Empirical Formula of Copper Sulfate Mass of crucible and cover + copper wire(bef

Question

Empirical Formula of Copper Sulfate

Mass of crucible and cover + copper wire(befrore heating)    41.94 grams

Mass of crucible and cover                                                      40.16 grams

Mass of copper wire                                                                 0.0118

Mass of crucible and cover + copper sulfide(after heating)     35.53 grams

Mass of crucible and cover + copper sulfide(optional second heating) 42.78 grams

Mass of combined heating                                                       45.07 grams

Show the calculation of the Empirical formula.

Explanation / Answer

Answer.

Calculate mass of copper and sulfide:

Mass of copper = (Mass of crucible and cover + copper wire) – (mass of crucible and cover + mass of copper) = 41.94 - (40.16 + 0.0118)

= 1.7682 g of Cu

Mass of sulfide = average(Mass of crucible and cover + mass of copper sulfide) – (mass of crucible and cover - mass of copper) = (35.53+42.78)/2 - (40.16-1.7682)

= 0.7632 g S

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Now we have to calulate moles of Cu and S:

moles Cu = 1.7682 g of Cu x 1 mol Cu/63.55 g Cu

= 0.0278 mol Cu

moles S = 0.7632 g S x 1 mol S/32.07 g S

= 0.0237 mol S

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Empirical formula.

Dividing both moles by smallest one,

Cu = 0.0278/0.0237 = 1.18 = 1

S = 0.0237/0.0237 = 1

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The Empirical Formula of Copper Sulfide is: CuS.

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