Volume contraction

Generally referred to volume contraction a reduction of the volume. Mostly it is a simple physical process (eg shrinkage during cooling ), refer contraction ( physics ).

In addition, some special phenomena are referred to as the volume contraction, for example, a volume loss during the mixing of certain liquids.

Chemistry

Mixing of liquids

Chemistry called volume contraction ( reduction in volume ) when the mixing of several fluids, the total volume of a solution is less than the sum of the volumes of the individual components. The volume difference is called excess volume and is negative when the volume contraction. It is in many solutions do not exist very low or virtually.

Significantly, however, this effect is in a mixture of alcohol and water. One mixes for example, 48 ml of water with 52 ml of ethanol, the result is a total of 96.3 instead of 100 ml, the reduction of the volume does not depend linearly on the mixing ratio (cf. figure), so the alcohol content of the mixture did not exceed measurements of the volume, can be determined only on those of density or boiling point.

Cause of the volume contraction is the formation of additional binding forces ( formation of hydrogen bonds between the molecules ), so take this for a smaller space. In oceanography, it is a similar, but smaller effect because of the salt content of sea water.

There are also liquids that, when mixed lead to a volume dilatation, ie an increase in volume. In this case, the excess volume is positive.

Impact on salary information

Priority to the content of a component in a solution by volume, so the volume contraction is considered.

If the volume contraction, however, be disregarded, the content is preferably expressed as a volume fraction.

Medicine

The medicine speaks of volume contraction (English volume contraction ) with a reduction in blood volume. Mostly it is due to the general lack of water in the body, see dehydration ( medicine).