# Can water volume reduce with introduction of another chemical [duplicate]

Can a chemical be introduced to a volume of water which can actually reduce the volume of water in that container?

## 1 Answer

Yes, at least if only the total volume should decrease:

Density of water: $$\pu{1000 kg/m^3}$$
Density of ethanol: $$\pu{789 kg/m^3}$$
Expected density of 52 Vol.% ethanol solution: $$\pu{890 kg/m^3}$$
True density of 52 Vol.% ethanol solution: $$\pu{909 kg/m^3}$$
All values are for the same conditions.

The volume of every ethanol-water solution is smaller than the sum of the original volumes of water and ethanol. For example if you add $$\pu{52 mL}$$ of ethanol to $$\pu{48 mL}$$ water you will get a solution with an volume of approximately $$\pu{97.9 mL}$$.
This effect is known as volume contraction and depends on the mixing ratio of both components in a nonlinear way. Its reason is the formation of additional bonding forces (e.g., hydrogen bridges) between the molecules, which results in a higher density.

Note: I don´t think that there is something that can increase density of water in such a way that the resulting total volume is actually smaller than the volume of water used.