The mass of a liter of water can be determined using one of the
described methods for weighing a liquid.
The chosen container must have a capacity of 1 liter but it is also
possible to use a smaller container and use the proportionality between
mass and volume.
In order to obtain the best result, we should use a container with the
most accurate indications of volume. Beakers, flasks and test tubes
have graduations but their accuracy is lower than that of a volumetric
There are different models of volumetric flask: 25, 50, 100, 500 mL and
Models of 1 L remain quite rare but we may measure the mass
of 500 mL of water and multiply the result by 2 to obtain the mass of
1 L (1000 mL) of water.
The measure gives finally this result:
A liter of pure water has a mass of 1 kg
This value is a characteristic of pure water: another pure substance or
a mixture that contains water would have a different mass.
This value has a historical origin: a kilogram was defined as the mass
of a liter of pure water in 1995.