Tris(hydroxymethyl)aminomethane [(HOCH2)3CNH2, or "Tris" for short] acts as a Brønsted- Lowry base (pK, = 5.92 at 25°C). Tris and TrisHCI are often combined to make a buffer in biochemical laboratories. %3D (a) At what pH do Tris buffers behave optimally (i.e., have equal capacity to neutralize acid and base additions)? (b) Tris buffer is normally used between pH values of 7.0 and 9.0. Calculate the ratio [Tris]/[TrisH+] at the extremes of the range. (c) A buffer is prepared by diluting 50.0 g Tris base and 65.0 g TrisHCI to a total volume of 2.0 L. What is the pH of the buffer? (d) What is the pH after 0.50 mL of 12 M HCI is added to a 200.0-mL portion of the buffer in part (c)?

Tris(hydroxymethyl)aminomethane [(HOCH2)3CNH2, or "Tris" for short] acts as a Brønsted- Lowry base (pK, = 5.92 at 25°C). Tris and TrisHCI are often combined to make a buffer in biochemical laboratories. %3D (a) At what pH do Tris buffers behave optimally (i.e., have equal capacity to neutralize acid and base additions)? (b) Tris buffer is normally used between pH values of 7.0 and 9.0. Calculate the ratio [Tris]/[TrisH+] at the extremes of the range. (c) A buffer is prepared by diluting 50.0 g Tris base and 65.0 g TrisHCI to a total volume of 2.0 L. What is the pH of the buffer? (d) What is the pH after 0.50 mL of 12 M HCI is added to a 200.0-mL portion of the buffer in part (c)?

Principles of Modern Chemistry

8th Edition

ISBN:9781305079113

Author:David W. Oxtoby, H. Pat Gillis, Laurie J. Butler

Publisher:David W. Oxtoby, H. Pat Gillis, Laurie J. Butler

Chapter15: Acid–base Equilibria

Section: Chapter Questions

Problem 92AP

See similar textbooks

Similar questions

) A truck driver carrying a load of lead nitrate (Pb(NO3)2) lost control of his semi- truck after hitting a patch of ice and crashed the truck into Blue Lake, which was right next to the highway. Despite the best efforts of the emergency workers, several of the crates containing lead nitrate were damaged, and the highly soluble compound dissolved immediately. Assuming the lake is initially at circumneutral pH (7), and that the spill resulted the in a total lead concentration of 10-3 M within the lake. Based on the following information, will PbO(s) precipitate out of Blue Lake. Assume all lead nitrate dissociates into Pb+2 and NO3-, no other sources of lead exist in the lake and that no other reactions besides the equations shown below occur. PbO(s) + 2H+ ⇌ PbO(s) + H+ ⇌ PbO(s) + H2O ⇌ PbO(s) + 2H2O ⇌ Pb2+ + H2O PbOH+ + H2O Pb(OH)2o Pb(OH)3- + H+ logKs0/ksp =14 logK1=3.4 logK2=-0.5 logK3=-12
a) At temperature 25°C, 0.02 M hydrazine, N2H4 solution is 0.69% ionised. Calculate the i. Concentration of OH- ion ii. ionisation constant, Kb b) Calculate the mass of sodium benzoate, C6H5COONa that should be added to 500 mL of 0.2M aqueous benzoic acid, C6H5COOH solution to produce a buffer with pH 3.50?[ Ka for C6H5COOH = 6.3 x10-5] c) When a 1 x 10-3 moldm-3 solution of CaCl2 is mixed with an equal volume of a 1 x 10-3 moldm-3 solution of Na2SO4, will precipitate form? (Ksp CaSO4= 2 x 10-5) Do you mean that pH? That was all the given information the question gave.. I don't understand how to use the ionised part the most
b. A student has a sea water sample which contains Ca2+ ions . Describe briefly how he willdetermine the concentration of Ca2+ ion in the sample using a simple titration. Explain the colourchanges at the endpoint. Which medium is suitable for performing the titration, acidic or basic medium and why?
In Protein Precipitation, two liters of 5mM buffer solution with pH 5.2 is needed in the isolation of albumin. Calculate and measure the amounts (in grams if solid and in mL if liquid) of weak acid and conjugate base needed to be able to prepare the chosen buffer system in part A above. Express your answer in useful units (that is, prepare it from practical amounts or concentrations of starting materials). Pls. show the step by step process on solving the problem.
A microbiologist is preparing a medium on which to cultureE. colibacteria. She buffers the medium at pH 7.00 to minimize the effect of acid-producing fermentation. What volumes ofequimolar aqueous solutions of K₂HPO₄and KH₂PO₄must shecombine to make 100. mL of the pH 7.00 buffer?
In some water softening operations, Mg2+ must be removed from solution along with Ca2+. What is the minimum pH required to lower TOTMg to 10 mg/L as CaCO3 by precipitation of Mg(OH)2(s)?
The Ka values for nitrous acid (HNO2) and hypochlorous (HClO) acid are 4.5 x10-4and 3.0 x10-8, respectively. Which one would be more suitable for use in asolution buffered at pH = 7.0? What other substances would be needed to makethe buffer?
1. Describe the amount of reagents and steps needed for the preparation of 100 mL 0.050 M and 0.0050 M Phosphate buffers, both at pH 6.50 using: a. 0.50 M stock Phosphate Buffer solution b. Solid NaH2PO4 · 2H2O and solid Na2HPO4 · 2H2O 2. Write the balanced net ionic equation describing the phosphate buffer system.
2. You are studying an unusual enzyme that produces hydronium ions (H3O+) during the courseof the reaction.You wish to maintain pH = 8.5 for the enzyme-catalyzed reaction. Which weak acid will serveas the better 0.1 M buffer for the reaction: HEPPS with pKa = 8.0, or, AMPSO with pKa = 9.0?Justify your answer by describing how the buffer “resists” change in pH and the chemical logicof why you chose the buffer you did.
One drop, 0.200 cm3, of 1.00 mol dm-3 of aqueous sodium hydroxide, NaOH, solution is added to 25.0 cm3 of a phosphate buffer that is 0.040 mol dm-3 in KH2PO4(aq) and 0.020 mol dm-3 in K2HPO4(aq). Calculate the resulting pH of the solution given that the second acid dissociation constant, pKa2, for phosphoric acid is 7.21.
The Henderson-Hasselbalch equation: a. relates the pH of a solution to the pKa and the concentration of acid and salt. b. allows the graphical determination of the molecular weight of a weak acid from its pH alone. c. is equally useful with solutions of acetic acid and of hydrochloric acid. d. employs the same value for pKa for all weak acids.
What mass (in grams) of sodium acetate (CH3COONa) must be added to 100.00 mL of a 0.115 M solution of acetic acid in order to prepare a buffer solution with a pH of 4.70? The Ka of acetic acid is 1.8 × 10−5. Mass of sodium acetate =