What mass of aluminum can be obtained from 16 tons of natural bauxite, the mass fraction of aluminum oxide in which is 75%?

Given: ω (aluminum oxide) = 75%, or 0.75, m (natural bauxite) = 16 tons.
Find: m (aluminum) -?
Decision.
1. Let’s calculate the mass of impurities of aluminum oxide in a sample of natural bauxite:
m (aluminum oxide) = ω (aluminum oxide) • m (natural bauxite) = 0.75 • 16 t = 12 t.
2. Let’s calculate the mass fraction of aluminum in aluminum oxide Al2O3:
Mr (Al2O3) = 2 • Ar (Al) + 3 • Ar (O) = 2 • 27 + 3 • 16 = 102
ω (Al) = 2 • Ar (Al) / Mr (Al2O3) = 2 • 27: 102 = 0.529
3. Calculate the mass of aluminum impurities in the alumina sample:
m (aluminum) = ω (aluminum) • m (aluminum oxide) = 0.529 • 12 t = 6.35 t.
Answer: 6.35 g.