Question

Based from following solutions, which will have the lowest freezing point?. . 1 M CaCl2. 1 M MgSo4. 1 M NaCl. 1 M sugar

Answer 1

The 1 M CaCl2 solution will have the lowest freezing point as it dissociates into three ions, offering a higher concentration of dissolved particles compared to the other listed solutions, hence affecting the freezing point more significantly.

Step-by-step explanation:

The question is about identifying which solution has the lowest freezing point among the given options: 1 M CaCl2, 1 M MgSO4, 1 M NaCl, and 1 M sugar. The freezing point depression is a colligative property that depends on the number of particles the solute breaks down into when dissolved. Since CaCl2 and MgSO4 are ionic compounds, they will break down into more ions than NaCl (which breaks into two ions) or sugar (which does not break at all in solution).

The freezing point depression is more significant in solutions where the solute dissociates into more particles. CaCl2 dissociates into three ions (${Ca^{2+}} + 2{Cl^-}$), MgSO4 dissociates into two ions (${Mg^{2+}} + {SO4^{2-}}$), NaCl dissociates into two ions (${Na^+} + {Cl^-}$), and sugar does not dissociate. Therefore, 1 M CaCl2 will have the lowest freezing point as it provides the highest concentration of dissolved particles after dissociation.

Answer 2

The freezing point of a salt solution can be determined by knowing the molality of the solution and the Kf of the solvent. It is also important to know the van't Hoff factor which relates to the number of ions dissociated. In this case, since the concentration and the solvent is constant, the greatest number of ions has the lowest freezing point. The answer is A. 1 M CaCl2.