Question

What is molecular formula of cyclohexylamine?

• A. $C_{6}H_{8}N$
• B. $C_{6}H_{10}N$
• C. $C_{6}H_{12}N$
• D. $C_{6}H_{13}N$

Hint:

To find the molecular formula of a substituted cycloalkane, start with the base cycloalkane formula ($C_{n}H_{2n}$). For each substituent, subtract one hydrogen from the ring and add the atoms of the substituent. For cyclohexylamine, it's $C_{6}H_{12} - H + NH_{2} = C_{6}H_{11}NH_{2}$, which simplifies to $C_{6}H_{13}N$.

Answer 1

The Correct Option is D

Step 1: Understand the structure of cyclohexylamine\nCyclohexylamine is an organic compound consisting of a cyclohexane ring to which an amine $(-\text{NH}_{2})$ group is attached. A cyclohexane ring is a saturated six-membered carbon ring.
Step 2: Determine the molecular formula of cyclohexane\nA cyclohexane ring has the molecular formula $C_{6}H_{12}$. This is derived from the general formula for a cycloalkane, $C_{n}H_{2n}$, where $n=6$.
Step 3: Account for the amine substitution\nWhen an amine group $(-\text{NH}_{2})$ replaces one hydrogen atom on the cyclohexane ring, the formula changes from $C_{6}H_{12}$ to $C_{6}H_{11}(-\text{NH}_{2})$.
Step 4: Combine atoms to find the overall molecular formula\nCounting the atoms:

• Carbon (C): 6 atoms
• Hydrogen (H): 11 atoms from the cyclohexane ring + 2 atoms from the amine group = $11 + 2 = 13$ atoms
• Nitrogen (N): 1 atom\n

Therefore, the molecular formula for cyclohexylamine is $C_{6}H_{13}N$.