Instead of just attempting this question on paper, have a go at it from a practical perspective. DO the experiment.
Collect the results, analyse and evaluate both the results and the experimental procedure. It will improve your application, analytical and evaluation skills. It will also make it reel and is fun.
If you found this useful, do another.
You don't need test tubes. Small drinking glasses or jars will do the job. Make sure they are the same size though.