A 100.0 mL sample of a solution that is 0.100 M in HCl and 0.100 M in HCN is titrated with 0.100 M NaOH. Calculate the pH after the addition of the following volumes of NaOH:
(a) 0.0 mL

검증된 단계별 안내

Step 1: Identify the species present in the solution before the titration begins. In this case, we have HCl, a strong acid, and HCN, a weak acid. The strong acid will completely ionize, while the weak acid will partially ionize.

Step 2: Calculate the initial concentrations of the species. The concentration of HCl is 0.100 M, and it will completely ionize to form H+ and Cl-. The concentration of HCN is also 0.100 M, but it will only partially ionize. Therefore, the initial concentration of H+ ions will be 0.100 M from the HCl, and a small additional amount from the HCN.

Step 3: Since no NaOH has been added yet, we don't need to consider any reactions with NaOH. The pH of the solution will be determined solely by the H+ concentration.

Step 4: Use the formula for pH, which is pH = -log[H+]. In this case, [H+] is the concentration of H+ ions in the solution.

Step 5: Substitute the value of [H+] into the pH formula to calculate the pH of the solution. Remember that the concentration of H+ ions is the sum of the ions from the HCl and the HCN.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Acid-Base Chemistry

Acid-base chemistry involves the study of substances that can donate protons (acids) or accept protons (bases). In this context, HCl is a strong acid that completely dissociates in solution, while HCN is a weak acid that partially dissociates. Understanding the behavior of these acids in solution is crucial for predicting the pH changes during titration.

Titration

Titration is a quantitative analytical method used to determine the concentration of a solute in a solution. In this scenario, NaOH is added to the acid solution to neutralize it. The point at which the amount of titrant (NaOH) added is stoichiometrically equivalent to the amount of acid present is known as the equivalence point, which is essential for calculating pH at various stages of the titration.

pH Calculation

pH is a measure of the acidity or basicity of a solution, calculated as the negative logarithm of the hydrogen ion concentration. At the start of the titration (0.0 mL NaOH added), the pH is determined solely by the concentrations of HCl and HCN. Understanding how to calculate pH from the concentrations of acids and bases is vital for solving the problem presented.

A 100.0 mL sample of a solution that is 0.100 M in HCl and 0.100 M in HCN is titrated with 0.100 M NaOH. Calculate the pH after the addition of the following volumes of NaOH:(a) 0.0 mL