The new formula is
Mg + HCL → MgCl + H2
Preliminary Evidence
The preliminary evidence experiment shows that the temperature increases which makes it an exothermic reaction. This may be because the bonds produced are closer than the bonds being broken.
Fair test ideas
To make the experiments fair I would need to keep the volume of hydrochloric acid the same and the same concentration. The only thing wouldn’t change is the variable I have chosen to study which is the length of magnesium ribbon. To make the results more accurate and fair I could repeat the experiments several times.
Apparatus
- Measuring cylinder
- Plastic cup
- Thermometer
- Goggles
- Ruler
- Magnesium ribbon
-
25cm3 of 0.5 hydrochloric acid per experiment
Diagrams
Method
- Place 25cm of 0.5m HCL in a cup
- Take down the temperature using a thermometer with out the magnesium ribbon
- Add one piece of magnesium ribbon
- Take down the temperature when you are unable to see the magnesium ribbon or when the temperature stops increasing
- do the experiment each time changing the variable and repeat the experiment twice to make the results more accurate
Results
1st experiment
2nd experiment
Analysis of results
From the experiment I can see the less magnesium ribbon I put in the lower the temperature is. The more the magnesium ribbon the higher the temperature rises this is because more bonds are being made which means the reactions are exothermic as it gives out heat.
I’ve worked out that a 4cm piece of magnesium needs 1365 joules.
Joules = mass (g) X specific heat capacity X change in temperature
Joules = 25g X 4.2 X 13
4cm = 1365 joules
6cm =1680 joules
8cm =1575 joules
10cm =1680 joules
4cm =945 joules
6cm =1260 joules
8cm =1470 joules
10cm = 1995 joules
There is a trend beginning to appear which is the larger the magnesium the more energy is released.
The average of the 1st experiment is
1365+1680+1575+1680= 6195
6195 = 1548.75
4
The average of the 2nd experiment is
945+1260+1470+1995= 5670
5670 = 1417.5
4
Conclusion
I think that my experiment went well. I found out what I needed to find out and proved my hypothesis correct. The first results didn’t have a reliable trend but the second results did. If I was to devise a new hypothesis to test I could use Catalyst and see how much of a difference it would make to the temperature. For the next experiment I would add catalyst to the experiments.
Evaluation
My results for the first experiment weren’t very accurate but the second results increased in more of a trend. There were a couple of anomalous results. This may be because I used a higher mole hydrochloric acid. To make the test fairer I should have the same mole in the first experiment. But on for the second test the results from that were enough to draw conclusion that related to the hypothesis. I think that I did repeated the experiments enough.
