Introduction
DrDAQ is used here with dual external temperature probes to compare the change in temperature of two test tubes containing bench hydrochloric acid both at 50 degrees Celsius. One is used as a control whilst 1 cm of magnesium is added to the other. This is carried out to investigate whether the exothermic nature of the reaction has a noticeable effect on the overall temperature of the reaction and hence effects the fair testing of the reaction. This approach can be used to gain high marks in the evaluation section of GCSE science coursework.
Equipment required
- DrDAQ data logger connected to a PC
- Two external temperature probes (DD100)
- 1 M hydrochloric acid
- 1 cm lengths of magnesium ribbon
- Two boiling tubes
- Electric water bath or large beaker filled with water at 50 degrees Celsius
- 25 cm3 measuring cylinder or 25 cm3 pipette
Experiment setup
- Measure out two lots of 20 cm3 hydrochloric acid and place in two test tubes
- Heat the hydrochloric acid to 50 °C in a water bath
- Monitor the temperature in both test tubes using the DrDAQ
- Add 1 cm of magnesium to one of the test tubes
- Monitor how the temperature changes in both test tubes
Figure 1: picture showing the set up of the experiment
Carrying out the experiment
Both test tubes need to be kept in the same environment for the experiment to be fair. The data collection should continue for as long as the temperature keeps changing.
Questions and discussion of results
- Did the magnesium reacting effect the temperature of the reaction?
- Would an increase in temperature matter as long as all the experiments went up by the same amount?
- How much did the magnesium reacting increase the temperature?
- How will this effect the design of the fair test for the reaction?
Further study
- How does the temperature of the reaction change if the acid concentration is lowered and the reaction takes longer.
- Is the temperature change always the same irrespective of length taken to react?
