Respuesta :
Answer: [tex]2.49^0C[/tex]
Explanation:
Depression in freezing point is:
[tex]T_f^0-T_f=i\times k_f\times \frac{w_2\times 1000}{M_2\times w_1}[/tex]
where,
[tex]T_f[/tex] = freezing point of solution = ?
[tex]T^o_f[/tex] = freezing point of solvent (cyclohexane) = [tex]6.50^oC[/tex]
[tex]k_f[/tex] = freezing point constant of solvent (cyclohexane) = [tex]20.0^oC/m[/tex]
m = molality
i = Van't Hoff factor = 1 (for non-electrolyte)
[tex]w_2[/tex] = mass of solute (biphenyl) = 0.771 g
[tex]w_1[/tex] = mass of solvent (cyclohexane) = 25.0 g
[tex]M_2[/tex] = molar mass of solute (biphenyl) =
Now put all the given values in the above formula, we get:
[tex](6.50-T_f)^oC=1\times (20.0^oC/m)\times \frac{(0.771g)\times 1000}{154\times (25.0g)}[/tex]
[tex](6.50-T_f)^oC=4.01[/tex]
[tex]T_f=2.49^0C[/tex]
Therefore, the freezing point of a solution made by dissolving 0.771 g of biphenyl in 25.0 g of cyclohexane is [tex]2.49^0C[/tex]
