- (a) Suppose you wanted to make a buffer of exactly pH 7.00 using KH,PO, and Na,HPO,. If the final solution was 0.1 M in KH,PO,, what concentration of Na,HPO, would you need? (b) Now assume you wish to make a buffer at the same pH, using the same substances, but want the total phosphate molarity ([HPO,²]+ [H;PO, ]) to equal 0.3. What concentrations of the KH,PO4 and Na;HPO, would be required?

- (a) Suppose you wanted to make a buffer of exactly pH 7.00 using KH,PO, and Na,HPO,. If the final solution was 0.1 M in KH,PO,, what concentration of Na,HPO, would you need? (b) Now assume you wish to make a buffer at the same pH, using the same substances, but want the total phosphate molarity ([HPO,²]+ [H;PO, ]) to equal 0.3. What concentrations of the KH,PO4 and Na;HPO, would be required?

Chemistry: Principles and Reactions

8th Edition

ISBN:9781305079373

Author:William L. Masterton, Cecile N. Hurley

Publisher:William L. Masterton, Cecile N. Hurley

Chapter15: Complex Ion And Precipitation Equilibria

Section: Chapter Questions

Problem 14QAP: A buffer solution is prepared by adding 5.50 g of ammonium chloride and 0.0188 mol of ammonia to...

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A 10.00-g sample of the ionic compound NaA, where A is the anion of a weak acid, was dissolved in enough water to make 100.0 mL of solution and was then titrated with 0.100 M HCl. After 500.0 mL HCl was added, the pH was 5.00. The experimenter found that 1.00 L of 0.100 M HCl was required to reach the stoichiometric point of the titration. a. What is the molar mass of NaA? b. Calculate the pH of the solution at the stoichiometric point of the titration.
A chemistry graduate student is given 125. mL of a 1.50M diethylamine ((C,H, NH solution. Diethylamine is a weak base with K,=1.3 × 10 °. What mass (HIN %3D of (C,H5), NH,Br should the student dissolve in the (C,H,) NH solution to turn it into a buffer with pH =10.79? 2. You may assume that the volume of the solution doesn't change when the (C,H) NH, Br is dissolved in it. Be sure your answer has a unit symbol, and round 12 it to 2 significant digits. 10
22. Which of the following will give a buffer solution when equal volumes of the two solutions are mixed? (a) 0.10 M HNO, and 0.10 M NaNO, ( b) 0.10 M HC,H,O, and 0.10 M Nac,H,O, (c) 0.10 M HC,H;O, and 0.20 M NaOH (d) 0.10 M HI and 0.20 M NaBr
Ammonia is a convenient buffer system in the slightly basic range. (a) What is the pH of a buffer solution containing 49 g of NH,CI dissolved in 1.00 L of 0.919 M NH3? pH = (b) How many moles of acid are required to change the pH of this solution by 0.05 pH units? mol (c) Suppose 4.6 mL of 12.6 M HCI solution is added to 471 ml of the solution of Part (a). Calculate the new pH. pH =
(a). Calculate the pH of a buffer solution containing 0.30 mole of KF and 0.40 mol of HF in 1.0 liter solution. (Ka of HF is 7.2*10–4); 20.0 mL of 1.50 M NaOH is added to the original buffer in question (a). (b) Show the equation of reaction which take place when NaOH is added. (c) What will the pH of the buffer solution in question (a) be after the addition of 20.0 mL of 1.50 M NaOH.
Which of the following gives a buffer solution when equal volumes of the two solutions are mixed? (a) 0.10 M NH; and 0.10 M HCI (b) 0.20 М NH; and 0.10 M НСІ (c) 0.10 M NH,Cl and 0.10 M NH3 (d) 0.20 M NH,Cl and 0.10 M NAOH Which of the following solutions has the greater buffer сараcity: 100 mL of 0.30 M HNO2-0.30 M NaNO2 or 100 mL of 0.10 M HNO2-0.10 M NaNO2? Explain. Calculate the concentrations of NH4* and NH3 and the pH in a solution prepared by mixing 20.0 g of NaOH and 0.500 L of 1.5 M NH,CI. Assume that the volume remains constant.
How many grams of NH,Cl would have to be added to 250.0 mL of a 0.420 M NH3 solution to prepare a buffer solution with a pH of 10.0? pK, = 9.25 for NH4* mass of NH,Cl (g):
11 (a) Define a buffer solution (b) What are the components of (i) an acidic buffer ? (ii) a basic buffer ?
1.00 L of a buffer is made up of 0.15 M HCN(aq) with 0.25 M NaCN(aq). Ka(HCN)=6.2x10-10. (A) What is the pH of this buffer solution? [Select] (B) What is the pH after 0.10 mole of HCI is added to this buffer solution? [Select] (C) What is thee pH after 0.05 mole of NaOH is added to this buffer solution? [Select]
A buffer solution contains 0.21 mol of propionic acid (HC Hs02) and 0.65 mol of sodium propionate (NacaH5O2) in 7.70 L. The K, of propionic acid (HC3HsO2) is Ka = 1.3e-05. !! (a) What is the pH of this buffer? pH = (b) What is the pH of the buffer after the addition of 0.09 mol of NaOH? (assume no volume change) pH = (c) What is the pH of the original buffer after the addition of 0.44 mol of HI? (assume no volume change) pH =
17.
(a) Write the net ionic equation for the reaction that occurswhen a solution of hydrochloric acid (HCl) is mixed with asolution of sodium formate (NaCHO2). (b) Calculate theequilibrium constant for this reaction. (c) Calculate theequilibrium concentrations of Na+, Cl-, H+, CHO2-, andHCHO2 when 50.0 mL of 0.15 M HCl is mixed with 50.0 mLof 0.15 M NaCHO2.