How many grams of pure iron will be released during aluminothermy 120 grams of three-volume iron oxide?

Solution:
1. It is necessary to draw up the reaction equation:
Fe2O3 + 2Al = Al2O3 + 2Fe – redox reaction, iron is obtained;
2. Let’s define the molar masses of substances:
M (Fe2O3) = 55.8 * 2 +16 * 3 = 159.6 g / mol;
M (Fe) = 55.8 g / mol;
3. Let’s calculate the number of moles of Fe2O3, if the mass is known:
Y (Fe2O3) = m / M = 120 / 159.6 = 0.75 mol;
4. Let’s make a proportion according to the equation data:
0.75 mol (Fe2O3) – X mol (Fe);
-1 mol -2 mol hence, X mol (Fe) = 0.75 * 2/1 = 1.5 mol;
5. Let’s calculate the mass (Fe) by the formula:
m (Fe) = Y * M = 1.5 * 55.8 = 83.7 g.
Answer: the method of aluminothermy obtained iron weighing 83.7 g.