Calculate the mass of aluminum required to obtain 130 g of chromium from its oxide cr203 by the aluminothermal method.
1. The alumothermal method for the reduction of chromium from its oxide is described by the equation:
2Al + Cr2O3 = 2Cr + Al2O3;
2.Calculate the chemical amount of chromium:
n (Cr) = m (Cr): M (Cr) = 130: 52 = 2.5 mol;
2. since aluminum and chromium have the same valence, then the number of their atoms in oxides is the same and, accordingly, their numbers are equal:
n (Al) = n (Cr) = 2.5 mol;
3. find the mass of aluminum:
m (Al) = n (Al) * M (Al) = 2.5 * 27 = 67.5 g.
Answer: 67.5 g.
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