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 41

Chapter 10, Problem 41

Complete the following table:

Verified step by step guidance

Step 1: Recall the relationship between pH and the concentration of hydronium ions ([H₃O⁺]). The formula is:

pH = - \log^{(} [H₃O⁺])

. Rearrange this formula to solve for [H₃O⁺]:

[H₃O⁺] = 10^{-} pH

Step 2: Substitute the given pH value (2.50) into the formula to calculate [H₃O⁺]. This will give the concentration of hydronium ions in moles per liter.

Step 3: Use the relationship between [H₃O⁺] and [OH⁻] in water, which is governed by the ion product constant for water:

K w_{=} [H₃O⁺] \times [OH⁻]

. At 25°C,

K w_{=} 10^{- 14}

. Rearrange this formula to solve for [OH⁻]:

[OH⁻] = 10^{- 14} / [H₃O⁺]

Step 4: Determine whether the substance is acidic, neutral, or basic based on the pH value. A pH less than 7 indicates an acidic solution, a pH of 7 indicates a neutral solution, and a pH greater than 7 indicates a basic solution. Since the pH is 2.50, the solution is acidic.

Step 5: Complete the table by filling in the calculated values for [H₃O⁺] and [OH⁻], and indicate that the solution is acidic based on the pH value.

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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 scale is logarithmic, meaning each whole number change represents a tenfold change in acidity or basicity.

Hydronium and Hydroxide Ions

In aqueous solutions, the concentration of hydronium ions (H3O+) and hydroxide ions (OH-) determines the pH. An increase in H3O+ concentration results in a lower pH (more acidic), while an increase in OH- concentration results in a higher pH (more basic). The product of these concentrations is constant at 25°C, known as the ion product of water.

Acidic, Neutral, or Basic Solutions

Solutions can be classified as acidic, neutral, or basic based on their pH values. Acidic solutions have a pH less than 7, neutral solutions have a pH of exactly 7, and basic solutions have a pH greater than 7. The classification helps in understanding the chemical behavior and reactivity of substances in different environments.