How many molecules of oxygen are needed to react with 8.87 grams of C3H8?

Answer 1

Hello Nancy

Use stoichiometry to convert grams of C₃H₈ to moles of O₂. Then use avogadro's number to convert moles of O₂ to molecules of O₂. Let's first write the balanced chemical reaction.

C₃H₈ + 5 O₂ → 3 CO₂ + 4 H₂O

Molar mass of C₃H₈ is 44.10 g/mol, and the mole ratio of C₃H₈ to O₂ is 1:5.

8.87 g C₃H₈ x (1 mol C₃H₈ / 44.10 g C₃H₈) x (5 mol O₂ / 1 mol C₃H₈) = 1.01 mol O₂

1.01 mol O₂ x (6.02 x 10²³ molecules O₂ / 1 mol O₂) = 6.08 x 10²³ molecules O₂