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]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A student adds an alkali gradually to an acid. The measured pH values after successive additions are 2, 4, 6, 7, 9 and 11.
.1
Describe the change and identify the neutral reading.
[2 marks]
.2
Explain neutralisation in terms of the reacting ions.
[2 marks]
5 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
A supply of scrap contains iron and copper pieces. Iron is above copper in the reactivity series. A student proposes using the iron to obtain copper from a copper sulfate solution.
.1
Explain the reaction, its observation and a limitation of the proposed recovery method.
[3 marks]
.2
Suggest why the deposited solid should be washed and why it might still be impure.
