After performing an experiment on the formula weight of a copper compound: 1)Wha

Question

After performing an experiment on the formula weight of a copper compound:

1)What would the effect have been on the calculated weight of your unknown as compared to the true formula mass if the solution had been blue green when you filtered you product? Too high, Too Low, or Unchanged (Explain)

2)What would the effect have been on the calculated weight of your unknown as compared to the true formula mass if the solution had not quit bubbling when you filtered your product? Too high, Too Low, or Unchanged (Explain)

3)From your moles of unknown copper metal (.00400 mol) calculate the mass of Mg turnings needed to reduce the copper ions to copper metal. Report your answer in grams and assume no side reactions.

Explanation / Answer

1)

if soltution is blue-green, this means there is still copper i solution, that not everything is in the precipitate You will have a less amount of mass, therefore, expect it too low

2)

Bubbling may be formation of H2, this means that there is still a reaction ocurring If you do not wait for the reaction to bubble, do not expect to have all the precipitate/reactant. Expect a low result

3)

N = 0.004 ml of Cu

Mg(s) --> Mg+2 + 2e

Cu+2 + 2e- ---> Cu(s)

1 mol of Mg per 1 mol of Cu

0.004 mol of Cu therefore you need 0.004 mol of Mg

MW of Mg = 24.305 g/mol

mass = mol*MW = 24.305 *0.004 = 0.09722 g

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