I have decided to use six quantities of calamine lotion in each experiment. These shall be; 0. 4g, 0. 6g, 0. 8g, 1. 0g, 1. 2g and 1. 4g. This way, I shall not be using vast amounts of calamine solution. Also, there is less margin for error using smaller amounts, making my results more accurate. On top of that, I am able to do repeat experiments with the left over chemicals, so I can take an average making my results even more reliable. Obtaining After having done the experiment, I have gathered together the following results.
In this table, I will show the results of both preliminary results and repeats and an average to go with those two. Then, tabulating the results from another group, I am able to contrast it with my own answers. Lastly, I will include the theoretical yield to show how accurate my answers are. Amount of Zinc Carbonate Results (g) Theoretical yield(g) Preliminary Repeat Another group Average.
Analysis (see graph attached) My results show reasonable accuracy to the theoretical yield. Combining my results with those of another group seems to have been effective, as there becomes less room for error. I was never more than 0. 05g out, and in some I have matched the theoretical yield. My percentage yield has fluctuated from 100% to 113%, which I think is a good extent of accuracy. I have noticed that my actual yields have never been below the theoretical yield, suggesting that either the reaction hadn’t quite finished, or an outside object was affecting the experiment.
Concluding this investigation, I feel that I have constucted my evidence well, having been accurate, doing repeat experiments, and averaging these out with another group. My yields have risen in accordance to the amounts of calamine ltion used, meaning that my prediction istrue to what happened. Because there is more calamine lotion, there are more particles involved, and when it thermally decomposes there will be more zinc oxide remaining. In theory, the only product that leaves the test tube will be the carbon dioxide so in ideal conditions the results should exactly match the theoretical yields.
Evaluation The experiment has been successful because of the accuracy of my results. The procedure that I have used has been right for the nature of the investigation, and the quality of my evidence has been good. The only anomaly, if any was the experiment using 0. 6g of calamine lotion. Whereas my percentage yields had varied between approximately ! 00% to 105%, the percentage yield in this case was 113% which is quite a long way off target for the precision that I was aiming for. To improve this, with time allowing I should have repeated the experiment a further time.
The anolomaly could have been due to too much calamine lotion, but for this to happen twice is strange. However, I feel that the reliability of the evidence is sufficient enough to support the conclusion, as I have even calculated an average percentage yield, 103%. This shows that even with the anomaly, the experiment has been very precise. To furthen the investigations scientifical merit, would have been to harness and record the amount of carbon dioxide let loose. Doing this may not be exactly accurate, but even just counting the bubbles emitted by the thermal decomposition would have given us an even better idea of accurateness.