A catalyst changes the highest point of a reaction profile from 170 kJ to 115 kJ. Reactants remain at 40 kJ and products at 15 kJ.
.1
Calculate the catalysed activation energy.
[2 marks]
.2
Evaluate the statement: "The catalyst releases an extra 55 kJ, so the reaction becomes more exothermic."
[2 marks]
6 marksFoundation and Higher5.4.3.3 Using electrolysis to extract metals
AQA Trilogy 8464
Spec and skills
Paper scope: C1
Spec 5.4.3.3
Original practice question
Answer and supported method checks
A factory uses electrolysis to extract aluminium. One operating mixture needs 1200 energy units per batch; adding cryolite reduces the requirement to 900 units per equal batch.
.1
Calculate the percentage reduction in energy use.
[3 marks]
.2
Explain how cryolite reduces energy use and why the positive electrodes need replacement.
[3 marks]
5 marksFoundation and Higher5.1.2.6 Group 75.1.2.5 Group 1
AQA Trilogy 8464
Spec and skills
Paper scope: C1
Spec 5.1.2.6
Spec 5.1.2.5
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]
6 marksFoundation and Higher5.2.2.4 Properties of small molecules
AQA Trilogy 8464
Spec and skills
Paper scope: C1
Spec 5.2.2.4
Original practice question
Answer and supported method checks
Molecular substance A boils at 40 °C and molecular substance B boils at 140 °C. Their covalent bonds remain intact when they boil.
.1
Explain the difference in boiling point.
[2 marks]
.2
Calculate the boiling-point difference.
[2 marks]
.3
Explain why these boiling points alone cannot establish which substance has stronger covalent bonds.
[2 marks]
5 marksFoundation and Higher5.4.1.1 Metal oxides
AQA Trilogy 8464
Spec and skills
Paper scope: C1
Spec 5.4.1.1
Original practice question
Answer and supported method checks
A steel object of mass 45.0 g is left in damp air. After all loose material is retained, the object and corrosion products have mass 47.7 g.
.1
Calculate the percentage increase in mass.
[3 marks]
.2
Explain why the increase does not contradict conservation of mass.
