Question

Mole fraction of solvent in a
given aqueous
solution is 0.8 Molality of solution is​

Answer 1

Answer:

13.88

Explanation:

The molality (in mol kg⁻¹) of the aqueous solution is (C) 13.88

-Mole fraction of solvent = 0.8

⇒Mole fraction of solute = 1 - mole fraction of solvent

                                        = 1 - 0.8 = 0.2

- Molality = No.of moles of solute / Weight of solvent in kg

          m = No.of moles of solute / (No.of moles of solvent × molar mass of solvent)

{because No of moles of solvent = Weight of solvent / Molar mass of solvent

⇒ Weight of solvent = No.of moles of solvent × molar mass of solvent }

        m = 0.2/(0.8 × 18/1000)  {here solvent is water, so molar mass = 18 gm}

        m = 200/14.4 = 13.88