Which of the following graphs best depicts the relationship between the concentration of a strong electrolyte and the extent of its dissociation in water?

• A. A downward-sloping line showing that dissociation decreases as concentration increases.
• B. A curve that rises steeply at low concentrations and levels off at high concentrations.
• C. A horizontal line indicating that dissociation remains constant regardless of concentration.
• D. A straight line showing that dissociation increases proportionally with concentration.

Answer: (C)

Verified step by step guidance

1. Recall that a strong electrolyte completely dissociates into its ions in aqueous solution, meaning its dissociation extent is essentially 100% regardless of concentration.
2. Understand that the degree of dissociation (α) for a strong electrolyte is nearly constant and does not depend on concentration, unlike weak electrolytes where dissociation varies with concentration.
3. Analyze the given graph options: a downward-sloping line would imply dissociation decreases with concentration, which is not true for strong electrolytes; a curve that rises and levels off suggests partial dissociation increasing with concentration, typical of weak electrolytes; a line increasing proportionally with concentration implies dissociation depends on concentration, which is incorrect for strong electrolytes.
4. Recognize that the correct graph for a strong electrolyte is a horizontal line, indicating that the extent of dissociation remains constant (close to 100%) regardless of changes in concentration.
5. Summarize that since strong electrolytes fully dissociate at all concentrations, their dissociation extent is independent of concentration, which is why the horizontal line best represents this relationship.