2 C2H4O + 5 O2 ------------> 4 CO2 + 4 H2O

Question

 2 C₂H₄O + 5 O₂ ------------> 4 CO₂ + 4 H₂O 

 

How many grams of O₂ are required to produce 25.0 g of H₂O?

Answer 1

We start with 25.0g H₂O and convert grams of water to moles of water using the molar mass of water.

25.0g H₂O * (1 mol H₂O/18.02 g H₂O)

Then we use the coefficients of the chemical equation to convert moles of water to moles of oxygen gas.

25.0g H₂O * (1 mol H₂O/18.02 g H₂O) * (5 mol O₂/4 mol H₂O)

Then we convert the moles of oxygen gas to grams of oxygen gas using the molar mass of oxygen gas.

25.0g H₂O * (1 mol H₂O/18.02 g H₂O) * (5 mol O₂/4 mol H₂O) * ( 32.0 g O₂/ 1 mol O₂)

Multiplying everything out (including the units), we arrive at 55.5 g O₂.