The general equation for the complete combustion of an alkane is given by . If a pure sample of an u — Hydrocarbons Chemistry Question
Question
The general equation for the complete combustion of an alkane is given by $C_n H_{2n+2} + \frac{3n+1}{2} O_2 \to nCO_2 + (n+1)H_2O$. If a pure sample of an unknown alkane requires exactly 5 moles of $O_2$ per mole of alkane for complete combustion, what is the value of '$n$' (the number of carbon atoms in the alkane)?
Answer: 3
💡 Solution & Explanation
Using the stoichiometry from the general combustion equation, the moles of oxygen required per mole of alkane is equal to $\frac{3n+1}{2}$. Setting this equal to 5: $\frac{3n+1}{2} = 5 \implies 3n+1 = 10 \implies 3n = 9 \implies n = 3$. The alkane is propane ($C_3H_8$).
💬Ask on WhatsApp →
Still have doubts about this question?
Send it to our AI chemistry tutor on WhatsApp — gets answered in minutes