Can you pls Ans//: How would the calculated percent yield of copper in step 41 b

Question

Can you pls Ans//: How would the calculated percent yield of copper in step 41 be affected (too large, too small, no affect) by the following 3 observations? Explain each. a) you did not add enough H2SO4 in step 34 and very little H2 was formed.

b)Although the instructions in step 33 called for "about 0.3 g magnesium turnings", you added o.25 g of magnesium.your original copper wire had a mass of 0.241 g.
c) The filter paper in step 40 still had a strong order of acetone after you weighed the paper and residue. Thanks.

Explanation / Answer

(a): In step -34 the H2SO4 added reacts with excess Mg left to form MgSO4 and H2 gas. If we do not add enough H2SO4, magnesium will remain as impurity and the percent yield will increase.

(b): moles of Cu taken = mass / molar mass = 0.241 g / 63.546 g/mol = 0.003793 mol

moles of Mg taken = mass / molar mass = 0.25 g / 24.30 g/mol = 0.01029 mol

Since the moles of Mg is higher, it will be completely able to displace all the copper. Hence there will be no effect.

(c): Extra mass of acetone will increase the weighted amount of copper leading to an increase in percent yield.

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