Collision theory and rates of reactionEdexcel A-Level Chemistry: Mind map

Exam questions on Collision theory and rates of reaction

1. A technician reacts marble chips (calcium carbonate) with dilute hydrochloric acid and wants to understand how the rate of the reaction can be controlled.
   Define the term activation energy and explain why most collisions between particles do not lead to a reaction.2 marks
2. A class investigates how temperature affects the reaction between sodium thiosulfate solution and dilute hydrochloric acid, which produces a pale yellow precipitate of sulfur. They time how long it takes for the cloudiness to hide a cross marked on paper under the flask.
   The cross disappears after 80 s at 20 °C and after 41 s at 30 °C. Calculate the rate of reaction, as 1/time, at each temperature and the factor by which the rate increases.2 marks
3. A student reacts an excess of marble chips with 50 cm³ of dilute hydrochloric acid and measures the volume of carbon dioxide collected in a gas syringe at regular intervals, then plots volume against time.
   A tangent drawn to the curve at time zero passes through the points (0 s, 0 cm³) and (30 s, 33 cm³). Describe how the initial rate is found from the graph and calculate its value.3 marks