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Short Note

**Answer the following in one or two sentences.**

Which of the following solution will have higher freezing point depression and why?

i. 0.1 m NaCl

ii. 0.05 m Al_{2}(SO_{4})_{3}

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#### Solution

For 0.1 m NaCl:

NaCl → Na^{+} + Cl^{-}

0.1 m 0.1 m 0.1 m

Total particles in solution = 0.2 mol

For 0.05 m Al_{2}(SO_{4})_{3}:

Al_{2}(SO_{4})_{3} → 2Al^{3+} + 3`"SO"_4^(2-)`

0.05 m 0.1 m 0.15 m

Total particles in solution = 0.25 mol

Al_{2}(SO_{4})_{3} solution contains more number of particles than NaCl solution. Hence, Al_{2}(SO_{4})_{3} solution has maximum ΔT_{f}.

Therefore, the freezing point depression of 0.05 m Al_{2}(SO_{4})_{3} solution will be higher than 0.1 m NaCl solution.

Concept: Colligative Properties of Electrolytes

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