Equipment Required
For this experiment the following apparatus are both suitable and are to be required:
Heat Proof mat
Bunsen Burner
Test tubes (x5)
Test tube Holder
Electronic Scale (more accurate than normal ones.)
Mineral Wool
Calamine
Goggles (safety precaution)
Tongs
Preliminary Work
A similar experiment was done before in order to be familiar with the process and help base our experiment on this. This involved obtaining copper oxide from malachite. The process was similar to that which will be done in this experiment. The quantities of the previous test were a suitable amount hence we will use this into our test which we are doing now.
Theoretical Amounts
Amounts
Formula:
ZnCO3 ZnO + CO2
C=12
O=16
Zn=65
ZnCO3 ZnO + Co2
RFM 125g 81g 44g
0.5g = 81/125 x 0.5 = 0.65 x 0.5 = 0.32g
1.0g = 81/125 x 1.0 = 0.65 x 1.0 = 0.65g
1.5g = 81/125 x 1.5 = 0.65 x 1.5 = 0.97g
2.0g = 81/125 x 2.0 = 0.65 x 2.0 = 1.30g
2.5g = 81/125 x 2.5 = 0.65 x 2.5 = 1.62g
3.0g = 81/125 x 3.0 = 0.65 x 3.0 = 1.94g
3.5g = 81/125 x 3.5 = 0.65 x 3.5 = 2.23g
Suitable Number and Ranges
A suitable range of number of readings would be about 7. The previous experiment had the same amount of readings and was sufficient enough to draw conclusions. The weight of each will range from 0.5g to 3.5g. The range is suitable as it is amounts which are able to fit in a test tube. The intervals are at 0.5g which is accurate enough to see any patterns or changes in the weight of the calamine.
Accuracy
The precautions for accuracy in this test must be taken into account. The mineral wool aids in helping stop the gases from escaping. The other factors to consider is that we must keep a constant record of the weight in order to know when the material has been all burnt. For more accurate results we could repeat the experiment several times. However at this current time it is not feasible.
Pre testing
Work has to be carried out in order to record correct readings. Before the calamine is added to each test tube, we need to weigh the test tube and the mineral wool by itself. This is to be done as we need to measure the weight of the test tube and its contents when heating. The contents can then be added to the test tube weighing them at appropriate masses. When the calamine has decreased to a constant level, we deduct the weight of the test tube and mineral wool in order to find the weight of the contents inside.
Obtaining Results
Method
- Set up Bunsen Burner ensuring that the mat is underneath and goggles are worn.
- Place Mineral Wool on top of test tube, ensuring to use tongs to pick it up.
- Weigh the weight of the test tube and mineral wool, recording it.
- Place the appropriate amount of calamine according to the amounts needed to be tested.
- Burn the calamine over a blue flame on the Bunsen burner, using a test tube holder to hold it.
- After 2 minutes of burning weigh the test tube
- Continue burning until the weight of the test tube is constant. This is when we know all which can be burnt has been finished
- Deduct the weight by the weight of the test tube and mineral wool to get result.
- Repeat for the different weights.
Diagram
Results
Graph
Analysis of Results
The results above show that they are more than the theoretical amounts. Thus this means that the results are slightly more and hence the percentage yield will be above 100%. This is an unexplainable result, as the mineral wool should have been sufficient in letting out all the CO2 and leaving the amount of zinc oxide stated.
Percentage Yield
Formula:
%Yield = Actual Amount / Expected Amount x 100
0.5g = 0.39g / 0.32g x 100 = 121%
1.0g = 0.75g / 0.65g x 100 = 115%
1.5g = 1.10g / 0.97g x 100 = 113%
2.0g = 1.46g / 1.30g x 100 = 112%
2.5g = 1.58g / 1.62g x 100 = 97%
3.0g = 2.07g / 1.94g x 100 = 106%
3.5g = 2.42g / 2.23g x 100 = 108%
The reasons for these results are that the burning process has given a more efficient result than that shown in the theoretical values.
Supporting the Prediction
In my prediction I had stated that the results would be as they are now. The prediction was correct in saying that there would be a degree of inaccuracy due to undetectable sources, perhaps a result of efficiency of burning rather than a deficiency.
Conclusion
The results show that calamine draws out zinc oxide at a different rate. In the experiment which has just been done, the results came out accurate and sufficient. The %yields show this. The number does vary around 100%, some dropping just below it or just above. These results are good and are stable enough to draw this conclusion.
Evaluation
The results in the test were satisfactory to the testing. The results were good. The factors in which effected the results were taken into account and dealt with sufficiently. Thus there were some efficient results. The results however were anomalous. These results could have been wrong due to unexplainable factors. The results would have also been better if the test was run out several times and an average was taken. This however was not feasible due to the practicality of time. Also to be taken into account is the method of burning we used. It is shown as efficient to a certain degree of accuracy but are there any other tests which will prove as any better. If so, will it take into account any of the unknown inaccuracies which had arose in this test.
I felt that the mineral wool did do its purpose very well. It was suitable and was effective.
The graphs do compliment each other pretty well. The evidence is reliable enough to draw conclusions from. The result I feel were good as we took into account the fact that the material had to be heated several times before the zinc oxide will be fully made.
