Volumetric Dilatation of Liquids

The swelling of liquids has some differences in the swelling of solids, starting with their considerably higher swelling coefficients and for the volume of a liquid to be measured, it must be inside a container.

The law governing the expansion of liquids is fundamentally equal to the volumetric expansion of solids, since they cannot dilate linearly or superficially, so:

But since the liquid must be deposited in a solid container, its expansion must also be considered as it occurs simultaneously.

Thus, the actual dilatation of the liquid is the sum of the apparent and container dilations.

To measure apparent dilation, a container filled to the brim is usually used. When heating this system (container + liquid) both will dilate and, as liquids tend to dilate more than solids, a quantity of liquid will be spilled, this amount measures apparent dilation of the liquid.

Like this:

Using the expression of volumetric dilation, , and assuming that the initial volumes of the container and liquid are equal, we can express:

That is, the actual swelling coefficient of a liquid equals the apparent swelling sum with the swelling coefficient of the bottle in which it is located.


(1) A 10dm³ graduated glass is filled with ethyl alcohol, both initially at the same temperature, and heated to 100 ° C. What was the actual dilation of alcohol?