5. Calculate the yield of copper oxide: (a) Expected number of moles of copper o

Question

5. Calculate the yield of copper oxide: (a) Expected number of moles of copper oxide (using the empirical formula of copper oxide and the starting moles of Cu) (b) Actual mass of copper oxide (g) (c) Actual moles of copper oxide (dividing the mass by the MW of the copper oxide)
6. Calculate the percent difference between the expected and actual values for the moles of copper oxide, according to the following equation:
%difference= |expected moles-actual moles| / expected moles *100%
Materials Used -50 mL beaker -balance - 5 g Copper sulfate pentahydrate -30 mL of water -test tube Method 2 1. Place empty beaker on balance and record mass: 85.000 g 2.Take empty beaker off balance, place on lab area and then add 5 g of Copper sulfate pentahydrate 3.Place beaker and copper sulfate pentahydrate unto balance and record mass: 90.00 0 g 4·Dissolve copper sulfate pentahydrate by adding 30 mL of water 5.Then add 10 mL of 6M sodium hydroxide Reaction: Color change from blue to transparent 6. Transfer the liquid content to a new beaker and the hard material in the old beaken 7. Place a test tübe on the balance and record mass: 27.400 g place on top of Bunsen bumer ane then allow to cool on workbench before recording n Place on top of Bunsen burmer and then allow to cool on workbench before recording ew mass: 28.993 g

Explanation / Answer

Solution:

5a) from emiprical formulae we 5 g of Cu is present so moles = 5 / 63.55 = 0.0786

5b) Actual mass of Cu2O is 1.555 g (28.933 - 27.400)

5c) actual moles of Cu2O is (1.555/143.1) = 0.01087

6) %difference= |expected moles-actual moles| / expected moles *100%

= (0.0786 - 0.01087) / 0.786 * 100%

      = 8.617 %

7) yes the difference in yield is observable, as it is caused by combustion druring exposure to bunsen flame, in general heat should be increased gradually for complete combustion if suddenly exposed to high heat then their will always be difference in yield percentile.

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