Take it further:
What’s going on?
A helpful reminder in chemistry says, “Like dissolves like.” This means that only molecules and compounds with similar properties can dissolve one another. In the case of oil and water, the two liquids do not mix because they are not “like” compounds.Water is polar – each water molecule has a negative end and a positive end. This polarity makes water molecules stick to each other. Oil on the other hand, is nonpolar. There are no negative or positive charges, so water does not stick to oil; it would rather stick to itself. This explains why the oil and water don’t mix, but why does the oil stay on the top of the glass? Oil floats on water because it is less dense than water. Oil is less dense than water because there are fewer oil molecules than water molecules in any given volume. What about the food coloring? The food coloring is water-based, so it does not dissolve in the oil. When we pour the food coloring and the oil into the jar, the food coloring falls through the oil because it is denser. The color drops are also a little bit denser than water because of the color dye molecules, so the drops fall through the water too. But as they fall through the water, they begin to dissolve. This diffuses the drops outward and makes the ‘fireworks” effect.
You will need:
Ice cream ingredients
Take it further:
Where’s the science?
The freezing point of a liquid depends on how many things are dissolved in the liquid. Milk, for example, is water with a bunch of things dissolved or dispersed in it, like fat, sugar, protein, vitamins, and minerals. Milk is actually an emulsion because the fat and protein molecules are suspended in the water instead of dissolved. Your ice cream is an emulsion too! When you add the sugar and vanilla to your milk, you’ve added more things (solutes) to the water (solvent). Adding all of these solutes makes it harder to freeze the solution, so the freezing point goes down. We now have a solution that freezes at a lower temperature than water. How do we get colder than ice?
To get your ice cold enough to freeze your ice cream, we added salt. The salt (solute) dissolves in the water (solvent) and lowers the freezing point of the water, so your ice gets colder and doesn’t melt as fast. The salt and water solution now has a lower freezing point than your ice cream emulsion, which means the ice gets cold enough to freeze your ice cream!
Artists, architects, and engineers all use Pi, which is actually an infinite number (one that has no end) to help them calculate and create perfect circles or curves of specific sizes. This can help in everything from truck wheels to arches in buildings!
For more formulas that use pi, check out: http://www.mathgoodies.com/lessons/vol2/circumference.html
Pi is an infinite number! To see a million digits of pi, visit: http://mathforum.org/library/drmath/view/58312.html
You will need:
|| Test Your Blaster
What is the greatest distance you can be from a target and still hit it with the air?
How could you make a stronger air blaster?
What if you try different sizes of containers?
How about balloons that are stretched more or less taut?
The science that makes this work:
The physics of moving air is called fluid dynamics. Air is a fluid just like liquids. Hitting, tapping, or stretching and releasing the rubber membrane forces a sudden gush of air out the opening. The surrounding air is disturbed forming an invisible swirling and twisting of air similar in shape to a doughnut. Such twisting of air is called a vortex. In fact, some sciene theater performers making these rings of air visible using dry ice or a fog machine.