A solution of urea (mol. mass 56 ~g ~mol ⁻¹ ) boils at 100.18^ C at the atmospheric pressure. If k_f and k_b for water are 1.86 and 0.512 ~K ~kg ~mol ⁻¹ respectively, the above solution will freeze at

Step-by-step solution

aligned T_f & =k_f Molality of solution T_b & =k_b Molality of solution aligned or T_f T_b = k_f k_b Given that T_b=T₂-T₁=100.18-100=0.18 aligned & k_f for water =1.86 ~K ~kg ~mol ⁻¹ & k_b for water =0.512 ~K ~kg ~mol ⁻¹ aligned T_f 0.18 = 1.86 0.512 aligned T_f & = 1.86 0.18 0.512 & =0.6539 0.654 T_f & =T₁-T₂ 0.654 & =0^ C -T₂ aligned T₂=-0.654^ C ( T₂ Freezing point of aqueous urea solution)