Distillation is the process in which a mixture is boiled and the vapour condensed and gathered in order to separate the substances in the original mixture. It is commonly used to purify water because water vapour cannot carry most of the impurities that liquid water may contain. These simple experiments will help children observe the way distillation works and the effects it has.
Basic distillation setup
This basic set-up will be used in all of the experiments below. Attach a clamp to each of two ring stands. Carefully put the sidearm of a distilling flask into a one-hole stopper, plug the top of the flask with a stopper, and place the flask in one clamp with a Bunsen burner beneath it. Attach a Liebig condenser to the second clamp and insert the stopper on the flask's sidearm into the condenser. Attach rubber tubing to the top and bottom sidearms of the condenser, placing the lower tube over a water nozzle and the upper into the sink to drain. Place a beaker under the condenser's spout to collect the distillate.
Dirty water purification
Mix a small quantity of soil into water to make dirty water or, for a more dramatic experiment, use wet mud. Pour the dirty water into the distillation flask, set up the distillation equipment as described, and begin applying heat to the bottom of the flask and running cold tap water through the condenser. As the dirty water comes to a boil, the steam should pass through the sidearm of the flask, turn back into liquid as it passes through the condenser, and drip out into the beaker as clean water.
Flavour of distilled water
This experiment will help children understand the effects of water distillation. Arrange a simple distillation set-up with salt water in the flask. Let each child taste the salt water. Turn on the heat and run cool water through the condenser to distil the salt water. Gather the distilled water and let children try it. Discuss why the water tastes different and help the children observe that the salt remained in the flask.
Distilling different liquids
If you have the equipment, put together a few distillation setups at once. Use them to distil a variety of liquids, such as vinegar, salt water, apple juice and mud. Let children guess the results of each distillation, then examine the distillates to find what stayed in the liquid and what got distilled out. Note that leaving fruit juices or other sugary liquids over a burner for too long will create a carbon deposit in the flask that you may not be able to remove.