Question

Calculate the solubility of p-dibromobenzene in benzene at 20°C and 40°C assuming ideal solutions are formed. The enthalpy of fusion of p-dibromobenzene is 13.22 kJ/mol and its melting point is 86.9 °C. Ideal sulubility

Answer 1

Sol. In case of ideal solution the heat of solution is equal to the heat of the fusion solid component and activity of the solution becomes equal the mole fraction .

So the formula will be modified to:

$log x _{2}= \frac{-\Delta H_{fusion}}{2.303 R}(\frac{1}{t}-\frac{1}{T_{0}})$ ; where $x _{2}$ = mole fraction

t = Temperature of the solution

$T_0$= melting point of the solute

  $\Delta H_{fusion}$ = enthalpy of fusion

R = Universal constant

Since the ideal solution, so the mole fraction is equal to the solubility of the solute in the solution since in case of ideal solution we assume dilute solutions to be there.

2.303 R M, -0.4 374 Bol In case of ideal solution the heat of solution is quel to the heat of fusion of sold component and activity of the constituents is equal to the mole fraction iso 2= m de fraction log as = -Amfumom. [t to] to tomp of som -1 To log me = - 13-22x10° 1 mp. of solur 2.303x 8-314 L293:2 360-8 T: 20Ć = zette 293* To=86.9°C 350.9k 22*0.365 here we will be equivaleur to solubility in cese ided solution $: 03651 now for T: 40°C = 2 313.2k logne = nguperior [+ to] log?,= -13.22X103 Lə13.2 360.0 logmei - 0.2871 4,-0.5163 leur mole fraction will coveespond to solubility an cep is: 0-5163 2.303 R .303 X 8.314 313.2 3