As a result of the decomposition reaction of iron (III) hydroxide, iron (III) oxide and water are formed.

As a result of the decomposition reaction of iron (III) hydroxide, iron (III) oxide and water are formed. Determine the masses of the reaction products obtained from the decomposition of 100 g of technical iron hydroxide containing 14.4% impurities.

Let’s implement the solution:
1. In accordance with the condition of the problem, we write the equation:
m = 100 g; impurities -14.4%.
2Fe (OH) = Fe2O3 + 3H2O – decomposition occurs when heated, iron oxide (3), water are obtained;
2. Find the mass of Fe2O3, H2O.
3. Calculations:
M Fe (OH) 3 = 106.8 g / mol;
M (Fe2O3) = 159.6 g / mol;
M (H2O) = 18 g / mol;
100 (1- 0.144) = 85.6 g (mass of iron hydroxide without impurities).
4. Determine the amount of the original substance:
Y Fe (OH) 3 = m / M = 85.6 / 106.8 = 0.8 mol.
5. Proportions:
0.8 mol (Fe (OH) 3 – X mol (Fe2O3);
-2 mol -1 mol hence, X mol (Fe2O3) = 0.8 * 1/2 = 0.4 mol;
0.8 mol Fe (OH) 3 – X mol (H2O);
-2 mol – 3 mol from here, X mol (H2O) = 0.8 * 3/2 = 1.2 mol.
6. Find the masses of products:
m (Fe2O3) = Y * M = 0.4 * 159.6 = 63.84 g;
m (H2O) = Y * M = 1.2 * 18 = 21.6 g.
Answer: iron oxide was obtained with a mass of 63.84 g, water – 21.6 g.