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 Combined Science June 2023 Paper 10
5 questions on this paper's topics
27:001 of 5
A computer model displays 70 reactant particles and 30 product particles at equilibrium. During the next second 6 reactant particles change to product.
.1
Calculate the percentage of reactant particles that change to product in that second. Give your answer to at least two significant figures.
[2 marks].2
Predict the number changing back in the same second and explain why the display can stay at 70:30.
[2 marks]Two laboratory ecosystem models both remove carbon dioxide by photosynthesis. In model A all dead plant material decomposes. In model B some material is buried where decomposition is very slow.
Explain which model better represents long-term carbon removal and why the amount photosynthesised alone is not enough to predict the long-term atmospheric change.
[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]An early periodic table arranged elements strictly by increasing atomic weight and left no gaps. Another table allowed gaps and occasional changes of order to align similar reactions.
Evaluate why the second approach could produce a more useful table.
[6 marks]