Find the pH of each mixture of acids. a. 0.075 M in HNO₃ and 0.175 M in HC₇H₅O₂ b. 0.020 M in HBr and 0.015 M in HClO₄ c. 0.095 M in HF and 0.225 M in HC₆H₅O d. 0.100 M in formic acid and 0.050 M in hypochlorous acid

Verified step by step guidance

1. Identify the type of acids in each mixture: strong or weak. Strong acids completely dissociate in water, while weak acids do not.
2. For each mixture, calculate the concentration of hydrogen ions [H⁺] contributed by the strong acids, as they dissociate completely. Use the formula [H⁺] = concentration of the strong acid.
3. For weak acids, use the acid dissociation constant (Ka) to find the concentration of hydrogen ions. Set up the equilibrium expression for the weak acid: Ka = [H⁺][A⁻]/[HA], and solve for [H⁺].
4. Add the [H⁺] from the strong acid and the [H⁺] from the weak acid to find the total [H⁺] in the solution.
5. Calculate the pH of the solution using the formula pH = -log[H⁺].

Key Concepts

pH Scale

The pH scale measures the acidity or basicity of a solution, ranging from 0 to 14. A pH less than 7 indicates an acidic solution, while a pH greater than 7 indicates a basic solution. The scale is logarithmic, meaning each whole number change represents a tenfold change in hydrogen ion concentration. Understanding pH is crucial for determining the strength of acids and their effects in mixtures.

Strong vs. Weak Acids

Acids are classified as strong or weak based on their ability to dissociate in water. Strong acids, like HNO3 and HBr, completely ionize in solution, contributing to a higher concentration of hydrogen ions. Weak acids, such as HF and formic acid, only partially dissociate, resulting in a lower concentration of hydrogen ions. This distinction is essential for calculating the pH of mixtures containing different types of acids.

Acid Mixture Calculations

When calculating the pH of mixtures containing multiple acids, it is important to consider the contributions of each acid to the overall hydrogen ion concentration. For strong acids, the total concentration can be directly summed, while for weak acids, the dissociation equilibrium must be considered. This involves using the acid dissociation constant (Ka) for weak acids to determine their effective contribution to the pH of the solution.