Why is the mass determined by measuring a colligative property in case of
some solutes abnormal ? Discuss it with the help of Vant Hoff factor.EXPLAIN IN DETAIL WITH LOGIC.
The molar mass of a substance calculated from the colligative properties is either higher or lower than the expected molar mass. The observed molar mass of a substance is known as abnormal molar mass. The abnormal molar mass is obtained due to dissociation or association of the molecules of the substance,
In such a case, a correction term is introduced to get rid from abnormal masses. This is known as Van't Hoff factor and denoted by i. Van't Hoff factor i, determines the extent of association or dissociation, which can lead to abnormal molar mass of a substance. It can be calculated as:
In such a case, a correction term is introduced to get rid from abnormal masses. This is known as Van't Hoff factor and denoted by i. Van't Hoff factor i, determines the extent of association or dissociation, which can lead to abnormal molar mass of a substance. It can be calculated as:
For example: A solute is undergoing tetramerization after dissolution in solution. Now in case of tertamerisation, 4 molecules of a compound undergo association. Therefore, the number of molecules before association are 4 and after association are 1. Thus the Van't Hoff factor in this case will be 1/4.
Now see how this i is involved in calculation of colligative properties:
