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 beaker becomes colder when two substances react. A student sketches a reaction profile with products below reactants and no energy barrier.
Explain how the profile should be corrected and what each correction means.
[4 marks]
6 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
A student gives this explanation: "An exothermic reaction has weak product bonds. Breaking the reactant bonds releases energy, and activation energy is the same as overall energy change."
Evaluate the explanation using bond breaking, bond formation and reaction profiles.
[6 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]
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.
