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 $A$?
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 $A$?
Show Hint
- $C _{11} H _8$
- $C _{11} H _4$
- $C _5 H _8$
- $C _9 H _8$
The Correct Option is D
Approach Solution - 1
Hydrocarbon will be
So, the correct option is (D): \(C_9H_8\)
Approach Solution -2
Let the molecular formula of the hydrocarbon be \( C_xH_y \). The balanced combustion reaction is:
\[ C_xH_y + \left( \frac{x + \frac{y}{4}}{2} \right) O_2 \rightarrow x \, CO_2 + \frac{y}{2} \, H_2O \]
We are given that 11 equivalents of oxygen are required, and 4 equivalents of water are produced. Using stoichiometry:
\[ \frac{y}{2} = 4 \quad \Rightarrow \quad y = 8 \]
Substituting in the oxygen requirement:
\[ x + \frac{8}{4} = 11 \quad \Rightarrow \quad x + 2 = 22 \quad \Rightarrow \quad x = 9 \]
Thus, the molecular formula is \( C_9H_8 \).
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(B) Chemical Classification:
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