C512+02->CO2+H2O more than 1 question

Question

How many grams of C5H12 are needed to produce 125 grams of CO2?

how many grams of water can be produced from 15 grams of C5H12 and 20 grams of Oxygen? What is the limiting reactant?

Answer 1

For the first part, (125g CO₂)*(1 mol CO₂ /44.0g CO₂)*(1 mol C₅H₁₂ /5 mol CO₂)*(72.1g C₅H₁₂ /1 mol C₅H₁₂) = 41.0 g C₅H₁₂.

The second part is: With 15g of C₅H₁₂ you would predict (15g C₅H₁₂)*(1 mol C₅H₁₂ /72.1g C₅H₁₂)*(6 mol H₂O /1 mol C₅H₁₂) = 1.25 moles of H₂O.

With 20g of O₂ gas, you would predict (20g O₂)*(1 mol O₂ /32.0g O₂)*(6 mol H₂O /8 mol O₂) = 0.469 mole of H₂O. This is limiting, because when you have made this much water, there is no more oxygen to consume.

Finally, (0.468 mole H₂O)*(18.0g H₂O/1 mol H₂O) = 8.4g H₂O (to 2 sig figs).