Difference between revisions of "Distillation apparatus"

Revision as of 09:10, 14 November 2015

Distillation is a process of separating the component substances from a liquid mixture by selective evaporation and condensation. A large variety of equipment is utilized to perform distillations in a laboratory setting. In older times, distillation apparatus was connected with rubber stoppers and glass tubes; however, in modern practice, ground glass joints are far more common due to their versatility and ease of use.

Types of Distillation

Simple Distillation

Simple distillation is a process in which vapors from the boiling flask are directly fed into the condenser. This process is primarily used to separate mixtures of liquids with significantly different boiling points.

Fractional Distillation

In fractional distillation, the vapors are fed through a fractionating column before entering the condenser. Cycles of vaporization and condensation within the column improves separation and allows liquids of much closer boiling points to be separated.

Vacuum Distillation

A vacuum distillation is any distillation conducted under reduced pressure. Reducing the pressure lowers the boiling points of the liquids in the mixture, allowing high-boiling mixtures to be easier to separate.

Flasks

Flasks are commonly used for both the boiling vessel and receiver. Several types of flasks are listed below:

Erlenmeyer

Round-bottom

Flat-bottom

Pear-shaped

Miscellaneous

Condensers

Condensers are used to convert gaseous vapor into liquid in a process called condensation.

Liebig

The Liebig condenser is the simplest type of water cooled condenser. It consists of a straight tube as the vapor path which is surrounded by an outer jacket for the coolant path.

Graham

The Graham condenser is a very highly efficient distillation condenser. The vapor path is a tightly coiled tube surrounded by a water jacket, so it acts like a very long Liebig condenser.

Friedrichs

The Friedrichs condenser is a complex type of condenser that is very efficient and can be used for both reflux and distillation. It consists of an internal cold finger that is filled with coolant that has a spiral path shaped into it which the vapor phase flows onto. Condensate flows down this spiral path.

Columns

Columns are used in fractional distillation to aid in the separation of mixtures of liquids with closer boiling points.

Vigreux

A Vigreux column is a glass tube lined with many indentations pointing towards the center. The indentations serve to increase internal surface area, resulting in more efficient vaporization/condensation cycles. This leads to better separations of liquids with closer boiling points.

Hempel

Adapters

Various distillation adapters are used to connect together the rest of the apparatus.

Still head

A still head is a three-way glass adapter. Usually, one tube of the adapter is set pointing downwards at a 75 degree angle relative to vertical. It connects the boiling flask to the condenser, and the third tube is generally used in conjunction with a thermometer to measure the temperature of the vapor.

Vacuum take-off

Claisen

Thermometer adapter

This adapter allows a thermometer to reach into the system while still maintaining an airtight seal.

Miscellaneous

Thermometer

Vacuum Pump