Empirical Formulas When copper metal is heated in a crucible with sulfur, a sulf

Question

Empirical Formulas When copper metal is heated in a crucible with sulfur, a sulfur of copper is formed. Identify the copper metal is heated in of copper answer. Use the experimental data to justify your answer. Known copper sulfides are: CuS, Cu_2S, and Cu_2S_5. a. What is the number of moles of copper in the experiment? b. What is the number of moles of sulfur incorporated into the product? c. Based upon your calculations, what is the formula and systematic name of the iron oxide product produced? d. How do you know that the experiment is complete?

Explanation / Answer

a)

moles of coppe rin experiment

mol of Cu = mass of Cu / MW of Cu

mass of Cu = mass of copper wire + cruicible - mass of cruicible = (46.1928-44.8050) = 1.3878 g of copper

mol of Cu = mass/MW = 1.3878/63.546 = 0.02183 mol of Cu

b)

moles of S in product:

assume last heating of sulfur is correct

mass of S = (mass after third heating) - ( mas of cruicible + copper)

mass of S = (46.5430 - 46.1928) = 0.3502 g of S added

mol of S = mass/MW = 0.3502/32.066 = 0.0109212 mol of S

ratio

0.0109212/0.02183 = 0.5

added --< 0.5 mol of S per 1 mol of Cu

c)

so..

Cu2S --> Copper (I) Sulfide

d)

We know its complete when no more change in mass of product + Sulfur is seen, i.e. 46.5429 vs 46.5430 g of final mass is a good statement that experimetn is over, that is, no more S will be added

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