The mass of iron oxide formed by heating 53.5 g of iron hydroxide (3) is …

Based on the data, we write down the equation of the process:
2Fe (OH) 3 = Fe2O3 + 3H2O – decomposition, iron oxide (3) is released;

We make calculations:
M Fe (OH) 3 = 106.8 g / mol;

M (Fe2O3) = 159.6 g / mol;

Y Fe (OH) 3 = m / M = 53.5 / 106.8 = 0.5 mol.

Proportion:
0.5 mol Fe (OH) 3 – X mol (Fe2O3);

-2 mol -1 mol from here, X mol (Fe2O3) = 0.5 * 1/2 = 0.25 mol.

Find the mass of the product:
m (Fe2O3) = Y * M = 0.25 * 159.6 = 39.9 g

Answer: the mass of iron oxide is 39.9 g