Concept explainers
(a)
Interpretation: The molality, calculated freezing points and van’t Hoff factor (i) for the acids in the given table has to be determined
Concept introduction:
Freezing point depression: The freezing point of the solution varies with the solute concentration.
where,
van’t Hoff factor, i: it is the ration between change in in freezing point measured and change in in freezing point calculated. It indicates the total number of ions that are produced.
Molality (m): Molality is the number of moles of solute present in one kilogram of solvent.
The number of moles of any substance can be determined using the equation
(a)
Answer to Problem 106SCQ
Acid (1 mass %) | Molality (mol/kg | i | ||
-0.56 | ||||
-0.32 | ||||
-0.42 | ||||
-0.30 | ||||
-0.42 | ||||
-0.21 |
Explanation of Solution
The number of moles of any substance can be determined using the equation
Molarity of any substance can be determined using the equation
,
Therefore,
For
In
Depression in freezing point is calculated by using the equation
Therefore,
For
For
In
Depression in freezing point is calculated by using the equation
For
For
In
Depression in freezing point is calculated by using the equation
For
For
In
Depression in freezing point is calculated by using the equation
For
For
In
Depression in freezing point is calculated by using the equation
For
For
In
Depression in freezing point is calculated by using the equation
For
Van’t Hoff factor can be find out using the equation,
For
For
For
For
For
For
(b)
Interpretation: The relation of acidic strength with the i value has to be given.
Concept introduction:
van’t Hoff factor, i: it is the ration between change in in freezing point measured and change in in freezing point calculated. It indicates the total number of ions that are produced.
(b)
Answer to Problem 106SCQ
The values of ‘i’ increases in the increasing order of strength of acids.
Explanation of Solution
The increasing order of acidic strength for the given acids is,
The increasing order of ‘i’ value for the given acids is,
Hence,
The values of ‘i’ increases in the increasing order of strength of acids.
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Chapter 13 Solutions
CHEMISTY+CHEMICAL REACTIVITY
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