Abstract:
The partial molar volumes of a number of ethers, ketones, esters and alcohols in water at 25.0°C have been determined and related to their van der Waals volumes by one of two equations, depending on whether the molecules are spherical or cylindrical in shape. Allowance has been made for the void volume associated with each molecule and the results imply that calculated volumes must be reduced by a constant amount for each carbonyl or hydroxyl group present, owing to hydrogen bonding to water. No such reduction in the calculated volume is required for the oxygen atom of an ether. It is shown for diols that the amount of void volume per additional —CH2— group remains constant for straight-chain compounds (i.e., cylinders), whereas for spherical molecules the amount of void volume decreases with increase in the number of carbon atoms, as predicted.
