A solution containing 10 g per dm3 of urea is isotonic with a 5% solution of non volatile solute. Calculate the molecular mass of this non-volatile solute.
Step 1: Calculating the concentration of urea
The molar mass of urea is
The concentration of urea is:
Step 2: Calculating the molecular mass
Let the molar mass of the non-volatile solute be M
The concentration of 5% non-volatile solute is:
Now for isotonic at the same temperature, we know that the concentration is equal
Therefore, the molecular mass of this non-volatile solute is .