Question

50 POINTS!!!!!!!!!!!

Answer 1

  Cu     + S     =     CuS .

  4 grams of copper = 4 / 63.5 = .0629

2 grams of sulphur = 2 / 32 = .0625  

So .0629 mole of copper reacts with same mole of sulphur

So the reaction is taking place  as follows

Cu     + S     =     CuS .

If copper is increased to 6 grams

6 gm of copper = 6 / 63.5 = .0944 moles of copper

sulphur =  .0625   moles

ratio of moles of copper and sulphur =  .0944 / .0625 = 3 / 2 = 1.5

Another compound may be formed as follows

3 Cu + 2 S = Cu₃ S₂

Compound between copper and sulphur can be formed in many ratios where the ratio of cu and s can vary between .5 to 2 . Hence in this case compound like Cu₃S₂ may be formed.  

Answer 2

The law that the scientist used to predict that the product of the reaction would be 15.9 g of copper sulfate is the law of conservation of matter (mass)

The law of conservation of matter states that matter can neither be created nor destroyed during a chemical reaction but can be transferred from one form to another.

The law above suggest that the total mass of reactants is equal to the total mass of the product i.e

Total mass of reactant = Total mass of product

Considering the question given above, we obtained the following:

Mass of Cu = 12.7 g

Mass of S = 3.2 g

Mass of CuS = 15.9 g

Cu + S —> CuS

Reactant = Cu + S = 12.7 + 3.2 = 15.9 g

Product = CuS = 15.9 g

From the above illustration, we can see that the total mass of the reactants is equal to the total mass of the product.

Therefore, we can conclude that the scientist used the law of conservation of matter to predict the mass of the product.

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