Reaction equation: Si + O2 = SiO2
Since silicon contains 5% of impurities, the pure substance in it is 95%. Let us find the mass of the substance silicon m in-va = w * m solution = 0.95 * 73.7 g = 70.015 g – pure silicon substance. Let’s find its amount n = m / M = 70.015 g / 28 g / mol = 2.5 mol. According to the reaction, 1 mol of silicon is formed from 1 mol of oxide, n (Si) = n (SiO2) = 2.5 mol. Then the mass of the oxide will be m = n * M = 2.5 mol * (28 + 16 * 2) g / mol = 150 g (M is the molar mass, determined from the periodic table).
Answer: 150 g.
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