15. A 15.30 g sample of calcium (Ca) combines with 7.96 g of sulfur(S) to form calcium sulfide (Cas). How many grams of CaS are formed?

17.689g

Explanation:

1: First, write out the equation you will follow:

Ca + S ⇒ CaS

2: Use the formula Mass = Mr x moles to work out the moles of both Ca and S - this will enable you to find the limiting reactant.

3: Moles Ca:

Moles = mass/ Mr = 15.3/ 40.1 = 0.382 moles.

4: Moles S:

Moles = mass/ Mr = 7.96/ 32.1 = 0.245 moles.

5: We now know S is the limiting reactant, and as there is a 1:1 ratio between S and CaS, there will also be 0.245 moles CaS.

6: Mass CaS:

Mass = Mr x moles = 72.2 x 0.245 = 17.689g

no

explanation:

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