Freezing Various Liquids
Most recent answer: 10/22/2007
- Lavesh Dhanani (age 10)
Panther Run Elementary, Pembroke Pines, FL, Broward
When water freezes, the water molecules arrange themselves into special patterns - this is why we can sometimes see neat patterns in water crystals. If there is something like sugar mixed into the water (an impurity), then it is harder for the water molecules to form the proper patterns. The sugar molecules are not the same shape or size as the water molecules are, so they dont fit into the ice crystals, even though they do fit nicely into the liquid water. Because of this, its actually harder to freeze liquids like juice or soda than plain water - you have to get them colder before they will freeze. This is why these impure liquids did not freeze as quickly as plain water. In chemistry, this is called freezing point depression.
(published on 10/22/2007)
Follow-Up #1: freezing points of liquids
- Jana (age 12)
Before going any further let me say that it sounds like a very bad idea to be using car gasoline. It can catch fire or even explode very easily. It gives off highly toxic fumes. Switch to something else. Some good examples of fluids that are a lot different from the ones you've tested are isopropyl and/or ethanol rubbing alcohol (70% and 90%).
Water, coke, juice etc. are all water with some molecules dissolved in it. The oils don't have water. Their molecules don't have the electrically charged regions that water molecules have, so that takes away one of the main things that helps water molecules stick to each other to make ice. However, the oils are made of fairly long molecules that can still get stuck to each other pretty easily. Gasoline is made of similar types of molecules but much shorter, so they tumble around more easily.
You might want to check this site for more information. You can look in the answers in "melting and freezing" in the "states of matter and energy" category, .
(published on 03/09/2011)