Calcule el porcentaje de disociación del ácido hidrazoico (HN3) en disoluciones de las concentra

step 1 Problem 63, Part A. In given question, given question, okay, hydrozoic acid is dissociated into

Calcule el porcentaje de disociación del ácido hidrazoico...

Calcule el porcentaje de disociación del ácido hidrazoico $\left(\mathrm{HN}_3\right)$ en disoluciones de las concentraciones siguientes (véase la $K_a$ en el Apéndice D): (a) $0.400 \mathrm{M}$; (b) $0.100 \mathrm{M}$; (c) $0.0400 \mathrm{M}$.

Key Concepts

Influence of Concentration on Equilibrium

The initial concentration of the acid affects the percent dissociation; as the concentration decreases, the percentage of acid that dissociates generally increases. This counterintuitive effect arises because a lower concentration shifts the equilibrium position, highlighting the interplay between concentration and equilibrium in weak acid systems.

Percent Dissociation

Percent dissociation is calculated as the fraction of the initial acid molecules that dissociate into ions, typically expressed as a percentage. It is determined by comparing the concentration of dissociated acid (or the produced H+ ions) at equilibrium to the initial concentration of the acid, providing insight into the acid’s effectiveness in donating protons.

Weak Acid Behavior

Weak acids, such as hydrazoic acid in this example, do not completely dissociate in aqueous solution. Instead, they establish an equilibrium between the undissociated acid and the ions produced. Understanding this behavior is key in calculating the degree to which these acids ionize.

Acid Ionization Constant (Ka)

The acid ionization constant, Ka, quantifies the strength of a weak acid by expressing the equilibrium concentration ratio of the products (H+ and the conjugate base) to the undissociated acid. It is essential for determining the extent of dissociation and comparing the acid strengths of various compounds.

Equilibrium Calculations

Equilibrium calculations involve setting up the dissociation reaction and using an ICE (Initial, Change, Equilibrium) table to represent the initial concentrations, the changes during dissociation, and the equilibrium concentrations. This method is fundamental in solving for the equilibrium concentrations of species in a chemical reaction.

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