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 2025 Paper 3
5 questions on this paper's topics
28:001 of 5
A student claims that discovering the electron was enough evidence for the modern nuclear model of the atom.
Evaluate the claim using the development of atomic models.
[6 marks]Copper oxide is reduced by hydrogen: . A process must produce 12.8 g copper. : Cu = 64, O = 16, H = 1.
.1
Calculate the minimum mass of copper oxide needed if conversion is complete.
[4 marks].2
Calculate the mass of hydrogen that reacts with this copper oxide.
[2 marks]In paper chromatography, dye A travels farther than dye B in the same time. Both start on the same line and the solvent front has passed both spots.
Explain the separation in terms of the mobile and stationary phases, and assess the suggestion that A must be a smaller molecule.
[4 marks]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]