Gaseous ethane reacts with gaseous oxygen gas to produce gaseous carbon dioxide and gaseous water. What is the theoretical yield of water formed from the reaction of of ethane and of oxygen gas? Be sure your answer has the correct number of significant digits in it.

1) Write the balanced equation:

2C2H6 + 7O2 - --> 4CO2 + 6H2O

2) Determine limiting reagent:

C2H6 ⇒ 13.8 g / 30.0694 g/mol = 0.45894 mol

O2 ⇒ 45.8 g / 31.9988 g/mol = 1.4313 mol

C2H6 ⇒ 0.45894 / 2 = 0.22947

O2 ⇒ 1.4313 / 7 = 0.20447

Oxygen is limiting.

3) Determine theoretical yield of water:

The oxygen : water molar ratio is 7 : 6

7 is to 6 as 1.4313 mol is to x

x = 1.2268286 mol of water

4) Convert moles of water to grams:

1.2268286 mol times 18.015 g/mol = 22.1 g (to three sig figs)

Solution to (b):

14.2 g / 22.1 g = 64.2%