Respuesta :
Answer: [tex]1.0\times 10^2g[/tex]
Explanation:
Depression in freezing point is given by:
[tex]\Delta T_f=i\times K_f\times m[/tex]
[tex]\Delta T_f=T_f^0-T_f=(-6.4-(13.6))^0C=7.2^0C[/tex] = Depression in freezing point
i= vant hoff factor = 1 (for non electrolyte like urea)
[tex]K_f[/tex] = freezing point constant = [tex]3.96^0C/m[/tex]
m= molality
[tex]\Delta T_f=i\times K_f\times \frac{\text{mass of solute}}{\text{molar mass of solute}}\times \text{weight of solvent in kg}}[/tex]
Weight of solvent (X)= 950 g = 0.95 kg
Molar mass of non electrolyte (urea) = 60.06 g/mol
Mass of non electrolyte (urea) added = ?
[tex]7.2=1\times 3.96\times \frac{xg}{60.06 g/mol\times 0.95kg}[/tex]
[tex]x=1.0\times 10^2g[/tex]
Thus [tex]1.0\times 10^2g[/tex] urea was dissolved.
