I think a Van der Waals interaction is dominant for fluids. These subsist well

for a laminar flow, but some break may occur in turbulance.

For fluids the effect is obviously attractive between molecules. A parabolic model potential

works for the ideal distance between molecules, prevents them getting away

or getting too close. This interaction is weak compared to the covalent bond in solids.

For gases the interactions are weak , repulsive if molecules are very close.

The ideal gas model is the first approximation in this case. The next includes the short range repulsion.

Dr Juan Weisz thank you for your contribution to the discussion

If the molecules have similar molar masses and similar types of intermolecular forces, look for the one that is the most polar or that has the most electronegative atoms or the most hydrogen bonding groups. That one will have the strongest IMF's overall. The force of attraction that is present between the molecules of a substance that are held together is known as the intermolecular force of attraction. The intermolecular force is the strongest in solids. The intermolecular force of attraction in liquids is not so strong as in solids. Stronger intermolecular forces → molecules are more attracted to each other → they stick together better → they are harder to separate from each other. Strong IMF's lead to high boiling points, low vapor pressures, and high heats of vaporization. There are three types of intermolecular forces: London dispersion forces (LDF), dipole- dipole interactions, and hydrogen bonding. Molecules can have any mix of these three kinds of intermolecular forces, but all substances at least have LDF. Higher the intermolecular forces, higher will be the viscosity. When there is a strong intermolecular force, the molecules of the liquids are strongly bonded to each other. This induces a resistance to move. The liquids whose molecules are polar or capable of forming hydrogen bonds are more viscous. Larger and heavier atoms and molecules exhibit stronger dispersion forces than smaller and lighter ones. In a larger atom or molecule, the valence electrons are, on average, farther from the nuclei than in a smaller atom or molecule. They are less tightly held and can more easily form temporary dipoles. Note the correlation between the surface tension of a liquid and the strength of the intermolecular forces: the stronger the intermolecular forces, the higher the surface tension. The stronger the intermolecular forces are, the more energy is required, so the higher the melting point is. Many intermolecular forces depend on how strongly atoms in the molecule attract electrons or their electro negativity.As polarity increases, the IMF increase and the mp and bp increase. This is because the stronger the IMF the harder it is to pull these molecules apart so a higher temperature is needed for melting and boiling. Both molecules contain London Dispersion Force and Dipole-Dipole moment but HF has an additional hydrogen bonding which is a strong intermolecular force of attraction. Therefore, we can expect that HF will exhibit a stronger intermolecular force of attraction than HCl. If the kinetic energy is less than the attractive forces, a liquid or solid will form. The average kinetic energy of the particles in a gas is great enough to overcome the forces of attraction between them. The molecules of a gas move apart when they collide. As the motion of particles increases, particles move further apart. The attractive forces between particles get weaker. The spaces between them increase and the particles can slip past one another. As the motion of particles continues to increase, they move even farther apart. A net force acting on an object will change its motion. This means that a net force will change the kinetic energy of an object. The greater the force, the greater the change in motion and the kinetic energy of the object. We know that by F=−dU/dx formula that when force is attractive in nature potential energy increases and when force is repulsive, potential energy decreases. When the temperature increases, the kinetic energy of the molecules increases which is the result of decrease in force of attraction. The molecules overcome the force of attraction (in general intermolecular forces) so that they can slide past one another between different layers.

There is only one force experimentally known to be in action between charged particles at the subatomic level. It is the Coulomb restoring force.

Ref: Article Introduction to Synchronized Kinematic and Electromagnetic Mechanics

The force of attraction that is present between the molecules of a substance that are held together is known as the intermolecular force of attraction. The intermolecular force is the strongest in solids. The intermolecular force of attraction in liquids is not so strong as in solids. If the molecules have similar molar masses and similar types of intermolecular forces, look for the one that is the most polar or that has the most electronegative atoms or the most hydrogen bonding groups. That one will have the strongest IMF's overall. Stronger intermolecular forces → molecules are more attracted to each other → they stick together better → they are harder to separate from each other. Strong IMF's lead to high boiling points, low vapor pressures, and high heats of vaporization. Hydrogen bonds are generally stronger than ordinary dipole-dipole and dispersion forces, but weaker than true covalent and ionic bonds.The strength of attractive forces between two dipoles depends on the electro negativity and the polarity of the molecule. Electro negativity is the likelihood of an electron to hoard electrons and exhibit a negative charge. The higher the electro negativity, the stronger the dipole-dipole interaction. Higher the intermolecular forces, higher will be the viscosity. When there is a strong intermolecular force, the molecules of the liquids are strongly bonded to each other. This induces a resistance to move. The liquids whose molecules are polar or capable of forming hydrogen bonds are more viscous. The overarching principle involved is simple: the stronger the no covalent interactions between molecules, the more energy that is required, in the form of heat, to break them apart. Higher melting and boiling points signify stronger no covalent intermolecular forces. If the kinetic energy is less than the attractive forces, a liquid or solid will form. The average kinetic energy of the particles in a gas is great enough to overcome the forces of attraction between them. The molecules of a gas move apart when they collide. Forces between objects can cause a change in motion. When two objects interact, each exerts a force on the other. These forces can transfer energy between objects which can cause changes in their motion. Moving objects have kinetic energy, which is the energy of motion. We know that by F=−dU/dx formula that when force is attractive in nature potential energy increases and when force is repulsive, potential energy decreases.As stated in the kinetic-molecular theory, the temperature of a substance is related to the average kinetic energy of the particles of that substance. When a substance is heated, some of the absorbed energy is stored within the particles, while some of the energy increases the motion of the particles.

Andre

This is crap because you dont know QM

I recomend the book by Linus Pauling

called QM for applications to chemistry.