Apparatus
- Magnesium
- Hydrochloric acid
- Thermometer
- Bunsen burner
- Test tubes
- Test tube holder
- Measuring cylinder
- Beaker
- Safety goggles
Safety
Follow all the rules on safety while performing an experiment in the laboratory for example:
- Wear safety goggles at all times
- Put all stools away
- Never sit down during an experiment
Method
-
Measure out 3cm3 of hydrochloric acid.
- Cut a piece of magnesium to 1cm in length.
- Measure the temperature of the hydrochloric acid at the start.
- Pour hydrochloric acid into test tube and add magnesium.
- Record time taken for magnesium to fully dissolve.
- Repeat steps 1 – 5 at different temperatures
Results tables
1st set of results
2nd set of results
Analysis
There was no trend from the first set of results, there a number of reasons why this may have happened. This was a fault in the experiment. In the second set of results the trend was the higher the temperature the quicker the rate of reaction apart from the first result which was an anomaly.
In the first set of results my prediction did not apply, I would never have expected these results, they were so mixed up. For the second set of results my prediction did apply apart from the first result which was an anomaly so apart from that the higher the temperature of the acid the quicker the rate of reaction.
As there is more heat energy added to the H+ ions will collide with each other more frequently thus causing an increased rate of reaction between the acid and magnesium.
Hydrochloric acid + Magnesium Hydrogen + Magnesium Chloride
2HCL + Mg H2 +MgCL2
Evaluation
There were many errors in this experiment, some of these errors were:
- The thickness of the magnesium could have varied (this means the surface area on each piece of magnesium would have been different, affecting the rate of reaction).
- Magnesium floats on the surface of the acid meaning it is only the bottom of the magnesium that reacts with the acid. This may affect the time taken for the magnesium to fully dissolve
- As you carry out the experiment the acid has time to cool down (after heating)
- Sometimes the magnesium would stick to the side of the test tube
You could improve this experiment by using these methods:
- To solve the temperature problem, use a controlled environment and change the temperature of that environment so the acid will not cool down.
- Use a template to cut the magnesium into equal strips
In my experiment there was one anomaly it was the first result in my second set at 26oc it took 21 seconds for the magnesium to fully dissolve but it then took the magnesium 33 seconds to dissolve at 36oc from then on the trend was the higher the temperature the quicker the reaction.