Question

Can you detect any trends in formula, mass and boiling point bp in going down this series of molecules? What would you predict as a rule for determining bp? Can you support your hypothesis?

Answer 1

NOTE ; Since the series of molecules spoken about in the question is not provided, I would present a generalised answer.

let us assume your molecules are organic molecules belonging to a homologues series. Homologues series is a series of organic molecules with same functional groups that differ only in the number of carbon atoms in the carbon chain.

1. From the molecular formula, greater the number of carbon atoms , greater is the length of carbon chain [if not highly branched], thus higher the bp.
2. higher the mass ,higher is the bp as heavy molecules require more energy to break the attractions in liquid state to change into gaseous state.

As a rule, we can state that the bp of molecule depends on the bulkiness of the molecule . Greater the bulkiness and size, greater will be the bp of the molecule.

Yes, our hypothesis can be supported by comparing the bp of molecules of same homologues series.