This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
ScanSolve AI Answer
Temi, let's knock this out. 1. Calculate the pK_a of lactic acid, given that when the concentration of lactic acid is 0.010 M and the concentration of lactate is 0.087 M, the pH is 4.80. Step 1: Use the Henderson-Hasselbalch equation. pH = pK_a + ([conjugate base][weak acid]) Here, lactic acid is the weak acid and lactate is its conjugate base. Step 2: Substitute the given values into the equation. 4.80 = pK_a + (0.087 M0.010 M) Step 3: Calculate the logarithm term. 4.80 = pK_a + (8.7) 4.80 = pK_a + 0.9395 Step 4: Solve for pK_a. pK_a = 4.80 - 0.9395 pK_a = 3.8605 The pK_a of lactic acid is 3.86. 2. Calculate the pH of a mixture of 0.10 M acetic acid and 0.20 M sodium acetate. The pK_a of acetic acid is 4.76. Step 1: Identify the weak acid and its conjugate base. Acetic acid is the weak acid, and sodium acetate provides the acetate ion, which is the conjugate base. [weak acid] = [acetic acid] = 0.10 M [conjugate base] = [acetate] = 0.20 M pK_a = 4.76 Step 2: Use the Henderson-Hasselbalch equation. pH = pK_a + ([conjugate base][weak acid]) Step 3: Substitute the values into the equation. pH = 4.76 + (0.20 M0.10 M) Step 4: Calculate the logarithm term and solve for pH. pH = 4.76 + (2.0) pH = 4.76 + 0.3010 pH = 5.0610 The pH of the mixture is 5.06. 3. Calculate the ratio of the concentrations of acetate and acetic acid required in a buffer system of pH 5.30. The pK_a of acetic acid is 4.76. Step 1: Use the Henderson-Hasselbalch equation. pH = pK_a + ([acetate][acetic acid]) Given pH = 5.30 and pK_a = 4.76. Step 2: Substitute the given values into the equation. 5.30 = 4.76 + ([acetate][acetic acid]) Step 3: Isolate the logarithm term. ([acetate][acetic acid]) = 5.30 - 4.76 ([acetate][acetic acid]) = 0.54 Step 4: Solve for the ratio by taking the antilog (10 to the power of) of both sides. [acetate][acetic acid] = 10^0.54 [acetate][acetic acid] = 3.467 The ratio of the concentrations of acetate to acetic acid is 3.47. 4. The pK of acetic acid is 4.8. What is the approximate pH of an acetate solution containing 0.2 M acetic acid and 2 M acetate ion? Step 1: Identify the weak acid and its conjugate base concentrations, and the pK_a. [weak acid] = [acetic acid] = 0.2 M [conjugate base] = [acetate ion] = 2 M pK_a = 4.8 Step 2: Use the Henderson-Hasselbalch equation. pH = pK_a + ([conjugate base][weak acid]) Step 3: Substitute the values into the equation. pH = 4.8 + (2 M0.2 M) Step 4: Calculate the logarithm term and solve for pH. pH = 4.8 + (10) pH = 4.8 + 1 pH = 5.8 The approximate pH of the solution is 5.8. What's next?