Ch 9-7-07 200-42
Experiment one
Proving Dalton's Law of Proportions
Experiment one:
Purpose: The purpose is to validate Dalton's law of proportions in part one and further back up our findings through experimentation in part two.
Data and Calculations: Mass of magnesium: .15g Mass of magnesium oxide formed: .24g Mass of oxygen from the air: .09g Moles of Mg: .15g Mg /24.31g Mg = .006 Mol Mg. Moles of O: .09g O/16g O= .0056 Mol O. Closest whole number ratio is 1:1 5. Chemical Formula for Magnesium oxide is MgO 6. 2Mg+O2 --2MgO Percent Error: ((.006-.0056)/.006)*100= 6.66% error Part II: Mass of hydrated copper (II) sulfate: 5.53g Mass of anhydrous copper (II) sulfate: 3.65g Mass of lost water: 1.88g Moles of CuSO4: 3.65g/159.62= .022 Mol. Moles of H2O: 1.88g/18.01= .104 Mol. 5. Moles of H2O per mole of CuSO4= 5 Formula for copper (II) sulfate hydrate: CuSO4 *5H2O 6. CuSO4 *5H2O CuSO4 + 5 H2O
Error: Possible sources of error come from random and systematic sources. Random sources include the inclusion of other particles performing while the experiment. Systematic may include inaccuracies in the measurement devices themselves. As the only measurement device that was used was a scale the accuracy was negated after two decimal places.
1. 2. 3. 4.
1. 2. 3. 4.
Conclusion: While I would have liked the percent error to be lower than five percent, the total mass of the magnesium burned was so little that any discrepancies majorly afflicted the final product. At 6.7 percent error from the theoretical, we can conclude that Dalton's Law of Proportions holds true. In part two we were to figure out what the molar proportion the H2O to the hydrous Copper sulphate. We did this by evaporating the H2O and recording the difference from mass initial to mass final. We calculated the ratio to be five H2O molecules per single copper sulphate molecule. We demonstrated Dalton's Law of Proportions by first validating it in part one of the experiment and using what we had observed to calculate the number of H2O molecules per copper sulphate.