Determination of Copper Oxide's Empirical Formula: Experimental Data and Calculations - Pr, Lab Reports of Chemistry

Download Determination of Copper Oxide's Empirical Formula: Experimental Data and Calculations - Pr and more Lab Reports Chemistry in PDF only on Docsity! Date Performed: 10/2/09 Name: Saba Sadeq Date Submitted: 10/6/09 Partner: Kara Smalley Instructor: Sevilay Bilgin Determination of a Chemical Formula Objective The objective of this lab was to determine the percentage composition and the empirical formula for an oxide of copper by its reduction with methane gas at approximately 500C. Experimental Data: Mass of test tube: 17.39 g Mass of test tube and sample: 19.49 g Mass of sample: 2.1 g Mass of test tube and sample (after being heated): 19.09 g Mass of sample (after being heated): 1.7 g Sample Calculations: Mass percents of copper = mass of Cu = 1.7 g = 81.0% Mass of CuxOy 2.1 g Mass percents of oxygen = mass of O = 0.4 g = 19.0% Mass of CuxOy 2.1 g grams of Cu = 1.7 g = 0.028 mol of Cu mol of Cu 63.55g/mol Uncertainty: 1.7 g  0.01 63.55g/mol Sr^2 = (0.01)^2 + (0.01)^2 0.028 1.7 63.55 Sr= 1.69 x 10^-5 0.028  (1.69 x 10^-5) grams of O = 0.4 g = 0.025 mol of O mol of O 16.0 g/mol Uncertainty: 0.025 g  0.01 16.0 g/mol Sr^2 = (0.01)^2 + (0.01)^2 0.025 0.4 16.0 Sr = 6.41 x 10^-6 0.025  (6.41 x 10^-6) 1.27 1 1.19 1.19 1 1.19 Estimated Standard Deviation: (1.7  0.01) + (0.4  0.01) = 2.1 (0.01)^2 + (0.01)^2 = 2.1  0.01 In a 100 gram sample… 81.0% is Cu = 81.0 grams Moles of copper = mass of Cu = 81.0 g = 1.27 moles molar mass 63.55 g 19.0% is O = 19.0 grams Moles of oxygen = mass of O = 19.0 g = 1.19 moles molar mass 16.0 g Results and Conclusions: Mass (grams) Mass percentage in the oxide (%) Moles Copper 1.70 grams 81.0% 0.028 mol Oxygen 0.40 grams 19.0% 0.025 mol From the mole ratio we can see that the sample in the test tube was in fact Cu(II)Oxide, a one to one mole ratio. Discussion of Experimental Uncertainty: The most obvious source of experimental uncertainty is the possibility of the reaction not fully completing when we turned off the bunsen burner. Meaning not enough time was given for the CuO to completely chemically react with the reducing