Does the density of a substance change when the volume changes?

Answer 1

Yes. Take a standard element, when it's a gas it's got a huge volume, the volume of its container (a gas tends to be defined as when the particle are fully separated from each other, taking up all the space it can.)

A liquid takes up less volume, because all the particles are closer to each other.

And a solid, the particles are fixed and, depending if its nonpolar or polar, the solid takes up slightly less or more volume.

Answer 2

The density of matter does change when the state of matter changes. Most materials are most dense in the solid state and least dense in gaseous state (this is kind of intuitive). Water is an exception, though. It is most dense in the liquid state (at 4 degrees C, to be exact) -- that's why ice floats on water!

Answer 3

For all compounds and elements but H2O, it becomes less dense as it goes from solid to liquid to gas. Water is the exception because of hydrogen bonding, which makes ice less dense than water because ice, in a crystalline structure, has more hydrogen bonds than water does. Also, water is most dense at 4 degrees Celcius, becoming less dense above and below that temperature, for the same reasons. Water vapor (gas) is still less dense than water. So, usually elements and compounds follow the trend in density: solid > liquid > gas and water is: water > ice > water vapor

Answer 4

Yes. If the volume increases, density will decrease. If the volume decreases, density will increase.