Question

how many gms water obtained when 30g of C2H6 completely reacts with 500g of O2?

Answer 1

C2H6+7O2-->2CO2+3H2O
This is the required balance chemical reaction required.
Now we have 30g of C2H6 and 500g of O2.
After calculation we find that the limiting reagent in this reaction is C2H6 and hence this will determine the amount of H2O formed.
For 1 mole of C2H6, 3 moles of H2O is formed.
Hence for (30/30)=1 mole of H20 3 miles of H2O if formed.
Weight of H2O formed is (3×18)g=54g