I have a doubt in elevation of boiling point and depression of freeing point.
Suppose you have three compounds K2SO4(potassium sulphate) , NaCl (sodium chloride) and
C6H12O6 (glucose). Then on what basis can you tell which will have more elevation in boiling point and more depression in freezing point when dissolved in water?
1
Expert's answer
2012-10-25T10:35:53-0400
The van 't Hoff factor (і) is a measure of the effect of a solute upon colligative properties such as osmotic pressure, relative lowering in vapor pressure , elevation of boiling point and freezing point depression. If the solute substance dissociates into n ions, then:
і = 1 + α(n - 1) ∆Tb = і Kb · m ∆Tf = і Kf · m
When solute particles dissociate in solution, і is greater than 1. (eg sodium chloride in water,potassium sulphate in water, magnesium chloride in water). When solute particles neither dissociate nor associate in solution, і equals 1. ( eg Glucose in water). So K2SO4 (potassium sulphate), NaCl (sodium chloride) will have more elevation in boiling point and more depression in freezing point when dissolved in water , because its have і >1. And C6H12O6 (glucose) will have less elevation in boiling point and more depression in freezing point when dissolved in water, because it has і = 1.
Comments
Leave a comment