There are 3 intermolecular forces that are keeping the molecules attracted:
1. London Dispersion Forces
3. Hydrogen Bonding
London Dispersion Forces- the force of attraction between all molecules (any two at one time), created by temporary dipoles, which are caused by the movement of electrons around two atoms.
So, London Dispersion has an effect on all molecules, and these temporary dipoles are the temporary shift in electrons as they change their positions. London Dispersion Forces are very weak, easy to pull nonpolar from nonpolar.
Dipole-Dipole- an electrostatic attraction caused by the positive end of one dipole being attracted to the negative end of another dipole.
Dipole-Dipole is asymmetrical, and applies to hydrogen peroxide because it is a polar molecule. Discussed in the polarity post is the requirements of being a polar molecule. The basic idea that the uneven distribution of electrons proves dipole-dipole to be true in that the positives attract the negatives and vice versa.
Hydrogen Bonding- a special case of dipole-dipole attraction where a temporary covalent bond forms between the hydrogen molecule, and the O,N,F of an adjacent molecule.
Hydrogen Bonding is applicable to hydrogen peroxide through the simplicity of O and H being attracted to each other, forming a bond.