Can anyone please explain Boyles law to me in simple terms?

Question

Im doing an assignment for college on Robert Boyle.. I just cant find a simple explination or definition for his law in terms that I can actually understand..

Boyles law:

"Volume and pressure of an ideal gas held at a constant temperature"

This simply means nothing to me..

Can anyone simplify it into easier words?

Thanks

Answer 1

IF you have a (insulated) steel tank (can't expand or contract) and it has some idea gas inside -- if you add more gas (increase the pressure), the volume is constant (tank can't expand), so the only other thing that can happen is the temperature must go up. Likewise when you let the pressure out, the temperature must go down.

Perhaps you have noticed letting the air out of a tire? It comes out very cold, right? There's your real-life example of Boyles law.

On the other hand, consider a balloon. If you fill it with an ideal gas the pressure increases but, the temperature of the gas remains the same (the balloon doesn't get hot or cold, right?). What has changed: the volume increases.

So, when you increase the pressure of an ideal gas, either the temperature has to go up, or the volume has to go down (or a combination of the two in a proportional fashion).

What makes an ideal gas 'ideal' is that there is a linear relationship between pressure and temperature, and an inverse linear relationship between pressure and volume. The equation is: P*V = k * T
I won't get into what 'k' is here, but it is a constant based on the amount of gas present.

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Answer 2

Wikipedia puts it a bit differently: "For a fixed amount of gas kept at a fixed temperature, P and V are inversely proportional." The simplest illustration is to picture a syringe filled with air. If you push down on the barrel (assume no air escapes) the volume decreases - the air is compacted into a smaller space. Since the air molecules are compacted, they push against each other and against the sides of the syringe, increasing the pressure. And vice versa: pull on the barrel and the air molecules push on each other less, thereby decreasing the pressure. Pressure and volume are inversely proportional, meaning that when one increases the other decreases in the same ratio.
The following is a great animation from NASA:

Answer 3

PV
___ = R

T

T is absolute (deg K)

the equation says if the volume does not change
then if the temperature doubles the volume doubles too

or if the Temperature remains unchanged
then if the volume is halved the pressue doubles

Caution : I recall that as Boyle and Charles Law

Answer 4

As the temperature rises, the volume increases.

Answer 5

pressure is directly proportional to volume at constant temperature. so if you increase the pressure at constant temperature, the volume will also increase.
the formula will be PV (initial condition) = PV (final condition)
P = pressure
V = volume