Charles's law - Middle School 1st grade - 2nd semester

한글

Charles's law, otherwise known as Charles and Gay-Lussac's law. It's meaning in dictionary means the gas volume gets 1/273 bigger as temperature gets 1℃ higher. Easily, as temperature rise, molecular motion gets active, so volume gets bigger. But, we say 1/273 in accurate number. Using Charles's law, we can put a crushed ping-pong ball back into its original state. Let's look at an example.

<other examples using Charles's law>
Why does a snack pack inflate in hot summer? Let's investigate about the reasons why.

In a snack pack, there is gas called 'Nitrogen'. Before that, why is this 'Nitrogen' inside the pack, instead of oxygen?

You might have seen iron go rusty, or wine get all sour. This situation is called "oxidation response". Like this, if oxidation response happens, the material's properties change. Snacks are mostly food deep-fried so it go bad easily, but nitrogen help reduce chemical reaction and help save snacks. Anyway, when you look at the meaning of Charles's law, you can see that it says 'regardless of kind'. Therefore, the snack pack filled with nitrogen inflates because it's summer and temperature rise. Outside of that, if you put a rubber balloon in hot water, it gets bigger and when you heat air in a hot-air balloon, it floats. These are all connected to Charles's law.

<Let's do a experiment together!>
A good experiment to understand Charles's law is peeing doll experiment.

<Supplies>
a peeing doll, cold & hot water, a tank to get water.
*It's better if the cold and hot water's temperature's gap is large.

First, put the doll in hot water to get rid of air inside the doll. Then, put the doll inside the cold water. Lastly, put the doll in the tank and pour hot water over its head.

Let's talk about the scientific knowledge we can learn through this experiment. First, if you put the doll in hot water, temperature will rise and gas volume will get bigger. Next, when you put the doll  in the cold water, the doll's inside pressure gets weak, so water can get in the doll. Lastly, when you pour hot water back on the doll, the inside pressure gets higher, and water comes out from the doll.

→ When the temperature is low, gas volume decrease, and when the temperature rise, gas volume increases.