Question

Describe the main forces that occur between molecules of butane and explain how they arrive?

Answer 1

The main intermolecular forces between molecules of butane are London dispersion forces (Van der Waals forces). Although butane is nonpolar, the movement of electrons in their orbitals means that extremely brief, weak dipoles form (i.e. at any given time, the part of the orbital with the electron is "more negative" and the part of the orbital without the electron is "more positive").

These temporary dipoles allow different molecules of butane to interact with one another. Although they are very weak and short-lived, when you consider all the temporary dipoles that are constantly forming and disappearing along the entire butane molecule, you can see it becomes a significant force.

Answer 2

H3C-CH2-CH2-CH3
ion-ion bonds: not an ion
ion-dipole bonds: not an ion and no dipole
dipole-dipole bonds: butane is nonpolar, so no dipole
Hydrogen bonds: does not contain H bonded to F,O, or N

therefore the only intramolecular bonds remaining are the weakest of the weak - london dispersion forces (aka Van Der Waals). These are randomly induced dipole attractions that happen when the electrons that move around randomly just happen to have a higher concentration at one end of the molecule. This causes dipoles to form in adjacent molecules, which induce dipoles in molecules next to them. these forces are very weak, but still play a part in raising the boiling point of butane.

Answer 3

Ok thanks..! The same question regarding butane which i don't understand is:
Ques: A canister of gas, as used in camping stoves, contains mainly butane under sufficient pressure to cause it to liquify partially, would you expect the gas in the canister to behave as an ideal gas? Explain