Under hood, $40 \;mL$ 2-methylpropan-2-ol (colorless, viscous liquid) are transferred into a separating funnel. We add $120\;mL$ of concentrated hydrochloric acid.
First homogeneous, this mixture quickly becomes cloudy: The product of the reaction, which appears gradually is insoluble.
We close the valve, keep the stopper closed and invert the funnel, we perform tilting movements to mix the reagents. We open the valve time to time to relieve pressure.
2-methylpropan-2-ol is converted to 2-chloro-2-methylpropane:
After 20 minutes, the reaction is complete. The upper phase is decanted.
2-chloro-2-methylpropane is collected and dried over anhydrous calcium chloride and then distilled: It is a colorless liquid.