Question

Gaseous ethane CH3CH3 will react with gaseous oxygen O2 to produce gaseous carbon dioxide CO2 and gaseous water H2O . Suppose 11. g of ethane is mixed with 56.4 g of oxygen. Calculate the minimum mass of ethane that could be left over by the chemical reaction. Be sure your answer has the correct number of significant digits.

Answer 1

2 C2H6 + 5 O2 -----------------------> 4 CO2 + 6 H2O

60 g            160 g

11.0 g              56.4 g

60g C2H6 ------------------> 160 g O2

x g C2H6 --------------------> 56.4 g O2

x = 60 x 56.4 / 160

x = 21.15 g

actually 21.15 g ethane needed for 56.4 g O2

but we have only 11.0 g ethane . so total ethane will be consumed

mass of ethane left = 0.0 g