Pearson eText Organic Chemistry -- Instant Access (Pearson+)
8th Edition
ISBN: 9780135213711
Author: Paula Bruice
Publisher: PEARSON+
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Textbook Question
Chapter 2.10, Problem 43P
A naturally occurring amino acid such as alanine has a group that is a
- a. If the pKa value of a carboxylic add such as acetic acid is about 5 (see Table 2.1 ), then why is the pKa value of the carboxylic acid group of alanine so much lower?
- b. Draw the structure of alanine in a solution at pH = 0.
- c. Draw the structure of alanine in a solution at physiological pH (pH 7.4).
- d. Draw the structure of alanine in a solution at pH = 12.
- e. Is there a pH at which alanine is uncharged (that is. neither group has a charge)?
- f. At what pH does alanine have no net charge (that is, the amount of negative charge is the same as the amount of positive charge)?
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Two pKa values are reported for malonic acid, a compound with twoCOOH groups. Explain why one pKa is lower and one pKa is higher thanthe pKa of acetic acid (CH3COOH, pKa = 4.8).
A naturally occurring amino acid such as alanine has a group that is a carboxylic acid and a group that is a protonated amine. The pKa values of the two groups are shown.(a). If the pKa value of a carboxylic acid such as acetic acid is about 5, then why is the pKa value of the carboxylic acid group of alanine so much lower? (b). Draw the structure of alanine in a solution at pH = 0.
(c). Draw the structure of alanine in a solution at physiological pH (pH 7.4).(d). Draw the structure of alanine in a solution at pH = 12.
(e). Is there a pH at which alanine is uncharged (that is, neither group has a charge)?
(f) At what pH does alanine have no net charge (that is, the amount of negative charge is the same as the amount of positive charge)?
a) Calculate Ka of formic acid whose pKa= 3.75.
b) Calculate pKa of nitromethane whose Ka= 5.0 x 10"
Chapter 2 Solutions
Pearson eText Organic Chemistry -- Instant Access (Pearson+)
Ch. 2.1 - Which of the following are not acids? CH3COOH CO2...Ch. 2.1 - Consider the following reaction: a. What is the...Ch. 2.1 - Draw the products of the addbase renc1 ion when a....Ch. 2.1 - a. What is the conjugate acid of each or the...Ch. 2.2 - a. Which is a stronger acid: one with a pKa of 5.2...Ch. 2.2 - An acid has a Ka of 4.53 106 in water. What is...Ch. 2.2 - Prob. 7PCh. 2.2 - Antacids are compounds that neutralize stomach...Ch. 2.2 - Are the following body fluids acidic or basic? a....Ch. 2.3 - Draw the conjugate acid of each of the following:...
Ch. 2.3 - a. Write an equation showing CH3OH reacting as an...Ch. 2.3 - Estimate the pKa values of the following...Ch. 2.3 - a. Which is a stronger base: CH3COO or HCOO? (The...Ch. 2.3 - Using the pKa values in Section 2.3, rank the...Ch. 2.4 - Prob. 15PCh. 2.5 - a. For each of the acid-base reactions in Section...Ch. 2.5 - Ethyne has a pKa value of 25, water has a pKa...Ch. 2.5 - Which of the following bases can remove a proton...Ch. 2.5 - Calculate the equilibrium constant for the...Ch. 2.6 - Rank the ions (CH3, NH2, HO, and F) from most...Ch. 2.6 - Rank the carbanions shown in the margin from most...Ch. 2.6 - Which is the stronger acid?Ch. 2.6 - Prob. 23PCh. 2.6 - What reaction in Problem 23 has the smallest...Ch. 2.6 - Rank the halide ions (F, Cl, Br, and l) from...Ch. 2.6 - a. Which is more electronegative, oxygen or...Ch. 2.6 - Which is a stronger acid? a. HCl or HBr b....Ch. 2.6 - a. Which of the halide ions (F, Cl, Br, and l) is...Ch. 2.6 - Which is a stronger base? (The potential maps in...Ch. 2.7 - What is a stronger acid? a. CH3OCH2CH2OH or...Ch. 2.7 - Rank the following compounds from strongest add to...Ch. 2.7 - What is a stronger base?Ch. 2.8 - For each of the following compounds, indicate the...Ch. 2.8 - Prob. 35PCh. 2.8 - Which is a stronger acid? Why?Ch. 2.8 - Fosamax (shown on the previous page) has six...Ch. 2.9 - Using the table of pKa values given in Appendix I,...Ch. 2.10 - For each of the following compounds (here shown in...Ch. 2.10 - As long as the pH is not less than _______, at...Ch. 2.10 - a. Indicate whether a protonated amine (RN+H3)...Ch. 2.10 - A naturally occurring amino acid such as alanine...Ch. 2.10 - a. At