Chapter 16, Problem 83CP

A buffer solution with it pH of 12.00 consists of Na3PO4 and Na2HPO4. The volume of solution is 200.0 mL. (a) Which component of the buffer is present in a larger amount? (b) If the concentration of Na3PO4 is 0.400 M, what mass of Na2HPO4 is present? (c) Which component of the buffer must be added to change the pH to 12.25? What mass of that component is required?

Many natural processes can be studied in the laboratory but only in an environment of controlled pH. Which of these combinations is the best to buffer the pH at approximately 7? Explain your choice. H3PO4/NaH2PO4 NaH2PO4/Na2HPO4 Na2HPO4/Na3PO4

Does the pH of the solution increase, decrease, or stay the same when you (a) Add solid sodium oxalate, Na2C2O4, to 50.0 mL of 0.015-M oxalic acid? (b) Add solid ammonium chloride to 100. mL of 0.016-M HCl? (c) Add 20.0 g NaCl to 1.0 L of 0.012-M sodium acetate, NaCH3COO?

A solution is prepared by dissolving 0.350 g of benzoic acid, HC7H5O2, in water to make 100.0 mL of solution. A 30.00-mL sample of the solution is titrated with 0.272 M KOH. Calculate the pH of the solution (a) before titration. (b) halfway to the equivalence point. (c) at the equivalence point.

Phenol, C6H5OH, is a weak organic acid. Suppose 0.515 g of the compound is dissolved in enough water to make 125 mL of solution. The resulting solution is titrated with 0.123 M NaOH. C6H5OH(aq) + OH(aq) C6H5O(aq) + H2O() (a) What is the pH of the original solution of phenol? (b) What are the concentrations of all of the following ions at the equivalence point: Na+, H3O+, OH, and C6H5O? (c) What is the pH of the solution at the equivalence point?

A buffer solution was prepared that contained 0.60 M hydrogen fluoride, HF (Ka = 7.2 x 104) and 1.00M potassium fluoride, KF. The total volume was 250 mL. (a) What ions and molecules are present in the solution? List them in order of decreasing concentration: Decreasing order of Concentration (b) What is the pH of the buffer solution described above? (c) What is the pH of 100. mL of the buffer solution if you add 100. x 10-3 g of NaOH? Assume negligible change in volume. (USEFUL INFORMATION: MM NaOH = 39.997 g mol-1)

A student was required to prepare 250.0 mL of a cyanoacetic acid/sodium cyanoacetate buffer in which the concentration of the weak acid component was 0.06 M and the concentration of the conjugate base was 0.028 M. The student was supplied with 0.512 M cyanoacetic acid and 1.0M NaOH to perform this task. What volume (in mL) of the acid would the student need to prepare this buffer solution? Hint: assume that all of the conjugate base comes directly from the reaction of NaOH with the weak acid (in other words, there is negligible dissociation of the weak acid). Please enter answers with 2 decimal places.

31. (a) Calculate the pH of a mixture containing 0.1 M propanoic acid (CH3CH₂COOH) and 0.050 M sodium propanoate (CH3CH₂COONa) (b) Determine the change in pH that occurs when 0.15 mol solid NaOH is added to 1.00 litre of the buffered solution. 32. (a) Calculate the pH of a buffer solution produced by adding 3.28 g of sodium ethanoate to 1 dm3 of 0.01 M of ethanoic acid (Ka = 1.84x 10-5 at 300K) (b) calculate the pH of this buffer if 10 cm3 of 0.1 M HCl are now added

A buffer solution is prepared by dissolving 1.000 g of sodium acetate (CH3COONA) into 100.00 mL of a 0.100 M solution of acetic acid. Then 1.80 mL of a 10.00 M solution of hydrochloric acid is added to the acetic acid/sodium acetate buffer solution. The K, of acetic acid is 1.8 × 10. What is the pH of the solution after adding HCl? pH