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An aqueous solution of 2% non-volatile solute exerts a pressure of 1.004 bar at the normal boiling point of the solvent. What is the molar mass of the solute?

An aqueous solution of 2% non-volatile solute exerts a pressure of 1.004 bar at the normal boiling point of the solvent. What is the molar mass of the solute?

Grade:11

1 Answers

Vikas TU
14149 Points
2 years ago
Concentration is given in percent so that take mass of the solution = 100 g
Mass of non-volatile solute = 2% = 2g mass of the solvent = (100 — 2) = 98 g
Molecular mass of solvent (water) = 18
We have to find molecular mass of solute,
The vapour pressure of pure boiling water = 1atm = 1.013 bar.
Change in vapour pressure  = (1.013 — 1.004)
= 0.009 bar
 ° -  /  ° = w2 × m1 / w1 × m2
0.009 / 1.013 bar = 2g / m2 × 18 g 
m2 = 41.35 g 
Hence,
Molar mass of the solute is 41.35 g 
Let me know if you have doubts especially regarding Physics, Chemistry or Maths.
 

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