Scout Skills: Desalinization!

If some thirsty chemists lost at sea landed on a deserted island, they could make drinking water by removing the dissolved sea salt from the ocean water. But how? Filtration would not work. The chemists would use the different boiling points of water and salt for separation. Water has a much lower boiling temperature than salt. To understand seperation using boiling points, try this experiment.

Step 1 – With adult help, fill a teakettle half full of water. Add 1/4 cup of salt. Close the top and swirl it to stir. Taste a teaspoonful…yuck!

Step 2 – Fit a bendable straw into the end of another bendable straw. Put one end of the straw through the vent hole on the teakettle. Set the teakettle on the stove, but do not turn on the burner yet.

Step 3 – Use a fork to make a small hole in a disposable aluminum pie pan. Thread the straw through the pie pan hole. Set the pie pan on top of a glass so the straw extends into the glass, but the pie pan does not cover the entire top of the glass.

Step 4 – Fill 3 resealable bags with ice. Set one on the pie pan, wrapping it around the straw. Set the other two ice bags around the outside of the glass.

Step 5 – Turn the burner on high heat until steam appears, them reduce the heat to meduim. When you have collected a large enough sample, taste the water in the glass…Yum! That is distilled water like you can buy bottled and sold at the grocery store.

What happened? Heating the teakettle brought the water to it’s boiling point temerature, where it began to boil – making steam. The steam passed through the straw and was cooled by the ice. The cooled steam condensed, became a liquid, and dripped down into the glass. This is distillation. — The Chemistry Merit Badge Book 2007 printing