In the combustion reaction 2C2H6 + 702 → 4C02 + 6H20, ethane gas reacts with oxygen to produce carbon dioxide and steam. If 18.6 grams of C2H6 reacts with O2, how many moles of
steam does it produce?

1.86moles

Explanation:

Given chemical reaction:

   2C₂H₆  +  7O₂  →  4CO₂  +  6H₂O

Mass of C₂H₆   = 18.6g

Unknown:

Number of moles of steam produced  = ?

Solution:

  2C₂H₆  +  7O₂  →  4CO₂  +  6H₂O

 We have checked and the equation is balanced.

Now, find the number of moles of C₂H₆ from the given mass;

   Number of moles  =  

 Molar mass of C₂H₆ = 2(12) + 6(1) = 30g/mol

  Number of moles  =   = 0.62moles

From the balanced reaction equation:

      2 mole of C₂H₆ will produce 6 moles of steam

     0.62 moles of C₂H₆  will therefore produce   = 1.86moles