Answer:
[tex]T_S=-1.09\°C[/tex]
Explanation:
Hello!
In this case, since the freezing point depression for a solution is computed via:
[tex](T_S-T_W)=-imK_f[/tex]
Whereas TW is the freezing temperature of water, TS that of the solution, i the van't Hoff's factor (3 for K2S as it ionizes properly), m the molality of the solution and Kf the freezing point constant of water. Thus, we plug in to obtain:
[tex](T_S-0\°C)=-3*0.195m*1.86\frac{\°C}{m}\\\\T_S=-1.09\°C[/tex]
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