Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Physical Chemistry
442 practice questions
Topics covered
Practice questions
141–150 of 442
Question 141
1 mark · Easy
Answer and see the solution →Name the theory that explains how the frequency and energy of collisions affect the rate of chemical reactions.
Question 142
3 marks · Easy
Answer and see the solution →A student investigates how fast sodium reacts with water to produce hydrogen gas at room temperature.
(a)[1 mark]State what must happen to sodium and water particles for this reaction to occur.
(b)[1 mark]According to collision theory, what is a successful collision?
(c)[1 mark]Explain why the reaction rate might change during the experiment.
Question 143
2 marks · Easy
Answer and see the solution →A reaction in a beaker starts with 50 reacting particles per cm³. After a few minutes, only 10 reacting particles per cm³ remain.
Calculate the percentage decrease in the number of reacting particles per cm³ during the reaction.
Question 144
2 marks · Easy
Answer and see the solution →In a reaction, there are 40 effective collisions per minute at the start. After some time, the number of effective collisions drops to 12 per minute.
Calculate how many times faster the reaction was at the start compared to later. Give your answer as a number.
Question 145
2 marks · Normal
Answer and see the solution →Explain why not every collision between reactant particles in a chemical reaction leads to a reaction.
Question 146
4 marks · Normal
Answer and see the solution →A student adds excess powdered magnesium to dilute hydrochloric acid in a beaker. The mixture fizzes and gives off a gas.
(a)[1 mark]State the name of the gas produced in this reaction.
(b)[3 marks]Explain, using collision theory, why the reaction is faster at the start than near the end.
Question 147
3 marks · Normal
Answer and see the solution →A student investigates the reaction between sodium thiosulfate and hydrochloric acid at two different temperatures. The reaction is much faster at 45°C than at 25°C. Explain, using collision theory, why increasing the temperature increases the rate of this reaction.
Question 148
4 marks · Normal
Answer and see the solution →The graph below shows the concentration of hydrochloric acid over time during its reaction with excess calcium carbonate.
Concentration of hydrochloric acid vs time (a)[2 marks]Describe how the rate of reaction changes during the experiment.
(b)[2 marks]Explain the shape of the curve using collision theory.
Question 149
1 mark · Normal
Answer and check →Which statement best explains why a reaction only occurs when particles collide with at least the activation energy?
- A.It allows more particles to react with each other at low temperatures.
- B.It provides enough energy to break existing bonds for the reaction to occur.
- C.It increases the frequency of collisions between reactant particles.
- D.It makes the product more stable after the reaction.
Question 150
2 marks · Normal
Answer and see the solution →State the two conditions that must be met for a collision between reactant particles to lead to a reaction, according to collision theory.