Is it more common for a substance to weigh more in its liquid form then its solid form?

Answer 1

The mass is identical, although the density is much lower because the volume it takes up is much greater.
The weight of something is not the same as its mass however. Mass measures the quantity of stuff, to put it in technical terms. Weight is a force, and it is the mass times the force of gravity. So your weight on the moon is different than your weight on earth, but you mass is always the same (unless you diet...).

So if weight is mass * gravity, and since the mass of the gas particles are unchanged going from liquid to gas, and we haven't changed the force of gravity, than the weight is also unchanged.

This question has got me thinking... a lot! Humm... maybe this is why I don't worry about "weight" and stick with "mass" where things are much more clear! Check out the link under "Web Links" about the weight of clouds. It basically says that something that is more buoyant than air can't be weighed, but its weight is still significant. Weird!
I had another thought about this... I think what's confusing is the idea that the gas molecules "floating" in a container don't contribute to the weight of the container, since they are not applying any force downwards, whereas as a liquid, all the molecules are sitting in the bottom of the container, thus contributing to the weight. In fact, some gas molecules are push up by hitting the top of the container! Here is thing: the average speed of gas molecules is much higher than in a liquid. All the gas molecules are moving very fast, but they are moving in all directions equally. So although there are molecules hitting the top of the container, thus reducing the weight of the container with the upward force, there is an equal number pushing hard down! And because of the force of gravity, they are pushing down just a bit harder than the others are pushing up, and so the end effect is the same as the liquid. In the liquid there is less force due to molecules pushing up, but the molecules pushing down are also not moving as fast, and so don't push down as much.
The difference between liquids and gases is the interactions between molecules. Liquids have stronger interactions between adjacent molecules than gases do. However, the interaction with gravity is unchanged, and so the weight is unchanged.

Answer 2

Usually the substance is heavier when it is a solid as there are more particles and they are closer together whereas in a liquid there are less particles as they are further apart!

I THINK! (\___/)

(= 'o'=) I hope that helped ('')('') :0)

An example of a solid being lighter than a liquid is a foam-based solid (kinda like Styrofoam). Since it naturally has air/gaps between the molecules, the liquid form would be heavier since it wouldn't have these "gaps".

Answer 3

The molar mass of a molecule not depends on the phase of matter.

Answer 4

Yes, the gas phase has a much lower density than the liquid phase.