Ostwald dilution law failed completely when it was applied to:

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DSSSB PGT Chemistry (Female) Official Paper (Held On: 06 Jul, 2018 Shift 1)

Answer 1

CONCEPT:

Ostwald Dilution Law

Ostwald dilution law is applicable to weak electrolytes and relates the dissociation constant of the electrolyte to its degree of dissociation and concentration.
The law states that for a weak electrolyte:
K_a = (α² * C) / (1 - α)
Here, K_a is the dissociation constant, α is the degree of dissociation, and C is the concentration of the electrolyte.
Ostwald dilution law assumes that the electrolyte is weak and does not dissociate completely.

EXPLANATION:

The law fails completely for strong electrolytes like KCl, because strong electrolytes dissociate completely in solution.
For strong electrolytes:
- The degree of dissociation (α) is approximately 1.
- Due to complete dissociation, the assumptions of Ostwald dilution law are invalid, and the law cannot describe their behavior accurately.
In contrast, Ostwald dilution law works well for weak electrolytes like CH₃COOH and H₂CO₃, as their dissociation is partial and can be described using this law.

Therefore, Ostwald dilution law fails completely when applied to strong electrolytes like KCl.