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In this experiment, I plan to find out how much Zinc oxide is present in Calamine solution (a solution that stops itching). I will do this by working out the amount of Zinc Oxide produced by Zinc Carbonate once it has been heated, causing thermal decomposition and the release of carbon dioxide gas. A carbonate is a salt of carbonic acid when carbon dioxide (CO2) dissolves in water. When combustion takes place, CO2 is a product along with another substance; in our case, zinc oxide. Here is the chemical equation: Zinc Carbonate (s) ==> Zinc Oxide (s) + Carbon dioxide (g) ZnCO3 ZnO CO2.
With this, you can find out the theoretical yield that you will receive from the calamine lotion. You do this using the element’s relative atomic mass. As the equation has already been balanced, you work out how much (in grams) you will produce. As zinc carbonate is relatively unstable, it is able to decompose into zinc oxide and carbon dioxide. Because zinc oxide is stable, it shall not decompose any further, Therefore, from 125grams of calamine lotion, you will harness 81grams of zinc oxide and 44grams of carbon dioxide. I will discuss the theoretical yield and how to calculate it later on within the method.
I predict the amount of zinc oxide from the lotion shall bear resemblence to the actual patter of the theoretical yield quite closely. The amount of zinc oxide should rise in conjuction with the amounts of calamine lotion. Also, when the produce of zinc oxide increases, so should the levels of carbon dioxide. Method In the experiment, I have been detailed the following equipment to use: The calculation of the theoretical yield will help me during the experiment. By calculating it, I am able to tell how much the zinc oxide should weigh when the reaction is over. Also, I am able to compare it with my results to produce a graph.
To calculate the theoretical yield, you can start by dividing the amount of particles inzinc oxide (81g) by the amount of particels calamine lotion (125g). then you times it by the amount of calamine lotion you are going to use, (eg, 0. 4). Therefore, 81g divided by 125g multiplied by 0. 4. In the actual experiment, we will be given 10g of calamine lotion to use. Using our quantities, we will thermal decompose the calamine lotion. Measuring out the exact amounts of calamine lotion into the test tube, we will heat it for 5minutes at first at the tip of the blue flame.
After 5 minutes have passed, I will weigh it to see whether the reaction has finished. If not, I shall keep heating it for two minutes at a stretch until the reaction has finished, then record my results in a table. I will do this six times, then do repeats and take the average. This way my answer’s accuracy will be greatly improved. During the experiment, I expect to obtain results on the yield of zinc oxide in accordance to the theoretical produce. However, I am not going to measure the amount of carbon dioxide. Instead, I will be able to see when the reaction has ceased because of the ‘bubbles’.
When thermal decomposition takes place, these bubbles are made through the release of carbon dioxide. Therefore, when the bubbling has stopped, so has the reaction. To make the experiment as safe as possible, goggles wwill be used when heating up the zin carbonate within the test tube. To stop the carbonate from spewing out of the top, I will put mineral wool just inside. This lets through the carbon dioxide, but in theory will keep in the zinc carbonate. The test tube will be fixed in an appropriate angle, so that if anything does spill out of the top, it shall not hit anyone.
Also, normal lab procedures such as tying lose objects (such as hair, ties etc) back. To make this a fair test, I will change only one variable throughout the process; the amount of calamine lotion in the test tube. Time is not a big factor, as after five minutes, the compound shall be weighed. It will be heated for two minutes at a time until the reaction has finished. The bunsen burner shall always be at the same distance of the test tube, at the tip of the ‘blue flame’ which is the hottest part. Most importantly, the amounts of calamine lotion shall be weighed nearly exact to 2 decimal places to make it as exact as possible.