You have a 16 mL sample of acetylcholine (a neurotransmitter) with an unknown concentration and a pH of 7.66. You incubate his sample with the enzyme acetylcholinesterase to convert all of the acetylcholine to choline and acetic acid. The acetic acid issociates to yield acetate and hydrogen ions. At the end of the incubation period, you measure the pH again and find that it has ecreased to 5.52. Assuming there was no buffer in the assay mixture, determine the number of nanomoles of acetylcholine in he original 16 mL sample. CH,—C−O−CH,—CH,—*N–CH, Acetylcholine CH₂ acetycholine in original sample: CH₂ H₂O CH₂ I HO–CH,—CH,−*N−CH, + CH,-C−o + H Choline I CH3 Acetate nmol

You have a 16 mL sample of acetylcholine (a neurotransmitter) with an unknown concentration and a pH of 7.66. You incubate his sample with the enzyme acetylcholinesterase to convert all of the acetylcholine to choline and acetic acid. The acetic acid issociates to yield acetate and hydrogen ions. At the end of the incubation period, you measure the pH again and find that it has ecreased to 5.52. Assuming there was no buffer in the assay mixture, determine the number of nanomoles of acetylcholine in he original 16 mL sample. CH,—C−O−CH,—CH,—N–CH, Acetylcholine CH₂ acetycholine in original sample: CH₂ H₂O CH₂ I HO–CH,—CH,−N−CH, + CH,-C−o + H Choline I CH3 Acetate nmol

Chemistry: The Molecular Science

5th Edition

ISBN:9781285199047

Author:John W. Moore, Conrad L. Stanitski

Publisher:John W. Moore, Conrad L. Stanitski

Chapter15: Additional Aqueous Equilibria

Section: Chapter Questions

Problem 17QRT: Without doing calculations, determine the pH of a buffer made front equimolar amounts of these...

