Question

1a.) Consider the following substance: C25H52. Which intermolecular forces are present?

1b.)What type of question is this?

1c.) How do I know that it is this type of question?

1d.) What information are you looking for?

1e.) What information is given?

Answer 1

Let us answer your question starting from the last one; i.e., 1e.

The information given is the molecular formula of the compound! C₂₅H₅₂.It can be put under a general formula of C_nH_n+2 which is a simple alkane. Alkanes contain C-C single bonds and C-H single bonds and no unsaturation or any other functional groups;

We are looking for the nature of intermolecular forces present in the molecule. In general, intermolecular forces can be divided into several categories: Strong ionic attraction, Intermediate dipole-dipole forces, Weak London dispersion forces or van der Waal's force, Hydrogen bond, Covalent bonding and Metallic bonding. Metallic bonding is a characteristic property of metals.Hydrogen bond is formed between a Hydrogen atom bonded to an electronegative atom such as N,O,F etc. and a second electronegative atom. Two of the remaining, ionic attraction and dipole dipole interactions are present in ionic or weakly ionic molecules. Hence, none of these forces would be present in the given molecule.
Hence, the only intermolecular forces present in the given alkane are weak london dispersion forces or Van der waal's interaction forces. These two forces, infact, operate in any given substance. These are short distance effects and Van der Waals forces include attraction and repulsions between atoms, molecules, and surfaces, as well as other intermolecular forces. They differ from covalent and ionic bonding in that they are caused by correlations in the fluctuating polarizations of nearby particles. Very weak (negligible) induced dipole-induced dipole interaction may also be present.