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]Edexcel GCSE Chemistry June 2022 Paper 2H
5 questions on this paper's topics
24:001 of 5
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 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]A bottle contains carbon dioxide molecules. A sample of magnesium chloride contains and ions.
.1
Compare how bonds form in the two substances.
[3 marks].2
Explain why one magnesium atom needs two chlorine atoms to form the compound.
[2 marks]A sample contains very long covalent molecules. It softens when heated, does not conduct electricity and becomes solid again on cooling.
Explain these observations using a polymer model.
[6 marks]