Ch.10 Acids and Bases and Equilibrium

Timberlake - Chemistry: An Introduction to General, Organic, and Biological Chemistry 13th Edition

Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook

Timberlake 13th Edition

Ch.10 Acids and Bases and Equilibrium

Problem 39f

Chapter 10, Problem 39f

Calculate the pH of each solution given the following:
f. [OH^-] = 8.2 × 10^-4 M

Verified step by step guidance

Step 1: Recall the relationship between pH, pOH, and the concentration of hydroxide ions ([OH⁻]). The formula to calculate pOH is:

pOH = - \log ({[OH]}_{-})

Step 2: Substitute the given [OH⁻] value (8.2 × 10⁻⁴ M) into the formula for pOH. This will give you the pOH of the solution.

Step 3: Use the relationship between pH and pOH, which is:

pH = 14 - pOH

. Subtract the calculated pOH from 14 to find the pH.

Step 4: Ensure that your final pH value is reasonable. For a solution with a relatively high [OH⁻], the pH should be greater than 7, indicating a basic solution.

Step 5: Double-check your calculations for accuracy, especially when using logarithms and subtraction, to ensure the correct pH value is obtained.

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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 alkalinity. The scale is logarithmic, meaning each whole number change represents a tenfold change in hydrogen ion concentration.

Hydroxide Ion Concentration

Hydroxide ions (OH⁻) are negatively charged ions that play a crucial role in determining the basicity of a solution. The concentration of hydroxide ions can be used to calculate the pOH of a solution, which is related to pH through the equation pH + pOH = 14. Understanding the concentration of OH⁻ is essential for calculating the corresponding pH.

Relationship Between pH and pOH

The relationship between pH and pOH is defined by the equation pH + pOH = 14 at 25°C. This means that if you know the pOH of a solution, you can easily find its pH by subtracting the pOH from 14. This relationship is fundamental in acid-base chemistry and is crucial for solving problems involving pH calculations.

Calculate the pH of each solution given the following:f. [OH-] = 8.2 × 10-4 M