Due to intermolecular interactions, the total volume measured
when two real liquids (e.g. ethanol and water) are mixed deviates
from the total volume calculated from the individual volumes of the
two liquids (volume contraction). To describe this non-ideal
behaviour in the mixing phase, one defines partial molar quantities
which are dependent on the composition of the system. The values of
these can be experimentally determined.
- An illustrative fundamental experiment in thermodynamics
- Visualising the difference between ideal and real behavior
- Measure the densities of different ethanol-water mixtures of
specified composition at 20 °C with pycnometers.
- Calculate the real volumes and the mean molar mixing volumes of
the investigated ethanol-water mixtures and also the partial molar
volumes of each liquid for selected compositions.
- Compare them with the molar volumes of the pure substances at
What you can learn about
- Principles of thermodynamics
- Ideal and non-ideal behaviour of gases and liquids
- Volume contraction
- Molar and partial molar quantities
- Precision balance 620g/0.001g