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Ch.16 - Acids and Bases
Chapter 16, Problem 50b,c

Calculate [H3O+] and [OH] for each solution at 25 °C. b. pH = 11.23 c. pH = 2.87

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Key Concepts

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

pH Scale

The pH scale measures the acidity or basicity of a solution, ranging from 0 to 14. A pH of 7 is considered neutral, while values below 7 indicate acidity and values above 7 indicate basicity. The pH is defined as the negative logarithm of the hydrogen ion concentration, [H+], in a solution, which is crucial for determining the concentration of hydronium ions, [H3O+].
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Ion Product of Water (Kw)

The ion product of water, Kw, is the equilibrium constant for the self-ionization of water, defined as Kw = [H3O+][OH-] = 1.0 x 10^-14 at 25 °C. This relationship allows us to calculate the concentration of hydroxide ions, [OH-], when the concentration of hydronium ions, [H3O+], is known, and vice versa. Understanding Kw is essential for solving problems involving pH and pOH.
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Hydronium and Hydroxide Ion Concentrations

In aqueous solutions, the concentrations of hydronium ions, [H3O+], and hydroxide ions, [OH-], are inversely related due to the ion product of water. For a basic solution, like one with a pH of 11.23, [H3O+] will be lower than 1.0 x 10^-7 M, while [OH-] will be higher than 1.0 x 10^-7 M. Calculating these concentrations is essential for understanding the solution's properties and behavior.
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