1.

Calculate the boiling point of a solution containing 25 g urea (NH_(2)CONH_(2)) and 25 g thiourea (NH_(2)CSNH_(2)) in 500 g chloroform, CHCl_(3). The boiling point of pure chloroform is 61.2^(@)C and K_(b)=3.63 K m^(-1).

Answer»

SOLUTION :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 kgtherefore "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`.


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