How dose osmosis work

[tylerbrowner]

This docent make sense to me. Lets say that you had a tub of salt water it the middle of the tub there's a divider. On one side of the tub theirs more salt than the other. If you remove the divider the salt would move around until there's the same amount of salt everywhere. Why is this. Why dose hot air rises i know its less dense because heat expands but how dose that have anything to do with it rising. Dose it weigh less because its less dense than cold air.

[Strange]

This docent make sense to me. Lets say that you had a tub of salt water it the middle of the tub there's a divider. On one side of the tub theirs more salt than the other. If you remove the divider the salt would move around until there's the same amount of salt everywhere. Why is this.

 

That isn't osmosis, but diffusion. It happens because all the molecules (water and salt) are moving around at random. So after some time, it all averages out. Put a drop of ink in a glass of water and watch it slowly spread out until it disappears. Same thing.

 

Why dose hot air rises i know its less dense because heat expands but how dose that have anything to do with it rising. Dose it weigh less because its less dense than cold air.

 

Yes, because it weighs less. (That is what "less dense" means, effectively). It is like oil on water: the oil is less dense and so it floats.

[swansont]

The underlying concept here is energy; systems tend toward their lowest energy state.

[derek w]

The underlying concept here is energy; systems tend toward their lowest energy state.

kinetic energy of individual molecules.

[swansont]

kinetic energy of individual molecules.

 

Sorry, I'm not sure of your point — what about KE of individual molecules?

[Essay]

The underlying concept here is energy; systems tend toward their lowest energy state.

...and systems also tend towards their highest entropy state.

 

Diffusion is a good example of that, it seems to me.

 

~

Edited October 3, 2014 by Essay

[derek w]

 

Sorry, I'm not sure of your point — what about KE of individual molecules?

It's the kinetic energy of the random motion of the water molecules,because there are more water molecules in the low concentrate side of the membrane than on the high side,the sum of the kinetic energy is greater on the low side.

[/backslash/]

Hot air rises above cold air because it is less dense. The particles in the warmer air have more random kinetic energy than those of the cooler air, so they spread out more(kind of like diffusion, explained above). Less dense means that there are less air molecules per cubic unit of space.