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]OCR Gateway GCSE Chemistry June 2022 Paper 4
5 questions on this paper's topics
28:001 of 5
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]A tank initially holds 2.0 dm³ of solution at 18 g/dm³. A 0.50 dm³ portion is removed after mixing, then 0.50 dm³ of water is added.
.1
Calculate the final concentration in the tank.
[4 marks].2
Explain why restoring the initial volume does not restore the initial concentration.
[2 marks]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]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]