For ideal gas, there is no attraction between its molecules. But for real gas molecules, there are attractive forces in between molecules. Those are called Van der Waals forces.
To determine which gas particles are more strongly attracted to each other, you can compare two different gases at constant pressure but different temperatures. Because of the Van der Waals forces, the increase in volume due to temperature will be smaller than what is predicted by the ideal gas law. The larger the difference from the ideal gas law's prediction, the larger the intermolecular attractive force is.
Answer:
Explanation:
another way to look at it - for gases within the same group, the larger the attractive force, the closer the gas molecules can get together; i.e. the higher the gas density.
for example, for Group VII Halogens gases, the further down the gas, the higher its gas density: I2 > Br2 > Cl2 > F2. The Van der Waal force is also dependent on the gas masses. That means higher gas density indicates stronger attractive force.
