o A glass jar or glass
o Vegetable Oil
o Food Coloring (optional)
1. Pour about 3 inches of water into the jar
2. Pour about 1/3 cup of vegetable oil into the jar.† When it settles, is the oil on top of the water or underneath?
3. If you want, add a couple drops of food coloring to the jar.† What happens?
4. Shake salt on top of the oil while you count slowly to 5.†
5. Add more salt to keep the action going for as long as possible.
†††††††††††††††††††† Why does the oil float on the water?
†††††† Oil floats on water because a drop of oil is lighter than a drop of water the same size.† Another way of saying this is to say that water is denser than oil.† Density is a measurement of how much a given volume of something weighs.† Thins that are less dense than water will float in it.† Things that are more dense than water will sink.†
Even though oil and water are both liquids, they are what chemists call immiscible liquids.† Thatís a fancy word that means they donít mix.
What happens when I pour salt on the oil?
Salt is heavier than water, so when you pour salt on the oil, it sinks to the bottom of the mixture, carrying a blob of oil with it.† In the water, the salt starts to dissolve.† As it dissolves, the salt releases the oil, which floats back up to the top of the water.