Which is an advantage of using chemical indicators ?
2 answers:
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Answer: 0.17 m : Highest freezing point
0.20 m : Second lowest freezing point
0.18 m : Third lowest freezing point
0.42 m ethylene glycol: Lowest freezing point
Explanation:
Depression in freezing point is a colligative property which depend upon the amount of the solute.
where,
= change in freezing point
i= vant hoff factor
= freezing point constant
m = molality
a) 0.17 m
For electrolytes undergoing complete dissociation, vant hoff factor is equal to the number of ions it produce. Thus i =2 for , thus total concentration will be 0.34 m
b) 0.18 m
For electrolytes undergoing complete dissociation, vant hoff factor is equal to the number of ions it produce. Thus i = 2 for , thus total concentration will be 0.36 m
c) 0.20 m
For electrolytes undergoing complete dissociation, vant hoff factor is equal to the number of ions it produce. Thus i = 2 for , thus total concentration will be 0.40 m
d) 0.42 m ethylene glycol
For non electrolytes undergoing no dissociation, vant hoff factor is equal to 1 . Thus i = 1 for ethylene glycol, thus concentration will be 0.42 m
The more is the concentration, the highest will be depression in freezing point and thus lowest will be freezing point.
Well, first we must remember that
This is because
So then