One of the most common antibiotics is penicillin G (benzylpenicillinic acid), which has the following structure: It is a weak monoprotic acid: HP ⇄ H + + P - k a = 1.64 × 10 − 3 where HP denotes the parent acid and P - the conjugate base. Penicillin G is produced by growing molds in fermentation tanks at 25°C and a pH range of 4.5 to 5.0. The crude form of this antibiotic is obtained by extracting the fermentation broth with an organic solvent in which the acid is soluble. (a) Identify the acidic hydrogen atom. (b) In one stage of purification, the organic extract of the crude penicillin G is treated with a buffer solution at pH = 6.50. What is the ratio of the conjugate base of penicillin G to the acid at this pH? Would you expect the conjugate base to be more soluble in water than the acid? (c) Penicillin G is not suitable for oral administration, but the sodium salt (NaP) is because it is soluble. Calculate the pH of a 0.12 A M NaP solution formed when a tablet containing the salt is dissolved in a glass of water.
One of the most common antibiotics is penicillin G (benzylpenicillinic acid), which has the following structure: It is a weak monoprotic acid: HP ⇄ H + + P - k a = 1.64 × 10 − 3 where HP denotes the parent acid and P - the conjugate base. Penicillin G is produced by growing molds in fermentation tanks at 25°C and a pH range of 4.5 to 5.0. The crude form of this antibiotic is obtained by extracting the fermentation broth with an organic solvent in which the acid is soluble. (a) Identify the acidic hydrogen atom. (b) In one stage of purification, the organic extract of the crude penicillin G is treated with a buffer solution at pH = 6.50. What is the ratio of the conjugate base of penicillin G to the acid at this pH? Would you expect the conjugate base to be more soluble in water than the acid? (c) Penicillin G is not suitable for oral administration, but the sodium salt (NaP) is because it is soluble. Calculate the pH of a 0.12 A M NaP solution formed when a tablet containing the salt is dissolved in a glass of water.
Solution Summary: The author explains how the pH of a solution is determined by the Henderson–Hasselbach equation.
One of the most common antibiotics is penicillin G (benzylpenicillinic acid), which has the following structure:
It is a weak monoprotic acid:
HP
⇄
H
+
+
P
-
k
a
=
1.64
×
10
−
3
where HP denotes the parent acid and P- the conjugate base. Penicillin G is produced by growing molds in fermentation tanks at
25°C
and a pH range of 4.5 to 5.0. The crude form of this antibiotic is obtained by extracting the fermentation broth with an organic solvent in which the acid is soluble. (a) Identify the acidic hydrogen atom. (b) In one stage of purification, the organic extract of the crude penicillin G is treated with a buffer solution at pH = 6.50. What is the ratio of the conjugate base of penicillin G to the acid at this pH? Would you expect the conjugate base to be more soluble in water than the acid? (c) Penicillin G is not suitable for oral administration, but the sodium salt (NaP) is because it is soluble. Calculate the pH of a 0.12 A M NaP solution formed when a tablet containing the salt is dissolved in a glass of water.
Phosphoric acid, H3PO4, is a triprotic acid, for which Ka1 =7.2 x 103, Ka2 = 6.3 × 10-8 and Ka3 = 4.2 x 1013.
What is the value of K for the following equation.
HPO42 (aq) + H20(1) Z H,PO4 (aq) + OH"(aq)
Express your answer in scientific notation rounded to three significant figures.
A weak acid, HA, is a monoprotic acid. A solution that is 0.140 Min HA has a pH of 1.800 at 25°C.
HA(aq) + H,0(1) 2 H;0"(aq) + A (aq)
What is the acid-ionization constant, K, for this acid?
What is the degree of ionization of the acid in this solution?
Ka-
Degree of ionization =
CH3CH2CO2H , Ką = 1.3 x 105
CH3CH2CO2 , Kp = 7.7 x 10-10
F, Kp = 1.4 x 10-11
HF , Ką = 7.2 x 10-4
For the reaction between propanoic acid (CH3CH2CO2H) and a solution containing fluoride ions (F"):
(a) The name of the conjugate base produced is
(b) The name of the conjugate acid produced is
(c) The reaction is
favoured (write 'reactant' or 'product'), because the reactants are the
(write 'weaker' or 'stronger') set of
acid and base.
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