Calculate the mass (g) of NaCI that has to be dissolved to reduce the vapour pressure of 100 g of water by 10 % (Molar mass NaCl=58.5gmol- 1 ).(Round off your answer to the nearest integer.)

Question

Calculate the mass (g) of NaCI that has to be dissolved to reduce the vapour pressure of 100 g of water by 10 % (Molar mass NaCl=58.5gmol- 1 ).(Round off your answer to the nearest integer.) (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

The mass (g) of NaCI can be calculated from Raoult's law

P_{s} = P^{0} \times

mole fraction of solvent

90 = 100 \times (\frac{100/18}{\frac{100}{18} + \frac{w \times 2}{58.5}})

0.9 (\frac{100}{18} + \frac{w \times 2}{58.5}) = \frac{100}{18}

\Rightarrow w = 18.11 \sim e q 18 g m

Q. Calculate the mass (g) of NaCI that has to be dissolved to reduce the vapour pressure of 100 g of water by 10% (Molar mass NaCl=58.5gmol−1 ).(Round off your answer to the nearest integer.)

The mass (g) of NaCI can be calculated from Raoult's law Ps​=P0× mole fraction of solvent 90=100×(18100​+58.5w×2​100/18​) 0.9(18100​+58.5w×2​)=18100​ ⇒w=18.11∼eq18gm

Q. Calculate the mass (g) of NaCI that has to be dissolved to reduce the vapour pressure of 100 g of water by $10%$ (Molar mass $N a Cl = 58.5 g m o l^{- 1}$ ).(Round off your answer to the nearest integer.)

The mass (g) of NaCI can be calculated from Raoult's law
$P_{s} = P^{0} \times$ mole fraction of solvent
$90 = 100 \times (\frac{100/18}{\frac{100}{18} + \frac{w \times 2}{58.5}})$
$0.9 (\frac{100}{18} + \frac{w \times 2}{58.5}) = \frac{100}{18}$
$\Rightarrow w = 18.11 \sim e q 18 g m$