Students compare two catalysts for the decomposition of hydrogen peroxide. Each trial lasts 60 s; the same solution volume and concentration are available.
Plan an investigation to compare the rates fairly and assess whether a catalyst is used up.
[6 marks]
5 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
Chlorine atoms have electron arrangement 2,8,7. Iodine atoms have more occupied electron shells but also seven outer electrons.
.1
Explain why chlorine is more reactive than iodine.
[3 marks]
.2
Compare this trend with the reactivity trend down group 1.
[2 marks]
4 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
Copper is recovered from a leachate by electrolysis with inert electrodes. The solution contains copper ions. A student claims that the current turns the bacteria into copper atoms.
Explain the actual electrode process and distinguish bioleaching from the recovery step.
[4 marks]
6 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
Dilute hydrochloric acid is added to excess copper oxide. The black oxide becomes a blue-green copper chloride solution, with black solid remaining.
.1
Write the balanced equation.
[2 marks]
.2
Explain why excess copper oxide is used and how it is removed.
[2 marks]
.3
Explain why the mass of wet crystals would overestimate the mass of salt recovered.
[2 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A town collects 12 tonnes of glass. Sorting removes 8% as contamination. All remaining glass can replace virgin glass material in this simplified model.
.1
Calculate the mass available to replace virgin material.
[2 marks]
.2
Explain why reducing packaging use can give benefits beyond recycling the same mass.
