I Review | Constants | Periodic Table Part A As a technician in a large pharmaceutical research firm, you need to produce 150. mL of a potassium dihydrogen phosphate buffer solution of pH = 6.98. The pKa of H2PO4 is 7.21. You have the following supplies: 2.00 L of 1.00 M KH2PO4 stock solution, 1.50 L of 1.00 M K2HPO4 stock solution, and a carboy of pure distilled H2O. How much 1.00 M KH2PO4 will you need to make this solution? (Assume additive volumes.) Express your answer to three significant digits with the appropriate units. • View Available Hint(s) ? Volume of KH2PO4 needed = Value Units

I Review | Constants | Periodic Table Part A As a technician in a large pharmaceutical research firm, you need to produce 150. mL of a potassium dihydrogen phosphate buffer solution of pH = 6.98. The pKa of H2PO4 is 7.21. You have the following supplies: 2.00 L of 1.00 M KH2PO4 stock solution, 1.50 L of 1.00 M K2HPO4 stock solution, and a carboy of pure distilled H2O. How much 1.00 M KH2PO4 will you need to make this solution? (Assume additive volumes.) Express your answer to three significant digits with the appropriate units. • View Available Hint(s) ? Volume of KH2PO4 needed = Value Units

Chemistry: Principles and Reactions

8th Edition

ISBN:9781305079373

Author:William L. Masterton, Cecile N. Hurley

Publisher:William L. Masterton, Cecile N. Hurley

Chapter14: Equilibria In Acid-base Solutions

Section: Chapter Questions

Problem 51QAP: Consider a 10.0% (by mass) solution of hypochlorous acid. Assume the density of the solution to be...

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Malonic acid (HO2CCH2CO2H) is a diprotic acid. In the titration of malonic acid w ith NaOH, stoichiometric points occur at pH = 3.9 and 8.8. A 25.00-mL sample of malonic acid of unknown concentration is titrated with 0.0984 M NaOH, requiring 31.50 mL of the NaOH solution to reach the phenolphthalein end point. Calculate the concentration of the initial malonic acid solution. (Sec Exercise 113.)
A diprotic acid, H2B(MM=126g/moL), is determined to be a hydrate, H2B xH2O. A 10.00-g sample of this hydrate is dissolved in enough water to make 150.0 mL of solution. Twenty-five milliliters of this solution requires 48.5 mL of 0.425 M NaOH to reach the equivalence point. What is x?
A good buffer generally contains relatively equal concentrations of weak acid and conjugate base. If you wanted to buffer a solution at pH = 4.00 or pH = 10.00, how would you decide which weak acidconjugate base or weak baseconjugate acid pair to use? The second characteristic of a good buffer is good buffering capacity. What is the capacity of a buffer? How do the following buffers differ in capacity? How do they differ in pH? 0.01 M acetic acid/0.01 M sodium acetate 0.1 M acetic acid/0.1 M sodium acetate 1.0 M acetic acid/1.0 M sodium acetate
Metacresol purple is an indicator that changes from yellow to purple at pH 8.2. (a) What is Ka for this indicator? (b) What is its pH range? (c) What is the color of a solution with pH 9.0 and a few drops of metacresol purple?
Ammonia gas is bubbled into 275 mL of water to make an aqueous solution of ammonia. To prepare a buffer with a pH of 9.56, 15.0 g of NH4Cl are added. How many liters of NH3; at 25C and 0.981 atm should be used to prepare the buffer? Assume no volume changes and ignore the vapor pressure of water.
Sketch two pH curves, one for the titration of a weak acid with a strong base and one for a strong acid with a strong base. How are they similar? How are they different? Account for the similarities and the differences.
A 0.210-g sample of an acid (molar mass = 192 g/mol) is titrated with 30.5 mL of 0.108 M NaOH to a phenolphthalein end point. Is the acid monoprotic, diprotic, or triprotic?
Consider a 10.0% (by mass) solution of hypochlorous acid. Assume the density of the solution to be 1.00 g/mL. A 30.0-mL sample of the solution is titrated with 0.419 M KOH. Calculate the pH of the solution (a) before titration. (b) halfway to the equivalence point. (c) at the equivalence point.
You want to prepare a pH 4.50 buffer using sodium acetate and glacial acetic acid. You have on hand 300. mL of 0.100-M sodium acetate. Calculate the mass in grams of glacial acetic acid (d = 1.05 g/mL) you should use to prepare the buffer.
Ka for formic acid is 1.7 104 at 25C. A buffer is made by mixing 529 mL of 0.465 M formic acid, HCHO2, and 494 mL of 0.524 M sodium formate, NaCHO2. Calculate the pH of this solution at 25C after 110 mL of 0.152 M HCl has been added to this buffer.
8-94 Suppose you wish to make a buffer whose pH is 8.21. You have available 1 L of 0.100 M NaH2PO4 and solid Na2HPO4. How many grams of the solid Na2HPO4 must be added to the stock solution to accomplish this task? (Assume that the volume remains 1 L.)
The active ingredient in aspirin is acetylsalicylic acid. A 2.51-g sample of acetylsalicylic acid required 27.36 mL of 0.5106 M NaOH for complete reaction. Addition of 13.68 mL of 0.5106 M HCl to the flask containing the aspirin and the sodium hydroxide produced a mixture with pH = 3.48. Determine the molar mass of acetylsalicylic acid and its Ka value. State any assumptions you must make to reach your answer.