Question
A 4% solution of sucrose is isotonic with 3% solution of an unknown organic substance. Calculate the molecular mass of unknown resistance.
Solution
Answer:
AS both the solution are isotonic they should have same concentrationin mole/litre
for sucrose solution concentration =4g/100cm3
= 40g/Litre
molar mass of sucrose C 12H22O11 = 342
therefore we get =40/342 moles/litre
For unknown substance Let N be the molecular mass then concentration = 3g/100cm3
= 30g/Litre
= 30/N moles/Litre
comparing the both equation
30/N = 40/342
N=(30 x 342)/40
N= 256.5
Molecular mass of oragnic compound
