By Sean Lancaster, Updated Aug 30, 2022
Concentrating a solution by evaporating solvent is a routine technique in analytical chemistry. A simple distillation setup allows you to precisely remove water, increasing the concentration while maintaining solution integrity.
Apply silicone grease to all joints to ensure a tight seal. Mount the round‑bottom flask on a ring stand using 3‑prong clamps. Attach a Y‑adapter to the flask’s neck and secure it with a rubber stopper. Insert a thermometer through the stopper so the bulb rests in the middle of the side arm. Connect the water condenser to the side arm and attach a vacuum adapter at the condenser’s outlet, directing the drip tube into a graduated cylinder.
Place a few boiling chips into the empty flask to promote even boiling. Fill the flask with the solution to be concentrated, ensuring it does not exceed two‑thirds full.
Start the cold water flow to the condenser. Switch on the heating mantle and raise the temperature gradually to 100 °C, the boiling point of water. Maintain this temperature until the desired volume of water has evaporated. Turn off the heating mantle once the target concentration is achieved.
Allow the drip tube to run to completion, then read the volume of water collected in the graduated cylinder. Use this measurement to calculate the new concentration of your solution.
Secure all glassware with silicone grease and clamps, maintain a steady 100 °C boil, and monitor the collected water to achieve the desired concentration.
Never allow the distilling flask to boil dry; this can damage the apparatus and compromise the solution.
