Jenkin writes: When we say higher than expected, in this context it means higher than if the mixture showed ideal behaviour. If it behaved ideally, the intermolecular forces between propanone and trichloromethane would be similar to those between molecules of the pure, separate liquids. But here there are hydrogen bonds between the hydrogen atom of trichloromethane and the oxygen atom of propanone. These higher than expected intermolecular forces mean that the mixture will have a higher than expected boiling point. Notre that hydrogen bonding involving C-H bonds is very, very unusual. However in trichloromethane, the three electronegative chlorine atoms attached to the carbon atom have the effect of polarising the C-H bond sufficiently to allow a degree of hydrogen bonding with teh oxygen atom in propanone. Risk assessment Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from thes