A reaction uses the same solution concentration at 20 °C and 35 °C. A student explains the faster reaction at 35 °C by saying particles are larger and the activation energy has decreased.
Evaluate the explanation.
[4 marks]OCR Gateway GCSE Chemistry June 2024 Paper 4
5 questions on this paper's topics
26:001 of 5
A student says: "Crude oil is a compound. Fractional distillation breaks its molecules into simpler hydrocarbons. Each fraction contains one pure substance."
Evaluate each part of this explanation.
[4 marks]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]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]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]