Beginning Organic Chemistry (BOC)
7. Physical Properties.
Return to BOC Index.
Solubility depends on the similarity of the intermolecular forces between the two compounds. Similar intermolecular forces lead to mixing of the two compounds as one molecule type will attract the other.
Dissimilar intermolecular forces will lead to one molecular type attracting only its own type, squeezing the other out so that mixing does not occur.
This leads to 'Like dissolves like' as the general rule.
The non-polar alkanes will dissolve other non-polar compounds. Acetone, a fairly polar organic compound, will dissolve many organic compounds. Water, a polar compound, will dissolve only polar organic compounds (with few carbons).
The table below compares the solubility of some alcohols (the -OH makes the alcohol similar to water (H-OH), whereas the carbon chain makes it dissimilar) in the very polar solvent, water.
|Compound||Solubility in Water||Model|
|butan-1-ol||7.4 g per 100 g water|
|pentan-1-ol||2.7 g per 100 g water|
|hexan-1-ol||0.8 g per 100 g water|
|heptan-1-ol||0.1 g per 100 g water|
Date created: 2005 06 11.