The mass of aluminum, which is required to obtain 39 g of chromium by the aluminothermal

The mass of aluminum, which is required to obtain 39 g of chromium by the aluminothermal method from its oxide, is equal to ..

Let’s implement the solution:
1. Let’s write the equation:
Cr2O3 + 2Al = 2Cr + Al2O3 – OBP, occurs when heated. in industry is called aluminothermy, chromium is obtained;
2. Let’s calculate the molar masses:
M (Al) = 26.98 g / mol;
M (Cr) = 51.9 g / mol.
3. Determine the number of moles of chromium:
Y (Cr) = m / M = 39 / 51.9 = 0.75 mol;
Y (Al) = 0.75 mol since the amount of these substances according to the equation is 2 mol.
4. Find the mass of the metal – Al:
m (Al) = Y * M = 0.75 * 26.98 = 20.235 g.
Answer: corresponds to – a) 20.25 (rounded value).