Textbook Question
Pick the stronger base from each pair. a. F– or Cl– b. NO2– or NO3–
Ch.16 - Acids and Bases
Chapter 16, Problem 48
Calculate [H3O+] in each aqueous solution at 25 °C, and classify each solution as acidic or basic. a. [OH-] = 1.1 * 10^-9 M b. [OH-] = 2.9 * 10^-2 M c. [OH-] = 6.9 * 10^-12 M
Verified step by step guidance1
Use the water dissociation constant at 25 °C, which is Kw = 1.0 \times 10^{-14} \text{ M}^2, to find [H_3O^+].
For each solution, apply the formula [H_3O^+] = \frac{Kw}{[OH^-]} to calculate the hydronium ion concentration.
Substitute the given [OH^-] values into the formula: a. [OH^-] = 1.1 \times 10^{-9} \text{ M}, b. [OH^-] = 2.9 \times 10^{-2} \text{ M}, c. [OH^-] = 6.9 \times 10^{-12} \text{ M}.
Determine the nature of each solution: If [H_3O^+] > 1.0 \times 10^{-7} \text{ M}, the solution is acidic; if [H_3O^+] < 1.0 \times 10^{-7} \text{ M}, the solution is basic.
Classify each solution based on the calculated [H_3O^+]: a. Compare [H_3O^+] to 1.0 \times 10^{-7} \text{ M}, b. Compare [H_3O^+] to 1.0 \times 10^{-7} \text{ M}, c. Compare [H_3O^+] to 1.0 \times 10^{-7} \text{ M}.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
pH and pOH Relationship
The pH and pOH of a solution are related through the equation pH + pOH = 14 at 25 °C. This relationship allows us to determine the acidity or basicity of a solution by calculating one from the other. A pH less than 7 indicates an acidic solution, while a pH greater than 7 indicates a basic solution.
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Ion Product of Water
The ion product of water (Kw) is a constant at 25 °C, equal to 1.0 x 10^-14. This means that the product of the concentrations of hydrogen ions [H3O+] and hydroxide ions [OH-] in pure water is always 1.0 x 10^-14. This relationship is crucial for calculating [H3O+] from given [OH-] concentrations.
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Acidic and Basic Solutions
A solution is classified as acidic if [H3O+] > [OH-] and basic if [H3O+] < [OH-]. By calculating [H3O+] from the provided [OH-] values using the ion product of water, we can determine the nature of each solution. This classification is essential for understanding the behavior of different solutions in chemical reactions.
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