If 7.0 g of C2H6 react with 18 g of O2 how many grams of water will be produced

Answer 1

This is a combustion reaction.

2C₂H₆ + 7O₂ ==> 4CO₂ + 6H₂O ... balanced equation

Next, we find which reactant is limting:

moles C₂H₆ = 7.0 g x 1 mol / 30 g = 0.2333 moles C₂H₆

moles O₂ = 18 g x 1 mol / 32 g = 0.5625 moles O₂

From the balanced equation, we see it takes 7 moles O₂ for 2 moles C₂H₆. Thus, O₂ is limiting.

Now, using the limiting reactant, we determine the theoretical yield of H₂O.

0.5625 moles O₂ x 6 moles H₂O / 7 moles O₂ x 18 g H₂O / mole H₂O = 8.7 g H₂O (2 sig. figs.)