d
State the class of organic compounds to which CH3CH2COOCH3 belongs.
Zadanie 4a
(i) Calculate the enthalpy change for this reaction, using section 13 of the data booklet and the values given below. (ii) Outline why the entropy change of this reaction is expected to be small. (iii) Ignore the entropy change. Use your answer to (i) together…
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Zadanie 4b
Deduce the shapes of the CO2 and H2O molecules and explain why they differ.
Zadanie 4c
Iron has a number of natural isotopes. A sample of iron was enriched in to produce a mixture with the following composition: (i) Calculate the relative atomic mass of the enriched sample, giving your answer to two decimal places. (ii) Natural…
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Zadanie 5a
Outline the electrostatic attraction that holds a crystal of aluminium together.
Zadanie 5b
Aluminium is produced by the electrolysis of molten aluminium oxide (in industry dissolved in molten cryolite to lower the operating temperature). A simplified cell is shown in the diagram. (i) Outline why the molten mixture is classified as an electrolyte.…
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Zadanie 5c
Aluminium reacts with chlorine to form the chloride AlCl3. (i) Draw a Lewis (electron dot) structure for AlCl3. (ii) Outline in what respect this Lewis structure is unusual.
Zadanie 5d
In the gas phase some aluminium chloride exists as the dimer Al2Cl6, the structure of which is shown below. (i) Identify the hybridization of the aluminium atom in the dimer, Al2Cl6. (ii) Describe, in terms of Lewis acid–base behaviour, the…
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Zadanie 5e
Like aluminium chloride, iron(III) chloride forms dimers in the vapour phase. Iron, however, is a transition element and aluminium is not. (i) Outline, in terms of its electronic structure, what identifies a transition element. (ii) The graph shows the first…
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Zadanie 5f
(i) Calculate the standard cell potential for the reaction 2 Al(s) + 6 H2O(l) → 2 Al3+(aq) + 6 OH−(aq) + 3 H2(g) Use section 19 of the data booklet. (ii) Deduce whether this reaction is spontaneous under standard conditions at 298 K, and give a reason.
Zadanie 5g
Explain, in terms of nuclear charge, sub-levels and shielding, why magnesium has a higher first ionization energy than both sodium and aluminium.
Zadanie 5h
Outline how data from the atomic emission spectrum of aluminium could be used to find its first ionization energy.
Zadanie 6a
Butanone can be synthesised from but-1-ene in a two-stage process. In the first stage the alkene reacts with water in the presence of sulfuric acid to form the intermediate compound [X]; in the second stage [X] is converted into butanone by reagent B. (i) Draw…
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Zadanie 6b
Benzene is converted into nitrobenzene by heating it with a mixture of concentrated nitric and sulfuric acids. The attacking species is the electrophile NO2+. Explain the mechanism by which benzene is nitrated by NO2+, showing the movement of…
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Zadanie 6c
The rate constant of a reaction at 40 °C is 2.5 times its value at 30 °C. Deduce the activation energy of the reaction, in kJ mol−1. Use sections 1 and 2 of the data booklet.