Open Question
A 0.25-mol sample of a weak acid with an unknown pKa was combined with 10.0 mL of 3.00 M KOH, and the resulting solution was diluted to 1.500 L. The measured pH of the solution was 3.85. What is the pKa of the weak acid?
Ch.17 - Aqueous Ionic Equilibrium
Chapter 17, Problem 124
Calculate the pH at the beginning of the titration, at the equivalence point, at one-half of the equivalence point, and at 5.0 mL beyond the equivalence point to sketch the titration curve from Problem 123. Then, choose a suitable indicator for this titration from Table 17.1.
Verified step by step guidance1
<insert step 1: Identify the type of titration involved, such as strong acid-strong base, weak acid-strong base, or weak base-strong acid. This will help determine the pH calculations at different points.>
<insert step 2: Calculate the initial pH before any titrant is added. For a weak acid or base, use the initial concentration and the appropriate equilibrium expression to find the pH.>
<insert step 3: Determine the pH at the equivalence point. For a strong acid-strong base titration, the pH will be neutral (pH = 7). For a weak acid-strong base titration, calculate the pH using the conjugate base formed at the equivalence point.>
<insert step 4: Calculate the pH at one-half of the equivalence point. For a weak acid-strong base titration, this is where the pH equals the pKa of the weak acid.>
<insert step 5: Calculate the pH 5.0 mL beyond the equivalence point by determining the concentration of excess titrant and using it to find the pH. Then, choose an indicator whose pH range includes the pH at the equivalence point.>
Related Practice
Textbook Question
A 5.55-g sample of a weak acid with Ka = 1.3⨉10-4 was combined with 5.00 mL of 6.00 M NaOH, and the resulting solution was diluted to 750.0 mL. The measured pH of the solution was 4.25. What is the molar mass of the weak acid?
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Open Question
From the data given—where a 0.552-g sample of ascorbic acid (vitamin C) is dissolved in water to a total volume of 20.0 mL and titrated with 0.1103 M KOH, the equivalence point occurred at 28.42 mL, and the pH of the solution at 10.0 mL of added base was 3.72—determine the molar mass and dissociation constant (Ka) for vitamin C.
Open Question
If a hard water solution is saturated with calcium carbonate, what volume of the solution has to evaporate to deposit 1.00 × 10^2 mg of CaCO3, given that one of the main components of hard water is CaCO3, and when hard water evaporates, some of the CaCO3 is left behind as a white mineral deposit?
Open Question
If the sodium concentration in blood plasma is 0.140 M, and Ksp for sodium urate is 5.76 * 10^-8, what minimum concentration of urate would result in precipitation?
Textbook Question
Pseudogout, a condition with symptoms similar to those of gout (see Problem 126), is caused by the formation of calcium diphosphate (Ca2P2O7) crystals within tendons, cartilage, and ligaments. Calcium diphosphate will precipitate out of blood plasma when diphosphate levels become abnormally high. If the calcium concentration in blood plasma is 9.2 mg/dL, and Ksp for calcium diphosphate is 8.64⨉10-13, what minimum concentration of diphosphate results in precipitation?
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