Distillation Techniques for Separating Liquid Mixtures

Introduction

Purpose: Separating a liquid from a solution.
- Example: Separating pure water from seawater.
Equipment:
- Flask containing the solution.
- Bung to seal the flask and prevent gas escape.
- Thermometer inserted through the bung.
- Condenser with a water jacket for cooling.
- Beaker for collecting the distilled liquid.
- Heating device (e.g., Bunsen burner).
Process:
- Heat the mixture to evaporate the desired liquid.
- Evaporated liquid rises, gets condensed by the water jacket.
- Collect the condensed pure liquid in a beaker.
- Example outcome: Pure water collected, salt left in flask.
Limitation:
- Ineffective for mixtures with liquids of similar boiling points.

Purpose: Separating mixtures of liquids, especially those with similar boiling points.
Equipment Similarities: Similar to simple distillation with additional components.
Fractionating Column:
- Filled with glass rods, providing high surface area.
- Temperature gradient: Cooler at the top.
Process:
- Example mixture: Methanol, ethanol, propanol.
- Methanol separation:
  - Heat mixture to ~65°C.
  - Methanol evaporates first, rises through fractionating column, condenses, and is collected.
- Other liquids like ethanol and propanol condense back on glass rods due to cooler temperatures and fall back.
Subsequent Separations:
- Increase temperature to ~78°C for ethanol.
- Remaining liquid assumed to be propanol or further separated by increasing the temperature again.

Simple distillation is effective for separating distinct liquid from a solution.
Fractional distillation is essential for separating mixtures of liquids with similar boiling points.
Visualization: Methanol, ethanol, propanol (using colors for illustration in the video).