Estimate the boiling point of a solution of 25.0g of urea `"NH"_(2)"CONH"_(2)` plus 25.0g of thiourea `"NH"_(2)"CSNH"_(2)` in 500g of choloform, `"CHCl"_(3).` The boiling point of pure choloform is `61.2^(@)"C","K"_("b")` of choloform=3.63 `"Km"^("-1")`

Explanation

25 g urea `=(25)/(60)` mole = 0.417 mole, 25 g thiourea `= (25)/(76)` mole = 0.329 mole
Total moles `= 0.417+0.329=0.746`
Mass of solvent `= 500 g = 0.500 kg therefore " Molality"=(0.746 mol)/(0.500 kg)=1.492 m`,
`Delta T_(b)=K_(b)xx m=3.63xx1.492 = 5.416^(@)`
Boiling point of solution `= 61.2+5.416^(@)C=66.616^(@)C`.