Be sure to answer all parts. A microbiologist is preparing a medium on which to culture E. coli bacteria. She buffers the medium at pH 7.00 to minimize the effect of acid-producing fermentation. What volumes of equimolar aqueous solutions of K2HPO, and KH,PO, must she combine to make 900.0 mL of the pH 7.00 buffer? K, values for phosphoric acid: Ka1 = 7.2 x 103 K22 = 6.3 x 10-8 Ka3 = 4.2 x 10-13 Volume H,PO, = | mL Volume HPO,: mL

Be sure to answer all parts. A microbiologist is preparing a medium on which to culture E. coli bacteria. She buffers the medium at pH 7.00 to minimize the effect of acid-producing fermentation. What volumes of equimolar aqueous solutions of K2HPO, and KH,PO, must she combine to make 900.0 mL of the pH 7.00 buffer? K, values for phosphoric acid: Ka1 = 7.2 x 103 K22 = 6.3 x 10-8 Ka3 = 4.2 x 10-13 Volume H,PO, = | mL Volume HPO,: mL

Chemistry: An Atoms First Approach

2nd Edition

ISBN:9781305079243

Author:Steven S. Zumdahl, Susan A. Zumdahl

Publisher:Steven S. Zumdahl, Susan A. Zumdahl

Chapter14: Acid- Base Equilibria

Section: Chapter Questions

Problem 4RQ: A good buffer generally contains relatively equal concentrations of weak acid and conjugate base. If...

See similar textbooks

Similar questions

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
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.)
Fifty cm3 of 1.000 M nitrous acid is titrated with 0.850 M NaOH. What is the pH of the solution (a) before any NaOH is added? (b) at half-neutralization? (c) at the equivalence point? (d) when 0.10 mL less than the volume of NaOH to reach the equivalence point is added? (e) when 0.10 mL more than the volume of NaOH to reach the equivalence point is added? (f) Use your data to construct a plot similar to that shown in Figure 14.10 (pH versus volume NaOH added).
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.
A biochemist needs 750 mL of an acetic acid–sodiumacetate buffer with pH 4.50. Solid sodium acetate(CH3COONa) and glacial acetic acid (CH3COOH) areavailable. Glacial acetic acid is 99% CH3COOH by massand has a density of 1.05 g/mL. If the buffer is to be 0.15 Min CH3COOH, how many grams of CH3COONa and howmany milliliters of glacial acetic acid must be used?
If 40.0 mL of formic acid with a concentration of 0.300 M and a Ka of (2.258x10^-5) is titrated with 0.300 M lithium hydroxide what is the pH of the solution after 20.00 ml of base has been added? Note: Your answer is assumed to be reduced to the highest power possible.
You are to prepare 100. mL of an acetate buffer of pH 5.00 using 1.0 M acetic acid (CH3CO2H, also written as HC2H3O2) and solid sodium acetate (NaC2H3O2). To prepare for the investigation, complete the following calculations. The pKa for HC2H3O2 is 4.74. The Henderson-Hasselbach equation is pH = pKa + log ([conjugate base]/[acid]) (a) What ratio of [NaC2H3O2] to [CH3CO2H] is required for a pH = 5.00? (b) You will want the concentrations relatively dilute, so use an acid concentration of 0.10 M. What volume of 1.0 M CH3CO2H would be needed to prepare 100. mL of buffer with the desired concentration of 0.10 M? Use M1V1 = M2V2 (c) Use the ratio from (a) and the concentration desired (discussed in (b)) to calculate how many grams of NaC2H3O2 · 3 H2O would be needed to prepare 100. mL of buffer if the acid concentration is 0.10 M?
What volumes of equimolar aqueous solutions of K2HPO4 and KH2PO4 must she combine to make 600.0 mL of the pH 7.00 buffer? Ka values for phosphoric acid: Ka1 = 7.2 ×10−3 Ka2 = 6.3 ×10−8 Ka3 = 4.2 ×10−13
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?
Magnesium carbonate is slightly soluble in water. The Ksp for MgCO3 is 3.5 x 10-8. The carbonate ion being a conjugate base may form the bicarbonate ion (HCO3-) and carbonic acid (H2CO3) in solution. Which of the following represents the correct mass balance equation at a pH of 7.5 for this system?
You are asked to prepare a buffer solution with pH 5.10. If you start with a solution containing 10.0 mmol acetic acid (CH3COOH, Ka = 1.8×10-5), how many millimoles of sodium acetate (CH3COONa) must be added to the solution?Express your answer to three significant figures. mmol CH3COONa Part B: What volume of 0.150 M sodium acetate would be required to get the number of mmol in Part A?Express your answer to three significant figures. V = mL
Consider how best to prepare one liter of a buffer solution with pH = 3.79 using one of the weak acid/conjugate base systems shown here. Weak Acid Conjugate Base Ka pKa HC2O4- C2O42- 6.4 x 10-5 4.19 H2PO4- HPO42- 6.2 x 10-8 7.21 HCO3- CO32- 4.8 x 10-11 10.32 How many grams of the sodium salt of the weak acid must be combined with how many grams of the sodium salt of its conjugate base, to produce 1.00 L of a buffer that is 1.00 M in the weak base?grams sodium salt of weak acid = grams sodium salt of conjugate base =