Topics to revise
Rate of Reaction P2
Magnetism P2
Required Practical - Rate of reaction
Rate of reaction
Investigation into factors that effect the rate of reaction
Check your understanding with these quick common questions. Use the drop down boxes to see the correct answers.
Rate of reaction
This experiment investigates how factors such as concentration or temperature affect how quickly a reaction happens, showing that higher energy or more collisions make the reaction faster.
Independent variable: Concentration or temperature of a reactant or presence of a catalyst.
Dependent variable: Rate of reaction (gas produced per second or time for colour to change). Or in the thiosulfate and acid reaction, the time taken for a cross to disapppear is measured.
Control - Temperature, pH (in some reaction a buffer might be needed as the pH changes that can effect the rate of reaction).
Gas syringe or measuring cylinder, stopwatch, conical flask.
For the reaction between thiosulfate and hydrochloric acid, a cross is used under a beaker.
Improve accuracy: Use a gas syringe for precise gas volumes and repeat to find a mean. Gas escaping can reduce accuracy. Judging when you cannot see the cross is subjective.
Control validity: Keep acid volume, marble chip size, or total reactant volumes the same.
Description: As concentration or temperature increases, rate of reaction increases
Explain: because there are more frequent, energetic collisions.
When discussing temperature, also discuss the increased kinetic energy of particles.
Add dilute acid to a flask and connect a gas syringe.
Add marble chips and start the timer.
Record gas volume every 10 s.
Repeat with different concentrations and plot a graph.
For the thiosulfate reaction, the time taken for the cross to disappear is recorded.