[sand500]

This was interesting so I looked it up

>For a given ideal gas the molecular composition is fixed, and thus the speed of sound depends only on its temperature. At a constant temperature, the gas pressure has no effect on the speed of sound, since the density will increase, and since pressure and density (also proportional to pressure) have equal but opposite effects on the speed of sound, and the two contributions cancel out exactly.

https://en.m.wikipedia.org/wiki/Speed_of_sound#Dependence_on...

[bongodongobob]

I never knew this either. This makes sense as when you tap on a propane tank they always sound empty, different than a metal tank of water. Even though it's a liquid and under extreme pressure, it's only the temperature that matters.

[thfuran]

Liquid propane is definitely not an ideal gas.

[bongodongobob]

Not saying it is, but it's very volatile. It really doesn't want to be a liquid at room temperature. I can't tell if it's empty or full when a tap on it, but definitely can with with water. It's an impedance thing.

[thfuran]

I'm just saying a fact about ideal gases doesn't really imply anything about LP.

[bongodongobob]

It does, vapor pressure.

[nautilius]

That's got nothing to do with some fluid behaving like an ideal gas or not. Also, except for very low pressures, vapor does not behave like an ideal gas.

[jldl805]

That's because propane tanks are only 1/4 full even when filled to max capacity.