select the correct answer. which of the following aqueous solutions has the lowest freezing point? a. 1.0 m…

Explanation:

Step1: Recall the freezing - point depression formula

The freezing - point depression formula is $\Delta T_f = iK_fm$, where $\Delta T_f$ is the change in freezing point, $i$ is the van't Hoff factor, $K_f$ is the cryoscopic constant (same for all aqueous solutions here), and $m$ is the molality (assume it's the same as molarity for dilute solutions and in this case, all are 1.0 M). The solution with the highest $i$ value will have the greatest $\Delta T_f$ and thus the lowest freezing point.

Step2: Determine the van't Hoff factor for each compound

• For A. $NaCl$, it dissociates into $Na^+$ and $Cl^-$, so $i = 2$.
• For B. $MgBr_2$, it dissociates into $Mg^{2 + }$ and $2Br^-$, so $i=3$.
• For C. $C_{12}H_{22}O_{11}$, it is a non - electrolyte and does not dissociate in water, so $i = 1$.
• For D. $LiF$, it dissociates into $Li^+$ and $F^-$, so $i = 2$.

Answer:

B. 1.0 M ionic $MgBr_2$