Question

Mass of non-volatile solute (X) which should be, dissolved in 58 g of acetone to reduce its vapour pressure to 90% will be (Atomic mass of X = 4) ​

Answer 1

Answer:

8gm

Explanation:

answer is 8gm. Here, X= 8gm

Answer 2

Mass of non-volatile solute (X) which should be, dissolved in 58 g of acetone to reduce its vapour pressure to 90% will be 0.4 g.

Calculations:

  Given-

• m(solute) = 4 g/mol
• w(solute) = ?
• M (solvent) = 58 g , Molecular mass of acetone
• W (solvent) = 58 g

Let p° be the pressure of the pure solvent,

p (solution) = 90/100 x p°

                   =  0.9 p°

According to Rauolt's Law

   (p°- p) / p° = n(solute)/ n(solvent)

   0.1p°/p°    = (w/m) / (W/M)

      0.1    =  w/4  x  58/58

       w = 0.4

Mass of non-volatile solute = 0.4g should be, dissolved in 58 g of acetone to reduce its vapour pressure to 90%.