Thiosulphate (doesn’t matter what the formula is but thio as a prefix indicates a sulphur compound) ions react with the hydrogen ions in acids to produce a thick precipitate of sulphur. The reaction happens faster at higher temperatures.

We can compare speeds of sprinters by measuring how long it takes for them to run a fixed distance, 100m. The world record held by Usain Bolt is quoted as a time, 9.58 seconds. The smaller the time taken to cover 100 meters the faster the speed.

We can time how quickly enough sulphur is produced by the thiosulphate ions to completely block a black band on the back of a test tube.The equation for this reaction can be written as:

Thiosulphate ions     +     hydrogen ions     —–>     sulphur     +     other products

Homework:

Watch the video. Decide how long it takes for each reaction in the video to produce enough sulphur to hide the black mark.Draw up a table of results. Plot a graph of temperature against time taken for the reaction( temperature goes on the horizontal axis, this is the variable you have control over.

Do an experimental write under the headings (on loose paper)

Aim

equipment 

Diagram

Method

table of results 

graph 

Conclusion. What happens to the rate of reaction as the temperature increases?

Discussion: Use particle theory to explain the effect of heat on the rate of reaction with thiosulphate and hydrogen ions. Words to use in the discussion include activation energy, kinetic energy, effective collisions, frequency of collisions.