# Boiling Point

I was thinking tonight about how to get absolutely pure water. The best place to start is to distill water. Boil it, then condense it. Leave the chunks and higher temp boiling liquids behind for distilled water. Someone pointed out before that you can't be sure that distilled water is absolutely pure. Some liquid may boil at a lower point than the water and get distilled right along with the water. Then condense right back in with the water. This can be avoided by boiling the distilled water. If the original water had any liquid in it that boiled hotter than water it would not boil until the water was all gone. If the original had liquid in it that boiled lower than water it would end up in the container with the distilled water. All we have left in the second container is water and liquids that boil at a point lower than water. If we bring the water to a boil we must have removed all of the liquid that would boil at a lower temperature than water because boiling is a constant temperature process. If we have 100C achieved to boil the water then no liquid could be remaining in the water that boiled at lower than 100C. Pure water.

Offered by John.

Which liquids might be contaminating drinking water after the pole shift that boil at a lower temperature than water, and so might still remain in distilled water? I wonder if there are common liquids with low boiling points so that we need to worry about this. If this is true, then we have to be aware of this fact. If the liquids are rare contaminants, then it's less of a concern.

Offered by Craig.

The only liquid I can think of, because I distill it to separate it from water, is alcohol with a boiling point of 180F (if I remember correctly). The easy way to separate lower boiling point liquids from water is to heat the water to just below the boiling point, say, 98C and let it sit at this temp for 10 or 20 minutes open to the air (not connected to the condenser). After 20 minutes or so it should be all gone and the condenser can be connected and the temp raised to 100C. Remember that the boiling point of water (and everything else) decreases with barometric pressure. There are actually a number of liquids that have a lower boiling point than water but I would need a chemistry book to look them up.

Offered by Ron.