Find the pH of each mixture of acids. a. 0.115 M in HBr and 0.125 M in HCHO₂

검증된 단계별 안내

Step 1: Identify the acids involved in the mixture. HBr is a strong acid, and HCHO2 (formic acid) is a weak acid.

Step 2: Calculate the concentration of hydrogen ions [H+] contributed by the strong acid, HBr. Since HBr is a strong acid, it dissociates completely in solution. Therefore, [H+] from HBr is equal to its concentration, 0.115 M.

Step 3: Consider the contribution of hydrogen ions from the weak acid, HCHO2. Since HCHO2 is a weak acid, it does not dissociate completely. However, in the presence of a strong acid, its contribution to [H+] is negligible compared to the strong acid.

Step 4: Determine the total [H+] in the solution. Since the contribution from HCHO2 is negligible, the total [H+] is approximately equal to the [H+] from HBr, which is 0.115 M.

Step 5: Calculate the pH of the solution using the formula pH = -\(\log\)[H+]. Substitute the total [H+] into the formula to find the pH.

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주요 개념

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Strong vs. Weak Acids

Strong acids, like HBr, completely dissociate in solution, releasing all their hydrogen ions (H+). In contrast, weak acids, such as formic acid (HCHO2), only partially dissociate, establishing an equilibrium between the undissociated acid and its ions. Understanding the difference between these types of acids is crucial for calculating the pH of mixtures.

pH Calculation

pH is a measure of the hydrogen ion concentration in a solution, calculated using the formula pH = -log[H+]. For strong acids, the pH can be directly derived from their molarity, while for weak acids, the pH requires the use of the acid dissociation constant (Ka) to determine the concentration of H+ ions at equilibrium.

Acid-Base Mixtures

When mixing strong and weak acids, the strong acid will dominate the pH due to its complete dissociation. However, the presence of the weak acid can affect the overall pH depending on its concentration and dissociation. Analyzing the contributions of both acids is essential for accurately determining the final pH of the mixture.

Find the pH of each mixture of acids. a. 0.115 M in HBr and 0.125 M in HCHO2