Refer to the following balance equation : 2c2h6 + 7o2 = 4co2 + 6 h20. how many moles of c2h6 will combust completely with 2.0 moles of oxygen gas. how many grams of water will be produced when 30.0 g of c2h6 reacts completely with oxygen?

1. From the balanced equation given above, the ratio of the number of moles of the hydrocarbon and oxygen is equal to 2/7. Given that there are 2 moles of oxygen,

    moles hydrocarbon = (2 moles O2)(2 moles HC / 7 moles oxygen)

Simplifying,
   moles HC = 4/7 or 0.57 moles HC

0.57 moles HC

2. The calculation for the mass of water is shown below with the dimensional analysis and conversion factors,

  (30 g C2H6)1 mole C2H6/30 g C2H6)(6 molesH2O/2 moles C2H6)(18 g H2O/1 mole C2H6)

Simplifying,
     mass  = 54 grams of water