Chemistry Equilibrium NUMS 2019
PMDC Verified Question 80 of 102
Precipitation occurs when the product of ionic concentration is?
A
Greater than \( K_{sp} \)
B
Less than \( K_{sp} \)
C
Equal to \( K_{sp} \)
D
Equal to unity
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Greater than \( K_{sp} \)
Concept:

The relationship between the ionic product (\( Q_{sp} \)) and the solubility product (\( K_{sp} \)) determines whether a solution is unsaturated, saturated, or supersaturated.

Formula:

$$ \text{If } Q_{sp} > K_{sp} \implies \text{Precipitation} $$

Solution:

  • \( Q_{sp} \) represents the actual product of ion concentrations in a solution at any given moment.


  • When \( Q_{sp} > K_{sp} \), the solution contains more dissolved ions than it can stably hold at equilibrium (supersaturated).


  • To restore equilibrium, the excess ions precipitate out as a solid until \( Q_{sp} \) drops down to equal \( K_{sp} \).


Why other options are incorrect:

Less than \( K_{sp} \) means the solution is unsaturated (no precipitation). Equal to \( K_{sp} \) means it is perfectly saturated (equilibrium, no net precipitation).

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