Three repeated demonstrations with equal samples of a group 1 metal collect hydrogen volumes of 47, 49 and 48 cm³. A separate run collects 31 cm³ after the gas tube becomes loose.
.1
Calculate the mean volume from the three valid repeated demonstrations.
[3 marks]
.2
Explain why the low run cannot show that the metal was less reactive.
[2 marks]
5 marksFoundation and Higher5.3.1.1 Conservation of mass and balanced chemical equations
AQA Trilogy 8464
Spec and skills
Paper scope: C1
Spec 5.3.1.1
Original practice question
Answer and supported method checks
Propane burns completely in oxygen to form carbon dioxide and water. A sample uses 8.0 g oxygen and produces 6.6 g carbon dioxide and 3.6 g water. No products escape before weighing.
.1
Write the balanced equation for complete combustion of propane, C3H8.
[2 marks]
.2
Calculate the mass of propane that reacted.
[3 marks]
5 marksHigher5.4.1.2 The reactivity series
AQA Trilogy 8464
Spec and skills
Paper scope: C1
Spec 5.4.1.2
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.
[2 marks]
4 marksFoundation and Higher5.5.1.2 Reaction profiles
AQA Trilogy 8464
Spec and skills
Paper scope: C1
Spec 5.5.1.2
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]
5 marksHigher5.4.3.4 Electrolysis of aqueous solutions5.4.3.2 Electrolysis of molten ionic compounds
AQA Trilogy 8464
Spec and skills
Paper scope: C1
Spec 5.4.3.4
Spec 5.4.3.2
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.
