Question

The normal boiling point of ethyl
acetate is 77.06°c. A solution of
50g of a non-volatile solution 150g
of Ethyl acetate boiling point at
84.27°c Evaluate the molar mass
of solution if kb for ethyl acetate
is 2.77°C kg/mol​

Answer 1

Answer:

Explanation:

Δ t = 84.27-77.06

= 7.21

Δt= k m

m= 2.77 * 50/7.21*150

= 59.8 g

=

Answer 2

Given :

Boiling point of ethyl acetate ($T_b$°) = 77.06°C

Boiling point of the solution ($T_b$) = 84.27°C

To Find :

Molar mass of the solute

Solution :

We know, elevation of boiling point (Δ$T_b$) is directly proportional to molal concentration of the solution.

            Δ$T_b$    ∝   Molality (m)

∴  Elevation of boiling point (Δ$T_b$) = $K_b$ × Molality (m)

⇒             $T_b$    -     $T_b$°                     =  2.77 × $\frac{Moles Of Solute}{Weight Of Solvent}$

⇒          84.27 -   77.06                  =  2.77 × $\frac{50/ Molar Mass}{150}$×1000

⇒           7.21                                   =  $\frac{923.33}{Molar Mass}$

⇒         Molar Mass                        =  128.06 gm

Therefore, the molar mass of the solute is 128.06 gm.