Paper 3: Practical skills, all content and multiple choice

Describe how to determine the enthalpy change of a reaction between zinc powder and copper(II) sulfate solution using a polystyrene cup.

Explain why the student plots a temperature–time graph and extrapolates the cooling line back to the time of mixing.

50.0 cm³ of 0.500 mol dm⁻³ CuSO₄ was used and the corrected ΔT was 25.2 K. Calculate ΔH for Zn + CuSO₄ → ZnSO₄ + Cu. (c = 4.18 J g⁻¹ K⁻¹; density 1.00 g cm⁻³)

Describe tests to show that a solution contains ammonium ions and sulfate ions.

Explain why hydrochloric acid is added before barium chloride in the sulfate test.

Describe a test for carbonate ions in solution.

Describe how a pH meter is calibrated and used to follow a titration.

From a pH curve for a weak acid titrated with NaOH, the pH at half-neutralisation was 4.20. Explain how this gives Ka and calculate it.

Describe how to prepare a sample of an ester by heating an alcohol and a carboxylic acid, and why heating under reflux is used.

Give two safety precautions in this preparation.

Explain how the ester can be separated and how the presence of unreacted acid can be removed.

A student measures the rate of reaction of magnesium with acid by collecting gas in a syringe. Explain how the initial rate can be found from a volume–time graph.

A balance reads to ±0.01 g. Calculate the percentage uncertainty when 0.12 g of magnesium is weighed, and suggest how to reduce it.

Explain why collecting gas in a gas syringe is more accurate than collecting it over water in a measuring cylinder.

Use E° values to explain why vanadium(V) ions can be reduced to vanadium(II) by zinc in acid. (VO₂⁺/VO²⁺ +1.00; VO²⁺/V³⁺ +0.34; V³⁺/V²⁺ −0.26; Zn²⁺/Zn −0.76 V) State the colours.

Benzene can be converted into phenylamine in two steps. Give reagents and conditions for each step, name the intermediate and describe a test for phenylamine.

A 0.500 g sample containing iron was dissolved and all iron converted to Fe²⁺. It required 22.50 cm³ of 0.0180 mol dm⁻³ KMnO₄. Calculate the percentage by mass of iron. (Ar Fe = 55.8)

Explain why the enthalpy of lattice formation of MgO is much more exothermic than that of NaCl, and why experimental and perfect ionic model values can differ.

Which has the largest first ionisation energy?

What mass of NaOH (Mr 40.0) is needed to make 250 cm³ of 0.200 mol dm⁻³ solution?

Which shows hydrogen bonding between its molecules?

Mean bond enthalpies are less accurate than Hess cycle values because

Activation energy is

Adding more reactant to a system at equilibrium will

In 2Na + Cl₂ → 2NaCl, chlorine is

A reaction is feasible when

A zero-order reactant's concentration–time graph is

Kp for 2NO₂ ⇌ N₂O₄ has units of

In a cell, electrons flow in the external circuit from

Which is a Brønsted–Lowry base in HCl + NH₃ → NH₄⁺ + Cl⁻?

Across Period 3, electronegativity

Calcium hydroxide is used in agriculture to

Which halide ion is the strongest reducing agent?

Which Period 3 chloride reacts with water to give an acidic solution and HCl fumes?

Which ion is colourless?

Adding excess NaOH(aq) to a solution of Cr³⁺ gives

How many structural isomers have the formula C₅H₁₂?

Which reagent converts chloroethane into ethylamine?

The major product of adding H₂O to propene (acid catalyst) is

Oxidising butan-2-ol gives

Fehling's solution gives a brick-red precipitate with

The product of reacting propanoic acid with ammonia is

Benzene's carbon–carbon bond lengths are

Which is a secondary amine?

A polyamide is formed from

At low pH, an amino acid exists mainly as

In ¹H NMR, a peak split into a triplet has

Which converts a nitrile into a carboxylic acid?