Paper 3: Practical skills, all content and multiple choice

Cyclohexene is prepared by heating cyclohexanol with concentrated phosphoric acid and distilling the product. Explain why the product distils off while cyclohexanol largely remains.

Describe how the crude distillate is purified.

10.0 g of cyclohexanol (Mᵣ 100) gave 5.74 g of cyclohexene (Mᵣ 82). Calculate the percentage yield.

In an iodine clock experiment, the time for the blue-black colour to appear is measured at different concentrations of potassium iodide. Explain why 1/time can be used as a measure of initial rate and why only a small amount of sodium thiosulfate is added.

A graph of 1/t against [KI] is a straight line through the origin. State the order with respect to iodide and explain.

Give three variables that must be controlled.

A burette has an uncertainty of ±0.05 cm³ per reading and a pipette ±0.06 cm³. A titre of 23.50 cm³ was measured using a 25.0 cm³ pipette. Calculate the percentage uncertainty in the titre and in the pipette volume.

Give three steps that ensure an accurate titration.

Explain how the uncertainty in the titre could be reduced, and why using a larger volume reduces percentage uncertainty.

Describe tests that would distinguish between solutions of copper(II) chloride, iron(III) sulfate and ammonium carbonate. Give the observations.

Explain the observations when aqueous ammonia is added dropwise and then in excess to copper(II) sulfate solution.

Explain why the Haber process is run at about 450 °C and 200 atm with an iron catalyst, rather than the conditions that give the highest equilibrium yield.

Devise a three-step synthesis of propanone from propene. Give reagents, conditions and the type of reaction for each step.

Explain the trend in melting points across Period 3 from sodium to argon, linking each to structure and bonding.

Using E° values, explain why acidified potassium manganate(VII) can oxidise iron(II) ions but iron(III) cannot oxidise manganese(II) ions. MnO₄⁻/Mn²⁺ +1.51 V; Fe³⁺/Fe²⁺ +0.77 V.

How many moles of oxygen atoms are in 0.25 mol of CuSO₄·5H₂O?

Which species has the same electron configuration as Ar?

Which molecule is polar?

Which is the standard enthalpy of combustion equation for ethanol?

Which change increases the rate constant of a reaction?

For 2SO₂ + O₂ ⇌ 2SO₃ (ΔH negative), which change increases the equilibrium yield of SO₃?

What is the oxidation state of chromium in Cr₂O₇²⁻?

A reaction has ΔH < 0 and ΔS < 0. When is it feasible?

The rate equation is rate = k[X]². What happens to the rate when [X] is tripled?

What are the units of Kp for N₂(g) + 3H₂(g) ⇌ 2NH₃(g) with pressures in kPa?

Which is the strongest reducing agent? Ag⁺/Ag +0.80 V; Cu²⁺/Cu +0.34 V; Zn²⁺/Zn −0.76 V; Mg²⁺/Mg −2.37 V

What is the pH of 0.0010 mol dm⁻³ HCl?

Which element in Period 3 has the highest first ionisation energy?

Which Group 2 hydroxide is least soluble?

Which silver halide is insoluble in concentrated ammonia?

Which oxide is amphoteric?

What is the coordination number of Co in [CoCl₄]²⁻?

Which aqueous ion is the most acidic?

Which pollutant is removed by a catalytic converter?

Which compound shows E/Z isomerism?

Which alcohol is NOT oxidised by acidified potassium dichromate(VI)?

Which IR absorption is characteristic of an O–H group in an alcohol?

Which compound has a chiral centre?

What type of reaction is the acylation of benzene?

How many peaks are in the ¹³C NMR spectrum of propylamine, CH₃CH₂CH₂NH₂?

Which type of polymerisation forms poly(propene)?

Which bonds hold the α-helix of a protein in shape?

Which compound is used as the standard in NMR spectroscopy?

In column chromatography, which component elutes first?

Which reagent converts a nitrile to a carboxylic acid?