Which of the following aqueous solutions has the lowest freezing point?

12. Which of the following aqueous solutions would be expected
to have the lowest freezing point? A) 0.400 m K2SO4 B) 0.400 m NaCl
C) 0.400 m C6H12O6 (glucose) D) 0.040 m K2SO4 E) 0.040 m NaCl

Freezing point of water is depressed (lowered) by the addition
of a solute. The amount of depression in freezing point depends on
the molality of solute particles in that solution. Higher the
molality, lowest the freezing point.
A. 0.4 m K2SO4 has (0.4*2) = 0.8 m
K+ ions and 0.4 m SO4- ions. Total
particles = 0.8+0.4 = 1.2 m
B. 0.4 m NaCl has 0.4 m Na+ ions and 0.4 m
Cl- ions. Total particles = 0.4 +0.4 = 0.8m
C. 0.4 m C6H12O6 has 0.4 m
C6H12O6 ions. Total particles =
0.4 m
D. 0.04 m K2SO4 has (0.04*2) = 0.08 m
K+ ions and 0.04 m SO4- ions.
Total particles = 0.08+0.04 = 0.12 m
E. 0.04 m NaCl has 0.04 m Na+ ions and 0.04 m
Cl- ions. Total particles = 0.04 +0.04 = 0.08m
Therefore A. 0.4
m K2SO4 has highest molality and lowest
freezing poing point.

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