Question

26.7g of hidrated compound Fe2O3XH₂O was heated to a Constant mass of 24.0g determing the value of X​

Answer 1

Answer: X = 1

Step-by-step explanation:

We need to determine the number of water molecules in a hydrate. The chemical reaction we write is:

`\text{Fe}_2\text{O}_3 \cdot \text{X} \ \text{H}_2\text{O} \rightarrow \text{Fe}_2\text{O}_3 + \text{X} \ \text{H}_2\text{O}`

From the given information, we started with 26.7 g of hydrated compound, but after heating, were only left with 24.0 g of mass. Since mass is conserved, the missing 2.7 g must belong to the water vapor that evaporated from the compound.

Determining Moles

2.7 g of H2O x 1 mol H2O / (18.016 g H2O) = 0.15 mol H2O

24.0 g of Fe2O3 x 1 mol Fe2O3 / (159.70 g Fe2O3) = 0.15 mol Fe2O3

This means that the number of moles of H2O : number of moles of Fe2O3 is exactly 1 : 1. In other words, the balanced equation must be:

`1\ \text{Fe}_2\text{O}_3 \cdot 1 \ \text{H}_2\text{O} \rightarrow 1\ \text{Fe}_2\text{O}_3 + 1 \ \text{H}_2\text{O}`

So, the value of X = 1.