Firstly weigh one of the test tubes (presuming they are all the same weight) to ascertain each ones weight. Using a spatula measure 1g of calamine into one test tube. Plug the test tube with sufficient mineral wool using tongs to avoid contact with hands and thus avoiding any irritation that may occur. Mineral wool will prevent spillage. Then re-weigh the test tube containing both the mineral wool and the calamine. Record these weights into a table.
Heat the test tube until there is a significant change in colour. Leave to cool, repeat process for 1.5g, 2g, 2.5g, 3g, and 3.5g of calamine doing two of each as to work out an average later. Check that test tube one has cooled down then weigh and record results. Repeat for other 11 test tubes. Repeat this heating, cooling and weighing process until the weight of each test tube remains unchanged for two consecutive weighs. Record all final weights, and from results work out how much zinc oxide has been produced in each test tube this can be done with the following equation:
Weight of Zinc Oxide Produced=
Weight of Calamine used – (Starting weight – End weight)
The two weights in the brackets must contain both the calamine and mineral wool.
Results:
Theoretical conversion chart:
ZnCO³ ZnO+CO²(already balanced)
One mole of ZnCO³ gives 1 mole of ZnO
(C=12, O=16, Zn=65)
ZnCO³ ZnO
65+12+48=125 65+16=81
One gram of ZnCO³ gives 81/125=0.648 grams of ZnO
To compare the theoretical conversion chart with the results I gained I will work the percentage yield. This is done by taking the actual amount gained dividing it by the expected amount (theoretical) and times by 100. Here are the percentage yields I worked out.
Analysis of results:
For both the theoretical conversion line and the results I gained line we see that they both show strong positive correlation. Matter cannot be destroyed or created so it is logical that there is direct correlation on the yield generated. I can conclude that these results were to be expected because scientific say that the amount of zinc oxide produced will be directly proportional to the amount of calamine used. By using the percentage yield table we can see that the amount of Zinc Oxide produced was way above what it should have been. Also from viewing the percentage yield table we can also see that the amount of Zinc Oxide produced was above the expected amount. This would be due to one main reason, that measuring of the calamine could have been inaccurate.
Evaluation:
For more accurate results you could have weighed each test tube in case there is any cracks or blemishes on the test tube that would affect the results. Also we did not use 0.5 grams of calamine. We could of also used greater amounts of calamine to check that the correlation continues. We could have also used a different compound in the same group to see if we got similar results.
