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Ch.15 - Chemical Equilibrium
All textbooksMcMurry 8th EditionCh.15 - Chemical EquilibriumProblem 144
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Chapter 15, Problem 144

Vinegar contains acetic acid, a weak acid that is partially dissociated in aqueous solution: CH3CO2H1aq2 ∆ H+ 1aq2 + CH3CO-1aq2 (b) What is the value of Kc if the extent of dissociation in 1.0 M CH3CO2H is 0.42%?

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Weak Acids and Dissociation

Weak acids, like acetic acid, do not completely dissociate in solution. Instead, they establish an equilibrium between the undissociated acid and its ions. The extent of dissociation indicates how much of the acid has converted to ions, which is crucial for calculating equilibrium constants.
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Equilibrium Constant (Kc)

The equilibrium constant, Kc, quantifies the ratio of the concentrations of products to reactants at equilibrium for a given reaction. For the dissociation of acetic acid, Kc can be calculated using the concentrations of H+ and CH3CO- ions relative to the undissociated CH3CO2H, reflecting the extent of the reaction.
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Calculating Concentrations from Extent of Dissociation

To find Kc, one must first determine the concentrations of the species at equilibrium based on the initial concentration and the extent of dissociation. For a 1.0 M solution with 0.42% dissociation, the concentrations of H+ and CH3CO- can be calculated, allowing for the determination of Kc using the equilibrium expression.
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