Crucible dish Malachite
Spatula safety goggles
Bunsen burner Heat proof mat
Tongs Tripod stand
Safety:
To keep my experiment safe, I will wear safety goggles to protect my eyes. I will also do my practical quite a distance away from other people and the school equipment (on the practical bench) so nothing catches fire from the Bunsen burner. I will also use tongs carefully when carrying the hot crucible dish for weighing after the practical so I don’t burn my hands and also I don’t drop it.
Variables:
CONTROL VARIABLES:
My control variables would be the crucible dish and the amount of malachite sample I use. It would be because I will use the same crucible for all my experiment to keep the practical as fair as possible. If I use a different crucible for all the experiments then I’ll have to keep weighing it every time I repeat the experiment and if I forget to weigh it then the results produced would be inaccurate. I’ll also keep same the amount of malachite I use because I want to keep all the experiments fair and also I want to get results as accurate as possible:
DEPENDENT VARIABLES:
My dependent variable would be malachite sample because once an amount of malachite is decomposed, it can’t be used again for the same purpose. The amount of malachite used, however, would stay the same.
INDEPENDENT VARIABLES:
The independent variable would be the crucible dish and the amount of malachite. Before starting the experiments I will weigh the crucible dish and weigh it again with the malachite in it. I’ll weigh the crucible dish again after the malachite has decomposed to work out the amount of copper carbonate produced.
Method:
- Collect the apparatus (as mentioned earlier) and set it up as in the diagram below:
- Weight the crucible dish using a top-pan balance. Put about 2g of malachite in it and weigh it again to make sure of the total weight of the crucible dish with the malachite in it.
- Remove the top cover of the tripod stand and put a pipe-clay triangle on it and put the crucible dish on it and heat it using bunsen burner on the heat proof mat.
- Heat the crucible dish until all the malachite in it has decomposed. (that will take about 3-4 minutes)
- Use the tongs to lift the crucible dish and weigh it again using top-pan balance.
- Calculate the amount of the copper carbonate produced.
- Repeat the experiments twice to check the results and work out the average.
Results:
Observations during the practical:
I noticed that the malachite powder in the crucible was bubbling when it was being heated and the malachite on the side started to turn black first and then the malachite in the middle turned black. I also noticed some white specks in the malachite when all of it had turned black.
Analysing evidence:
CALCULATIONS:
EXPERIMENT 1
Mass of crucible = 18.29g
Mass of crucible + malachite = 20.29g
After heating = 19.84g
Mass of malachite used = 20.29g – 18.29g
=2g
Mass of residue = 19.84g – 18.29g
= 1.55g
Mass of CO2 lost = 2.00g – 1.55g
= 0.45g
0.45g of CO2 is produced from 124 x 0.45/44 of copper carbonate = 1.27g
Percentage of CuCO3 = 1.27/2.00 x 100 = 63.5%
EXPERIMENT 2
Mass of crucible = 18.29g
Mass of crucible + malachite = 20.29g
After heating = 19.84g
Mass of malachite used = 20.29g – 18.29g
=2g
Mass of residue = 19.84g – 18.29g
= 1.55g
Mass of CO2 lost = 2.00g – 1.55g
= 0.45g
0.45g of CO2 is produced from 124 x 0.45/44 of copper carbonate = 1.27g
Percentage of CuCO3 = 1.27/2.00 x 100 = 63.5%
EXPERIMENT 3
Mass of crucible = 17.88g
Mass of crucible + malachite = 19.88g
After heating = 19.44g
Mass of malachite used = 19.88g – 17.88g
=2g
Mass of residue = 19.44g – 17.88g
= 1.56g
Mass of CO2 lost = 2.00g – 1.56g
= 0.44g
0.44g of CO2 is produced from 124 x 0.44/44 of copper carbonate = 1.24g
Percentage of CuCO3 = 1.24/2.00 x 100 = 62%
CONCLUSION:
In the 3 experiments I did, I found out that the percentage of copper carbonate in malachite is usually around 60-70%. For two of the experiments I found out that there is 63.5% of copper carbonate in 2g of malachite which is about 1.27g. For the third experiment I found 62% of copper carbonate which is still quite close to 63.5%.
It also shows that my prediction I made in the Hypothesis was right which was based on the sample results.
For the first 2 experiments the amount of carbon di oxide produced was about 0.45g, the amount of copper carbonate was about 1.27g and the rest 0.28g were impurities found in malachite.
Evaluation:
I think that my method of doing the experiment was good and was quite safe too. As I mentioned in ‘Analysing Evidence’ section that 2 of my results were exactly the same but the third was bit different. It was different because the crucible dish I was dish broke just before the third experiment and the new crucible dish wasn’t as clean as the old one and that might have affected the results a bit. Both the crucibles were also different in weight.
I think that my results are pretty accurate but I think that they could’ve been more accurate if I had used the top-pan balance that gives the reading upto 5 decimal places rather than the one I used which only gives the reading upto 2 decimal places.
It would’ve been better if I had used the malachite in the rock form rather than using it in the powder form.
I could also time my experiments to get a better set of results.
As an extension I could go on and try to get pure copper from copper carbonate produced from malachite.
