If you want to lower waters freezing point by 23°C by adding $"MgF"_2$ , what must the molality of the solution be?

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Answer 1 · 2018-06-04T23:06:35

$"4.12 molal"$

Change in freezing point is given by

$"ΔT = – iK"_f"m"$

Where

$"m" = "ΔT"/("– iK"_f)$

$color(white)("m") = "– 23°C"/"– 3 × 1.86°C/molal"$

$color(white)("m") = 4.12\ "molal"$

If you want to lower waters freezing point by 23°C by adding "MgF"_2"MgF"_2, what must the molality of the solution be?