atom and molecule

Question

An experiment requires that enough C₃H₈O₃ be used to yield 15.5 g of oxygen.

How much C₃H₈O₃ must be weighed out

Answer 1

When the question asks for a yield of oxygen, it isn't clear if they are referring to elemental oxygen (O), or oxygen gas (O₂). Since C₃H₈O₃ would generate oxygen gas (O₂), we will answer the question that way. We will assume that it takes 2 mols C₃H₈O₃ (6 mol O) to yield 3 mols O₂ (6 mols O)

Molar mass C₃H₈O₃ = 92.1 g / mol

Molar mass O₂ = 32.0 g / mol

Using dimensional analysis:

15.5 g O₂ x 1 mol O₂ / 32 g x 2 mol C₃H₈O₃ / 3 mol O₂ x 92.1 g C₃H₈O₃ / mol = 29.7 g C₃H₈O₃