The Lucas Test distinguishes between primary, secondary, and tertiary alcohols using a mixture of concentrated $HCl$ and anhydrous $ZnC{l}_2$.

• The reaction follows an $S_{N}1$ mechanism through a carbocation intermediate.
• Reactivity Order: $3^{\circ }$ (Tertiary) $>2^{\circ }$ (Secondary) $>1^{\circ }$ (Primary).
• Observation:

1. $3^{\circ }$ Alcohols: Form turbidity (alkyl chloride) immediately.
2. $2^{\circ }$ Alcohols: Form turbidity in 5-10 minutes.
3. $1^{\circ }$ Alcohols: Do not produce turbidity at room temperature; reaction occurs only upon heating.