Question

Using the Law of Conservation of Matter, determine the number of grams of iron sulfide (FeS) that will be produced in this reaction.

112g Fe + 64g S → _____ g FeS
A) 48 grams
B) 64 grams
C) 112 grams
D) 176 grams

Answer 1

Since it is a synthesis, or combination, reaction where 2 become 1, the mass of the product will be the sum of the masses of the reactants.
112g + 64g = 176g
D) 176 grams

Answer 2

Answer : The correct option is, (D) 176 grams

Solution : Given,

Mass of Fe = 112 g

Mass of S = 64 g

Molar mass of Fe = 56 g/mole

Molar mass of S = 32 g/mole

Molar mass of FeS = 88 g/mole

According to the Law of conservation of matter, in the chemical reaction, the total mass of the products must be equal to the mass of the reactants.

The given balanced chemical reaction is,

`Fe+S\rightarrow FeS`

From the reaction, we conclude that the 1 mole of iron, (Fe) react with the 1 mole of sulfur, (S) to give 1 mole of iron sulfide, (FeS).

First we have to calculate the moles of Fe and S.

`\text{Moles of Fe}=\frac{\text{Mass of Fe}}{\text{Molar mass of Fe}}=(112g)/(56g/mole)=2moles`

`\text{Moles of S}=\frac{\text{Mass of S}}{\text{Molar mass of S}}=(64g)/(32g/mole)=2moles`

The moles of Fe and S are same. From the reaction, we conclude that

As, 1 mole of Fe react to give 1 mole of FeS

So, 2 moles of Fe react to give 2 moles of FeS

Now we have calculate the mass of FeS.

`\text{Mass of FeS}=\text{Moles of FeS}* \text{Molar mass of FeS}=2moles* 88g/mole=176g`

Therefore, the number of grams of iron sulfide (FeS) produced in this reaction will be, 176 grams.