When a hydrocarbon $A$ undergoes complete combustion it requires 11 equivalents of oxygen and produc

Question

When a hydrocarbon $A$ undergoes complete combustion it requires 11 equivalents of oxygen and produces 4 equivalents of water. What is the molecular formula of $A$ ?\

Professor PC Thomas Classes · Answer

(d): Balanced equation for combustion is\ $\mathrm{C}_{x} \mathrm{H}_{y}+\left(x+\frac{y}{4}ight) \mathrm{O}_{2} ightarrow x \mathrm{CO}_{2}+\left(\frac{y}{2}ight) \mathrm{H}_{2} \mathrm{O}$\ Given : Moles of water produced are 4, so\ $\frac{y}{2}=4 \Rightarrow y=8$\ Moles of oxygen used are 11, so\ $x+\frac{y}{4}=11 \Rightarrow x=9$\ Hence, the formula becomes $\mathrm{C}_{9} \mathrm{H}_{8}$.\