Calculate the mass of dry residue, as a result of calcining 10 grams of Fe (OH) 3

When calcining iron (III) hydroxide, its thermal decomposition into iron (III) oxide and water will occur. The water will evaporate, in the remainder we get dry Fe2O3 – a red-brown powder.

2 Fe (OH) 3 = Fe2O3 + 3 H2O

Molar mass Fe (OH) 3 = 107 g / mol

Molar mass Fe2O3 = 160 g / mol

Let’s make a proportion according to the reaction equation:

10 g Fe (OH) 3 corresponds to X g Fe2O3 as

2 * 107 g / mol Fe (OH) 3 corresponds to 160 g / mol Fe2O3

X = (10 * 160) / (2 * 107) = 7.48 g.

Answer: the mass of iron (III) oxide = 7.48 g.