Calculate the mass of iron (III) oxide, which is formed during the decomposition of 20 g of the corresponding hydroxide.

Let’s implement the solution:
1. By condition, we write down the equation of the process:
2Fe (OH) 3 = Fe2O3 + 3H2O – decomposition of hydroxide occurs when heated, iron oxide is released (3);
2. Calculations:
M Fe (OH) 3 = 106.8 g / mol.
M (Fe2O3) = 159.6 g / mol.
3. Determine Y (number of moles) of the initial substance, if the mass is known:
Y Fe (OH) 3 = m / M = 20 / 106.8 = 0.18 mol.
4. Proportion:
0.18 mol Fe (OH) 3 – X mol (Fe2O3);
-2 mol -1 mol from here, X mol (Fe2O3) = 0.18 * 1/2 = 0.09 mol.
5. Find the mass of the product:
m (Fe2O3) = Y * M = 0.09 * 159.6 = 14.36 g.
Answer: Received iron oxide (3) weighing 14.36 g.