Question

145) 20 ml of a hydro carbon requires 100 ml of oxygen for, complete combustion. In
this reaction 60 ml of carbondioxide is produced. The formula of hydro carbon is
A) C2H4
B) C3H6
C) C3H8
D) C6H6​

Answer 1

Answer:

option no C is correct

Step-by-step explanation:

At STP, 1 mole of any gas occupies 22.4 L.

20 ml of hydrocarbon, 100 ml of oxygen and 60 ml of carbon dioxide corresponds to 0.89, 4.46 and 2.67 moles respectively.

Hence, the combustion of 1 mole of hydrocarbon will require 5 moles of oxygen and will produce 3 moles of carbon dioxide.

Thus, the molecular formula contains 3 carbon atoms.

Out of 5 moles of oxygen, 3 moles will combine with carbon to form 3 moles of carbon dioxide.

The remaining two moles of oxygen will combine with 8 moles of hydrogen atoms (from the hydrocarbon) to form 4 moles of water.

Thus, the molecular formula contains 8 hydrogen atoms.

The hydrocarbon is C3H8 and the combustion reaction is CC3H +5O2 →3CO2 +4H2O.