[NelsonW]

Please help identify this reaction - not for any particular reason other than my own curiosity.
This was demonstrated by my univ. analytical chemistry professor 30 years ago but I have forgotten the reactants:  He had two transparently clear liquids in a two graduated containers, both reactants had the visual appearance of water, and when he combined them, the resulting mixture or compound or whatever had a volume less than the volume of the reactants - a little less.  For example 500 mL of reactant A plus 500 mL of reactant B = 950 mL compound C.  Anyway does anyone know this particular experiment?  What is going on here?  The reaction wasn't exothermic or anything.

[Borek]

No reaction, just volumes are not additive.

Most likely it was pure ethanol and pure water, when combining 500 mL of each you will get 964 mL of the mixture.

While this is not a perfect analogy, it will give you some ideas about what is happening. Imagine combining 500 mL of marbles with 500 mL of sand. Will the final volume be 1 L?

[NelsonW]

OK Thank you for your help.

[Corribus]

While this is not a perfect analogy, it will give you some ideas about what is happening. Imagine combining 500 mL of marbles with 500 mL of sand. Will the final volume be 1 L?

Depends on what order you add them to your container.