Copper oxide is reduced by hydrogen: CuO+H2→Cu+H2O. A process must produce 12.8 g copper. Ar: Cu = 64, O = 16, H = 1.
.1
Calculate the minimum mass of copper oxide needed if conversion is complete.
[4 marks]
.2
Calculate the mass of hydrogen that reacts with this copper oxide.
[2 marks]
6 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
A student claims that diamond, graphite and fullerenes have identical properties because all contain only carbon.
Evaluate the claim by connecting structure to properties.
[6 marks]
5 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
A student electrolyses concentrated aqueous potassium chloride using inert electrodes in a teacher-controlled demonstration with suitable ventilation. Potassium is more reactive than hydrogen.
.1
Predict the electrode products and explain the difference from molten potassium chloride.
[3 marks]
.2
Explain how charge is carried through the aqueous electrolyte and through the external metal wires.
[2 marks]
6 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
A student says: "Evaporating a molecular liquid makes smaller molecules because the bonds break."
Explain what happens during evaporation and evaluate the student claim.
[6 marks]
4 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
An aluminium ion becomes an aluminium atom at an electrode. A student says that because aluminium is a reactive metal, this must be oxidation.
.1
Evaluate this statement using electron transfer, electrode identity and charge balance.
[3 marks]
.2
Write the balanced half-equation for this electrode change.
