both gases and liquids satisfy the definition of a fluid, waht characteristics distinguish these two states?

Answer 1

Gasses have a weaker attractive force meaning they will diffuse out infinitely through Brownian movement http://en.wikipedia.org/wiki/Brownian_movementhttp://en.wikipedia.org/wiki/Brownian_movement . A liquid on the other hand has a higher attractive force. It will take the shape of its container, but will also clump together. If you spill water it will stay in a puddle instead of diffusing throughout the whole room.

P.S. Guy who answered before me is an idiot, all states of matter are compressible (except solids that were compressed to their limit). Also, guy who answered after me is also wrong (Wikipedia is wrong). If you fill a balloon with helium, helium will take the balloon's shape.

Answer 2

Liquids form a free surface (ie. one that is not defined by their container) whereas gases do not. This is because there are forces holding a fluid together, for example, water molecules (H20) are polar and thus mildly magnetic. Gases do not have the intramolecular forces and thus will happily drift away from each other if given the chance.

dudas_91 is mostly correct; some liquids can be compressed, most fluids will stay in a puddle, although superfluids will flow over obstacles to find a general level. Helium will fill the balloon in it's gaseous state, expanding as far as it can go. However liquid helium will form a surface inside the balloon (unless the balloon is totally filled). For most, gravity confuses the issue, so look to how water and other liquids behave for astronauts while in space. They form a surface. Gases will simply expand.

Answer 3

Gases are compressible and liquids are not.