A 0.185 M solution of a weak acid (HA) has a pH of 2.95. Calculate the acid ionization constant

step 1 In this question, 0 .185 molar weak acid is given which has a pH of 2 .95. We have to calculate

A 0.185 M solution of a weak acid (HA) has a pH of 2.95....

Key Concepts

Equilibrium Calculations in Weak Acid Systems

Calculating the equilibrium concentrations in weak acid systems involves setting up the equilibrium expression based on the dissociation of the acid and applying the known initial concentration and measured pH. Approximations often simplify calculations when the degree of dissociation is small, allowing for a more straightforward determination of the acid ionization constant (Ka).

pH and Hydrogen Ion Concentration

pH is a measure of the hydrogen ion concentration in a solution and is defined as the negative logarithm of the hydrogen ion concentration (pH = -log[H+]). It is a critical parameter in acid-base chemistry, as it provides insight into the acidity or basicity of a solution, and is used to relate directly to the degree of dissociation of acids in equilibrium.

Weak Acids

A weak acid is one that does not completely dissociate in aqueous solution. Instead, it establishes an equilibrium between its undissociated form and its ionized form (H+ and A–). This property is central to understanding how weak acids behave in solution and affects calculations related to their ionization and concentration in equilibrium conditions.

Acid Ionization Constant (Ka)

The acid ionization constant, Ka, quantifies the strength of an acid in solution by measuring the extent of its dissociation into hydrogen ions and its conjugate base. It is defined by the equilibrium expression Ka = ([H+][A–])/[HA], where larger values indicate stronger acids that dissociate more completely. This constant is fundamental in acid-base chemistry for comparing the relative strengths of acids.

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