Karlos wrote:
GadgetMaster wrote:
Does a certain amout evaporate during the mixing process?
It could, but even assuming you did it in a closed container, the result would be less than 100ml ;-)
Basically, all substances comprise of a certain amount of empty space (in strict terms, the vast majority is empty space but here were talking about intermolecular distances).
If you dissolve a certain volume of salt in water, there's no appreciable change in volume of the water. The dissociated ions are free to roam around the spaces between the H20 molecules (a very simplified picture there, but that's the gist). Overall, the volume has gotten less (ie the volume occupied by the salt has been lost), but the mass has stayed the same, ie, the liquid is denser.
When you mix water and alcohol, each one effectively partially "dissolves" into the other, resulting in a decrease in overall volume. As expected, mass is conserved, so a 50/50 mix is naturally more dense than pure alcohol, but less dense than the pure water.
To summarise it, you always observe conservation of mass, but conservation of volume is, in fact, rarely guarenteed (at least for liquids and solids - gases have their own rules)
