The sample was then reheated to the original state and the percent of the hydrate recovered was calculated by using the mass of the reheated sample by the mass of the original hydrate and then multiplied by 100%. Data Presentation & Analysis Table 1: The data was collected from the lab experiment. Sample calculations are shown. Mass of beaker with sample 30. Egg Mass of empty beaker 30. Egg Mass of sample . Egg Mass of beaker with sample after 1st heat 30. Egg Mass of beaker with sample after 2nd heat 30. Egg Heating mass difference Mass of anhydrite . Egg Mass of H2O . Egg Molar mass of Couch 135. G/mol Molar mass of H2O 18. G/mol Moles of anhydrous sample 2. Xx-3 moles couch Moles of H2O released 6. Xx-3 moles of H2O Mass % of H2O 21. 5% of H2O % Absolute error 0% absolute error Mass of reheated sample . 469 g % of hydrate recovered 93. 4% Couch H2O The samples were placed in a desiccators instead of being left to cool on the lab bench between each heating. This is because the beaker and contents would cause the mass of fluctuate when placed on the tarred balance if not cooled in the desiccators. This is used to store the beakers and the anhydrite so that the anhydrite does not absorb moisture from the air.
The sample needed to return to the oven for a second heating to insure that all of the water was heated off of the sample. If the mass difference between the first and second heating was greater than 0. Egg, the sample would have been needed to be heated a third time because all of the water had not yet been heated off. Sample calculations: Mass of the sample: Heating mass difference: Molar mass of Couch: Moles of the anhydrous sample: Mass % of H2O: % Absolute error: % of hydrate recovered: Conclusion The hydration number of water was found using the ratio of Couch moles and H2O moles.
The ratio was found to be 2 moles of H2O for every 1 mole of Couch. A new chemical equation of could be written using this psychometric ratio. The actual hydration number also is 2 moles of H2O. The calculated absolute percent error was found to be zero since the calculated hydration number was the same as the actual hydration number. It was also found that some of the reheated sample could not be recovered because some of the reheated sample remained stuck to the filter paper and was unable to be assured in the mass of the reheated sample. This did not allow the full sample to be recovered.
Questions 1 . The experimental hydration number resulted in being 2. The true hydration number is also 2. When % absolute error was calculated, the result was 0% error. Since the experiment concluded with no percent error, which means no error, there are no possible sources of error for the experiment. 2. Three significant figures were used to report the amount of anhydrite in moles and the amount of water released in moles. The way to determine the significant figures in this calculation was to look at the experimental value in the two equations, which is the mass.
The mass had 3 significant figures and the answer must have the same number of significant figures as the experimental value in this calculation. 3. When the anhydrous sample was reheated, only 93. 4% of the sample could be recovered. This was because some of the mass of the sample remained stuck to the filter paper and could not be measured in the final mass calculation. This automatically resulted in less mass and did not allow for 100% of the mass to be recovered. 4.
If the hydrate would have been overheated and had released a gas, there would have been excess mass released because the mass of the gas that would have been released and water released combined would have been greater than the mass of just the water released. The way to know if that had happened would have been if the mass of the water released would be over 2. 5. I believe that with a Bunsen burner to dry would have provided more accurate results for the hydration number because the heat can be applied more directly and the time to heat would be faster, giving less room for error in the data.