One way to prepare the HEPES buffer involves preparing solutions of the sodium salt form of HEPES (A) and the weak acid form of HEPES (HA) and then combining the solutions to obtain a buffer with the desired pH and concentration. CORRECT; see section 2.4 In preparing 250 mL of 1.0M stock solutions of the A and HA forms of HEPES (supplied as solids by the manufacturer with molar masses of 260.3g.mol-¹ and 238.3g.mol-¹, respectively), what masses of the acid (HA) and the conjugate base (A) would be needed? Round to the nearest whole number. mass of HA (g) = 59.58 mass of A (g) = 65.08 (Tolerance is +/- 2%) eTextbook and Media Hint X INCORRECT; see section 2.4 Calculate the volume of each stock solution needed to prepare 1.0 L of the 0.10 M HEPES buffer at a pH = 8.0. volume HA (mL) = i 100 volume A (mL) = i 100 (Tolerance is +/- 2%)

One way to prepare the HEPES buffer involves preparing solutions of the sodium salt form of HEPES (A) and the weak acid form of HEPES (HA) and then combining the solutions to obtain a buffer with the desired pH and concentration. CORRECT; see section 2.4 In preparing 250 mL of 1.0M stock solutions of the A and HA forms of HEPES (supplied as solids by the manufacturer with molar masses of 260.3g.mol-¹ and 238.3g.mol-¹, respectively), what masses of the acid (HA) and the conjugate base (A) would be needed? Round to the nearest whole number. mass of HA (g) = 59.58 mass of A (g) = 65.08 (Tolerance is +/- 2%) eTextbook and Media Hint X INCORRECT; see section 2.4 Calculate the volume of each stock solution needed to prepare 1.0 L of the 0.10 M HEPES buffer at a pH = 8.0. volume HA (mL) = i 100 volume A (mL) = i 100 (Tolerance is +/- 2%)

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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A buffer contains 0.035 mol of boric acid (pKa = 9.15) and 0.015 mol of sodium borate per liter. (a) Calculate the pH of the buffer.(b) Calculate the pH when 2.5 mL of 0.50 M HCl is added to 0.5 L of the buffer.(c) Calculate the pH when 2.5 mL of 0.50 M HCl is added to 0.5 L of pure water.
You have 1.5 liter of solution that is composed of 8.88 grams of NH3 and 11.33 grams of ammonium chloride mixed well. Kb for ammonia =1.8 x 10^-5 (A) is this a buffer solution? Why or why not? (B)if it is a buffer solution, what is the pH of this buffer solution? (C)how many mL of 1.50 M HCl can be added to this solution before the buffer is exhausted (d) how many mL of 1.5 M NaOH can be added to this solution before the buffer is exhausted?
What is the pH of a buffer prepared by mixing 5.0 g of ammonia (NH3) and 20.0 g of ammonium chloride (NH4Cl) in enough water to form 2.50L of solution. The K, of ammonia is 1.76 x 10-5. How many moles of sodium hypobromite, NaBrO, should be added to 1.00 L of 0.050 M hypobromous acid, HBrO, to form a buffer solution of pH 8.80? Assume no volume change when the NaBr is added. K. of HBrO is 2.50 x 10.⁹ How many grams of sodium lactate, NaC3H5O3, should be added to 1.00L of 0.150M lactic acid, HC3H₂O3, to form a buffer solution with a pH of 3.90? Assume no volume change when the sodium lactate is added. K. of lactic acid is 1.40 x 10-4.
A 5.145 g sample of a solid, weak, monoprotic acid is used to make a 100.0 mL solution. 27.00 mL of the resulting acid solution is then titrated with 0.09636 M NaOH. The pH after the addition of 16.00 mL of the base is 5.75, and the endpoint is reached after the addition of 45.85 mL of the base. (a) How many moles of acid were present in the 27.00 mL sample?4.42e-3 mol(b) What is the molar mass of the acid?314 g/mol(c) What is the pKa of the acid? (only confused on part c, answers for a and b are given)
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Three buffers are prepared with equal concentrations of formic acid and sodium formate (Buffer 1), hydrofluoric acid and sodium fluoride (Buffer 2), and acetic acid and sodium acetate (Buffer 3). Rank the three buffers from highest to lowest pH at which they can buffer a solution (i.e., their buffering pH).(a) 1, 2, 3(b) 3, 2, 1(c) 2, 1, 3(d) 3, 1, 2
Consider the titration of 36.0 mL of 0.117 M ammonia with 0.0752 M HCl. (See the Acid-Base Table.) (a) How many mL of HCl are required to reach the equivalence point?5.60 mL(b) What is the pH at the equivalence point? 5.30(c) What is the pH of the solution after the addition of 15.7 mL of acid? (d) What is the pH of the solution after the addition of 82.9 mL of acid? only need part c and d please
a) A student prepares an 750.0 mL buffer solution with a pH of 4.85 by adding sodium acetate to a solution of acetic acid. However, they forgot to document the mass of NaC2H3O2 added to the beaker. Fortunatelly, they know that the concentration of HC2H3O2 is 0.235M. Determine the mass, in grams, of NaC2H3O2 that must have been added to the solution. (Molar Mass of NaC2H3O2=82.0343 g/mol) b) 10 mL is accidentally spilled into the buffer solution from part a. Determing the new pH of the solution.
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A buffer contains 0.010 mol of lactic acid (pKa = 3.86) and 0.050 mol of sodium lactate per liter. (a) Calculate the pH of the buffer. (b) Calculate thechange in pH when 5 mL of 0.5 M HCl is added to 1 L of the buffer. (c) What pH change would you expect if you added the same quantity of HCl to 1 L of pure water?
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A chemistry graduate student is given 250. mL of a 1.40M ammonia (NH3) solution. Ammonia is a weak base with K-1.8x10 should the student dissolve in the NH3 solution to turn it into a buffer with pH = 9.17? What mass of NH, Br You may assume that the volume of the solution doesn't change when the NH4Br is dissolved in it. Be sure your answer has a unit symbol, and round it to 2 significant digits. ?