[Magic_Doctor]

Hello everyone,

First excuse my poor English.

Not being a chemist for a penny, my questions will perhaps seem naive, but I still poses!

When we mixture 2 distinct liquids, contrast to the masses, the volumes are not necessarily additive.
1 L ethanol + 1 L = 1.98 L water mixture instead of "normal" 2 L
A bit like if the mixture was "contracted".

The main reason, it seems, of forces acting on a molecular scale.

1 / What are those forces or phenomena?
2 / How to call it?
3 / Can you calculate them and, depending on the liquids in presence, provide for the "contraction fluid?

4 / There would be situations where the mixing of 2 distinct liquids give an amount greater than the total volume of each liquid. Instead of a "contraction" it would be a kind of "expansion" ... ?
1 L of A + B 1 L = 2.15 L (eg.) Mixing

A very big thank you to light my lantern!

[Borek]

You don't neeed any forces between molecules to observe volume contraction. Mix 1L of marbles with 1L of sand.

[nj_bartel]

He's trying to get you to picture it on a macromolecular scale.

You have 3 substances -
   a) sand
   b) marbles
   c) ping pong balls

Pretend marbles are what make up your initial liquid.  When you add sand to make a sand in marble solution, the sand, due to it's small size, is able to work its way into the empty space between the marbles, resulting in almost no change in volume.  When you add ping pong balls to make a ping pong ball in marble solution, the marbles and ping pong balls, both being rather large, are unable to cram into all the empty air space, and the volume increases.