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Without doing calculations, determine the pH of a buffer made front equimolar amounts of these acid-base pairs. (a) Phosphoric acid and sodium dihydrogen phosphate (b) Sodium monohydrogen phosphate and sodium dihydrogen phosphate (c) Sodium phosphate and sodium monohydrogen phosphate
Write the chemical equilibrium and expression for the equilibrium constants for the ionization of (a) tartaric acid. (b) malic acid.
Explain why even though an aqueous acetic acid solution contains acetic acid and acetate ions, it cannot be a buffer.
You have a 18 mL sample of acetylcholine (a neurotransmitter) with an unknown concentration and a pH of 7.82. You incubate this sample with the enzyme acetylcholinesterase to convert all of the acetylcholine to choline and acetic acid. The acetic acid dissociates to yield acetate and hydrogen ions. At the end of the incubation period, you measure the pH again and find that it has decreased to 5.66. Assuming there was no buffer in the assay mixture, determine the number of nanomoles of acetylcholine in the original 18 mL sample. Tip: your answer should have two significant digits! Only the mantissa (the digits to the right of the decimal) are significant when you raise a decimal number to a power. CH,—C−O−CH,—CH,—*N—CH, Acetylcholine CH 3 acetycholine in original sample: CH3 H₂O CH3 HO–CH,—CH,—*N–CH, + CH, Choline CH3 CH, T Acetate O + H+ nmol
You have a 12 mL sample of acetylcholine (a neurotransmitter) with an unknown concentration and a pH of 8.14. You incubate this sample with the enzyme acetylcholinesterase to convert all of the acetylcholine to choline and acetic acid. The acetic acid dissociates to yield acetate and hydrogen ions. At the end of the incubation period, you measure the pH again and find that it has decreased to 6.55. Assuming there was no buffer in the assay mixture, determine the number of nanomoles of acetylcholine in the original 12 mL sample. Acetycholine in original sample:________ nmol
You have a 18 mL sample of acetylcholine (a neurotransmitter) with an unknown concentration and a pH of 8.35. You incubate this sample with the enzyme acetylcholinesterase to convert all of the acetylcholine to choline and acetic acid. The acetic acid dissociates to yield acetate and hydrogen ions. At the end of the incubation period, you measure the pH again and find that it has decreased to 6.03. Assuming there was no buffer in the assay mixture, determine the number of nanomoles of acetylcholine in the original 18 mL sample.
You have a 15 mL sample of acetylcholine (a neurotransmitter) with an unknown concentration and a pH of 8.06. You incubate this sample with the enzyme acetylcholinesterase to convert all of the acetylcholine to choline and acetic acid. The acetic acid dissociates to yield acetate and hydrogen ions. At the end of the incubation period, you measure the pH again and find that it has decreased to 5.91. Assuming there was no buffer in the assay mixture, determine the number of nanomoles of acetylcholine in the original 15 mL sample. O= CH3 Acetylcholine H₂O CH,—C−O−CH,—CH,—*N-CH, → HO−CH,—CH,—*N–CH, + CH,—C−O + H* CH3 CH 3 Choline CH3 Acetate
You have a 20 mL sample of acetylcholine (a neurotransmitter) with an unknown concentration and a pH of 8.17. You incubate this sample with the enzyme acetylcholinesterase to convert all of the acetylcholine to choline and acetic acid. The acetic acid dissociates to yield acetate and hydrogen ions. At the end of the incubation period, you measure the pH again and find that it has decreased to 6.70. Assuming there was no buffer in the assay mixture, determine the number of nanomoles of acetylcholine in the original 20 mL sample. -Å-—•- CH,—C−O−CH,—CH,—*N–CH, Acetylcholine CH₂ acetycholine in original sample: CH₂ H₂O CH₂ I HO–CH,—CH,—*N–CH, + CH Choline CH₂ CHO Acetate H* nmol
You have a 11 mL sample of acetylcholine (a neurotransmitter) with an unknown concentration and a pH of 8.22. You incubate this sample with the enzyme acetylcholinesterase to convert all of the acetylcholine to choline and acetic acid. The acetic acid dissociates to yield acetate and hydrogen ions. At the end of the incubation period, you measure the pH again and find that it has decreased to 6.62. Assuming there was no buffer in the assay mixture, determine the number of nanomoles of acetylcholine in the original 11 mL sample. CH,—C−O−CH,—CH,—*N-CH, Acetylcholine CH3 acetycholine in original sample: I CH₂ H₂O CH₂ HO–CH,—CH,—*N–CH, + CH,-C−O + H* CH₂-8-0 Choline | CH3 Acetate nmol
The concentration of acetylcholine (a neurotransmitter) in a sample can be determined from the pH changes that accompany its hydrolysis. When the sample is incubated with the enzyme acetylcholinesterase, acetylcholine is converted to choline and acetic acid, which dissociates to yield acetate and a hydrogen ion. CНз CHз Нао — сHz— CH "N— снз но-сн— сH,-"N-CH; + CH;— с-о+ н* CH3-C-0- сHз CHз Choline Acetylcholine Acetate In a typical analysis, 11 mL of an aqueous solution containing an unknown amount of acetylcholine had a pH of 7.70. When incubated with acetylcholinesterase, the pH of the solution decreased to 6.89. Assuming there was no buffer in the assay mixture, determine the number of moles of acetylcholine in the 11 mL sample.
In the laboratory, a general chemistry student measured the pH of a 0.509 M aqueous solution of phenol (a weak acid), CGH5OH to be 5.162. Use the information she obtained to determine the K, for this acid. K„(experiment) =
7. A common buffer solution can be prepared by using ammonia and ammonium salts. The base equilibrium constant of ammonia, NH3, is 1.815x10-5 A student worker is asked to prepare a buffer solution with NH3 and ammonium salt. However, after the student did a thorough search, no ammonium salt is found. After the student reported the result to the professor, the professor told the student the buffer can be prepared with ammonia and a strong acid. Can you help this student out? The pH of the buffer to be prepared is 10.08. The molarity of the ammonia in the buffer is 0.4717 M. The molarity of the ammonia solution found in the laboratory is 1.201 M, the strong acid solution is 0.9948 M HNO3. The volume of the buffer solution to be prepared is 500.0 mL. Please answer the following questions. A. B. What is the molarity of the ammonium ion in the buffer? Please provider your answer below. Check answer How many mL of 0.9948 M HNO3 solution is needed? Please provider your answer below. 0² 0₂ $…