1.
State what is meant by rate of reaction. [1]
JD SCIENCE
Unit 5 worksheet — Rate of chemical change
Answer all questions. Show working. Answers are in a separate file on the Worksheets page — do not look at them until you have finished.
2.
State what is meant by collision theory. [1]
3.
State what is meant by activation energy. [1]
4.
State what is meant by a catalyst. [1]
5.
State what is meant by equilibrium. [1]
6.
State what is meant by Le Chatelier's principle. [1]
7.
State what is meant by the Haber process. [1]
8.
State what is meant by surface area. [1]
9.
State what is meant by a closed system. [1]
10.
State what is meant by a reversible reaction. [1]
11.
Owain is asked about rate of reaction in a WJEC Chemistry paper.
(a) Describe rate of reaction. [2]
(b) Explain why rate of reaction is important in this topic. [3]
12.
Owain is asked about collision theory in a WJEC Chemistry paper.
(a) Describe collision theory. [2]
(b) Explain why collision theory is important in this topic. [3]
13.
Owain is asked about activation energy in a WJEC Chemistry paper.
(a) Describe activation energy. [2]
(b) Explain why activation energy is important in this topic. [3]
14.
Owain is asked about a catalyst in a WJEC Chemistry paper.
(a) Describe a catalyst. [2]
(b) Explain why a catalyst is important in this topic. [3]
15.
Owain is asked about equilibrium in a WJEC Chemistry paper.
(a) Describe equilibrium. [2]
(b) Explain why equilibrium is important in this topic. [3]
16.
Owain is asked about Le Chatelier's principle in a WJEC Chemistry paper.
(a) Describe Le Chatelier's principle. [2]
(b) Explain why Le Chatelier's principle is important in this topic. [3]
17.
A gas syringe collects 30 cm³ in 20 s. Mean rate? [3]
18.
Mass falls by 0.80 g in 40 s. Mean rate of mass loss? [3]
19.
From a graph, the tangent at t=0 has gradient 0.40 cm³/s. What does this represent? [3]
20.
Concentration doubles and rate doubles. What is the order with respect to that reactant (A-level idea at GCSE: describe the effect)? [3]
21.
A reaction finishes in 80 s at 20°C and 20 s at 30°C. By what factor has the rate increased? [3]
22.
Haber: if 10 mol N₂ and 30 mol H₂ react completely, mol of NH₃? [3]
23.
Owain carries out the rate required practical (marble and acid, or sodium thiosulfate and acid). This is a typical WJEC required-practical style question.
(a) Identify the independent variable and the dependent variable. [2]
(b) State one control variable and explain why it must be controlled. [2]
(c) Suggest one improvement or source of error and how it affects the result. [2]
24.
Owain carries out investigating the effect of a catalyst on hydrogen peroxide. This is a typical WJEC required-practical style question.
(a) Identify the independent variable and the dependent variable. [2]
(b) State one control variable and explain why it must be controlled. [2]
(c) Suggest one improvement or source of error and how it affects the result. [2]
25.
Owain carries out drawing a rate graph from gas volume data. This is a typical WJEC required-practical style question.
(a) Identify the independent variable and the dependent variable. [2]
(b) State one control variable and explain why it must be controlled. [2]
(c) Suggest one improvement or source of error and how it affects the result. [2]
26.
Owain carries out the disappearing-cross (thiosulfate) practical. This is a typical WJEC required-practical style question.
(a) Identify the independent variable and the dependent variable. [2]
(b) State one control variable and explain why it must be controlled. [2]
(c) Suggest one improvement or source of error and how it affects the result. [2]
27.
Compare a catalyst with an increase in temperature. [4]
28.
Compare a powder with a large lump of the same mass. [4]
29.
Compare dynamic equilibrium with a finished irreversible reaction. [4]
30.
Compare increasing pressure (Haber) with increasing temperature (Haber). [4]
31.
Apply your knowledge of the Haber process to this situation: lower T favours yield but slower rate [3]
32.
Apply your knowledge of surface area to this situation: smaller SA [3]