A 7.300 gram sample of aluminum was quantitatively combined with a sample of selenium to form a compound. The compound had a mass of 39.35 grams. What is the empirical formula for the compound?

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Quizplus · Accepted Answer

The mass of selenium in the compound is 39.35 g - 7.300 g = 32.05 g. The molar mass of Al is 26.98 g/mol, and Se is 78.96 g/mol. Moles of Al = 7.300 g / 26.98 g/mol = 0.2706 mol. Moles of Se = 32.05 g / 78.96 g/mol = 0.4059 mol. The ratio of Al to Se is approximately 2:3, giving the empirical formula Al₂Se₃.

A 7300 Gram Sample of Aluminum Was Quantitatively Combined with a a Sample