Iron with a mass of 14 g was fused with 6.4 g of sulfur. Calculate the mass of the unreacted substance.

Iron with sulfur reacts with the formation of iron sulfide FeS. Warming up the mixture is required to start the reaction.

The reaction equation can be written as follows:

Fe + S = FeS

Let us calculate, according to the reaction equation, which starting material was in short supply.

Molar mass of iron = 56 g / mol

Molar mass of sulfur = 32 g / mol.

For the calculation, we take the mass of iron as X.Then we get the proportion:

X g of iron corresponds to 6.4 g of sulfur as

56 g / mol iron corresponds to 32 g / mol sulfur

X = (6.4 * 56) / 32 = 11.2 g of iron is needed for the reaction with 6.4 g of sulfur.

It turns out that sulfur is in short supply. We find the difference between the reacted mass of iron and the existing one.

Y = 14 – 11.2 = 2.8 g iron.

Answer: 2.8 g of iron did not react.