| Your Fun Family - Science |
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Lava Lite
Materials you will need:
- A glass jar or clear drinking glass
- Vegetable oil
- Salt
- Water
- Food coloring
Experiment
1. Pour about 3 inches of water into the jar.
2. Pour about 1/3 cup of vegetable oil into the jar. When everything
settles, is the oil on top of the water or underneath it?
3. Add one drop of food coloring to the jar. What happens? Is the
drop in the oil or in the water? Does the color spread?
4. Shake salt on top of the oil while you count slowly to 5.
Wow! What happens to the food coloring? What happens to the salt?
5. Add more salt to keep the action going for as long as you want.
What Happened ?
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. Things that are less dense than water
will float in water. Things that are more dense than water will sink.
Even though oil and water are both liquids, they are what chemists
call immiscible liquids. That's a fancy word that means they don't 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.
How does a real lava lamp work?
Like your oil and water, the "lava" in a Lava Lite doesn't mix with the
liquid that surrounds it. When it's cool, the "lava" is a little bit denser
than the liquid surrounding it. When the "lava" rests on the bottom of
the Lava Lite, the light bulb in the lamp warms it up. As it warms up,
the "lava" expands a little. When it expands, the "lava" stays the same
weight but it takes up more space-so it's less dense. When it's warm
enough, the "lava" is less dense than the surrounding liquid, and so it
rises up to the top to float. At the top of the lamp, it cools down,
becomes more dense, and sinks once again. This cycle repeats over
and over as the "lava" warms up and rises, then cools down and sinks.
1. Pour about 3 inches of water into the jar.
2. Pour about 1/3 cup of vegetable oil into the jar. When everything
settles, is the oil on top of the water or underneath it?
3. Add one drop of food coloring to the jar. What happens? Is the
drop in the oil or in the water? Does the color spread?
4. Shake salt on top of the oil while you count slowly to 5.
Wow! What happens to the food coloring? What happens to the salt?
5. Add more salt to keep the action going for as long as you want.
What Happened ?
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. Things that are less dense than water
will float in water. Things that are more dense than water will sink.
Even though oil and water are both liquids, they are what chemists
call immiscible liquids. That's a fancy word that means they don't 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.
How does a real lava lamp work?
Like your oil and water, the "lava" in a Lava Lite doesn't mix with the
liquid that surrounds it. When it's cool, the "lava" is a little bit denser
than the liquid surrounding it. When the "lava" rests on the bottom of
the Lava Lite, the light bulb in the lamp warms it up. As it warms up,
the "lava" expands a little. When it expands, the "lava" stays the same
weight but it takes up more space-so it's less dense. When it's warm
enough, the "lava" is less dense than the surrounding liquid, and so it
rises up to the top to float. At the top of the lamp, it cools down,
becomes more dense, and sinks once again. This cycle repeats over
and over as the "lava" warms up and rises, then cools down and sinks.
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