Question

Liquid hexane CH3CH24CH3 will react with gaseous oxygen O2 to produce gaseous carbon dioxide CO2 and gaseous water H2O . Suppose 6.0 g of hexane is mixed with 15.1 g of oxygen. Calculate the maximum mass of water that could be produced by the chemical reaction. Be sure your answer has the correct number of significant digits.

Answer 1

CH3CH24CH3 + O2 = CO2 + H2

m = 6 g

mol of Hex= mass/MW = 6/86.18 = 0.0696 mol of hexane

mol of O2 = mass/MW = 15.1/32 = 0.471875 ml

ratio is:

CH3(CH2)4CH3 + O2 = CO2 + H2O

C6H14 +  O2 = CO2 + H2O

C6H14 + 9.5O2 = 6CO2 + 7H2O

0.0696 mol of hexane reuqires --> (9.5) * 0.0696 = 0.6612 mol of O2

we only have

0.471875 mol of O2

so

9.5 mol of hexane = 7 mol of H2O

0.471875 mol of O2 --> 7/9*0.471875 = 0.3670 mol of water

mass = mol*MW = 0.3670*18 = 6.606 g of H2O max

correct sig fig --> 2 --< 6.606 g --> 6.6 g of H2O