RP 3- Effect of temperature on a rate of reaction

Chemistry

How would you investigate how rate of reaction varies with temperature?

The reaction of sodium thiosulphate and hydrochloric acid produces a cloudy sulphur precipitate. To measure rate, time how long it takes the cross underneath the beaker to disappear. Repeat at 5 different temperatures and compare times

What are some issues with this method?

The cross disappearing is judged by eye so can be unreliable

There may be a delayed reaction time with the stopwatch

At low temperatures the reaction may be too slow

There may not be enough precipitate for the cross to disappear

How could you analyse the data?

Plot a graph of rate of reaction against temperature

What are the control variables in this experiment?

The concentrations of reactants and products

The volumes of reactants and products

Use the same beaker underneath

Use the same person to decide when the cross has disappeared