1.1. A student uses this apparatus in an experiment to study the rate of the reaction between zinc and dilute sulfuric acid.

This is the student’s method.

• Add a few zinc granules to a conical flask on a balance

• Add 100 cm³ of dilute sulfuric acid to the flask, start a timer and immediately record the mass of the flask and contents

• Record the mass of the flask and contents every minute until the mass remains constant

The mass of the flask and contents decreases because hydrogen gas is produced and leaves the flask.

The student uses the mass readings to calculate the total mass of hydrogen produced.

Complete the equation for the reaction by adding the state symbols. 

 Zn (................) + H₂SO₄ (................) → ZnSO₄ (................) + H₂ (................)

1.2. The table shows the student’s results.

 i) Plot the student’s results. The first three have been done for you.

 (1)

 ii) Draw a circle around the anomalous result.

 (1)

 iii) Draw a curve of best fit.

 (1)

 iv) Give a possible reason for the anomalous result.

 (1)

 v) Determine a more likely value for this result.

 (1)

1.3. i) Explain how the shape of the curve shows how the rate of the reaction changes as time increases.

 (2)

 ii) At the end of the experiment there is no zinc left in the flask.

 Give a conclusion the student could make from this observation.

 (1)

1.4. The student does another experiment using

• the same amount of similarly sized magnesium granules instead of zinc

• the same volume of sulfuric acid, but of a lower concentration

Explain why it is difficult to predict how the rate of reaction in this experiment compares with the rate of reaction in the first experiment.

1.5. Explain, in terms of particle collision theory, how increasing the temperature affects the rate of a reaction.