what pH is the concentration of a compound,...Ch. 2.10 - For each of the following compounds, indicate the...Ch. 2.10 - Given the data in Problem 47: a. What pH would you...Ch. 2.11 - Write the equation that shows how a buffer made by...Ch. 2.12 - Draw the products of the following react ions. Use...Ch. 2.12 - What product are formed when each of the following...Ch. 2 - Which is a stronger base? a. HS or HO b. CH3O or...Ch. 2 - According to the explanations by Lewis, if a...Ch. 2 - a. Rank the following alcohols from strongest to...Ch. 2 - a. Rank the following carboxylic acids from...Ch. 2 - Prob. 57PCh. 2 - For the following compound. a. draw its conjugate...Ch. 2 - Rank the following compounds from strongest to...Ch. 2 - Prob. 60PCh. 2 - Prob. 61PCh. 2 - a. Rank the following alcohols from strongest to...Ch. 2 - A single bond between two carbons with different...Ch. 2 - For each compound, indicate the atom that is most...Ch. 2 - a. Given the Ka values, estimate the pKa value of...Ch. 2 - Tenormin, a member of the group of drugs known as...Ch. 2 - From which of the following compounds can HO...Ch. 2 - a. For each of the following pairs of reactions,...Ch. 2 - Prob. 69PCh. 2 - Which is a stronger acid? a. b. c. d.Ch. 2 - Prob. 71PCh. 2 - Prob. 72PCh. 2 - Given that pH+ pOH = 14 and that the concentration...Ch. 2 - How could you separate a mixture of the following...Ch. 2 - Prob. 75PCh. 2 - a. If an add with a pKa of 5.3 is in an aqueous...Ch. 2 - Calculate the pH values of the following...Ch. 2 - Prob. 1PCh. 2 - Prob. 2PCh. 2 - Prob. 3PCh. 2 - Which of the reactions in Problem 3 favor...Ch. 2 - Prob. 5PCh. 2 - Prob. 6PCh. 2 - Prob. 7PCh. 2 - Which is the stronger acid? a. ClCH2CH2OH or...Ch. 2 - Prob. 9PCh. 2 - Prob. 10PCh. 2 - Which is a more stable base? Remembering that the...Ch. 2 - Which is the Stronger acid?Ch. 2 - Prob. 13PCh. 2 - a. Draw the structure of (CH3COOH (pKa = 4.7) at...
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- d. The Ka of acetic acid (found in vinegar) is 1.8×10-5. Then the pKa of formic acid isarrow_forwardThe pKa for Molecule A is 10 units lower than Molecule B. Molecule A Draw conjugate base of A :B H H pKa = 10 Molecule B Draw conjugate base of B OCH3 :B H H pКa 3 20 Please provide a brief explanation for the difference in pKa of these to molecules.arrow_forwardMatch the pKa values to the appropriate compound. pKa values: 0.28, 1.24, 2.66, 2.86, and 3.12. Compounds: (a) FCH2COOH; (b) CF3COOH; (c) F2CHCOOH; (d) ICH2COOH; (e) BrCH2COOH.arrow_forward
- a If an acid, HA, dissolves in water such that the Ka is 10000, what is the pK, of that acid? pK :arrow_forwardWhich of the following explains why alpha-amino acids, the building blocks of proteins, are nearly 1000 times more acidic than aliphatic carboxylic acids? H3N. R. An a-amino acid An aliphatic acid pK, 5 pKa = 2 O Inductive effects of the aliphatic group destabilize the conjugate base. O Inductive effects of the amino group help stabilize the conjugate base. O Inductive effects of the aliphatic groups help stbilize the conjugate base. O Inductive effects of the amino group destabilize the conjugate base.arrow_forward2. What are the pKa's of HCN (hydrocyanic acid), and HF (hydrofluoric acid)? Based only on those pka values, what do you expect to be the products of the reaction below? Briefly explain. HCN+HF->?arrow_forward
- Why are the carboxylic acid groups of the amino acids so much more acidic (pK a ~ 2) thana carboxylic acid such as acetic acid (pKa = 4.76)?arrow_forwardWhy are the carboxylic acid groups of the amino acids more acidic (pKa - 2) than a carboxylic acid such as acetic acid (pKa = 4.76)?arrow_forwardConsidering the following table of pK, values. pKa values of organic and inorganic acids Acid pKa pKa CH3 CH3 51 7.04 NH3 38 6.36 H₂ 35 4.76 CH3 CH₂OH 15.9 C6H5 COOH 4.19 H₂O 15.7 H3O+ -1.74 CH, OH 15.50 H₂SO4 -5.2 CH, NH3 + -3 10.64 HBr -8 NH₁+ 9.24 Acid ● H₂S H₂CO3 CH,COOH Between the two compounds, OH or CH3 CH₂, draw the Lewis structure of the stronger base. • Draw all atoms, including hydrogen atoms. Apply formal charges where appropriate. ● › Assign lone pairs and radical electrons where appropriate. Sn [Farrow_forward
- 3. Rank the following acids in order from strongest to weakest.HA (pKa = 2.55) H2Z (pKa1 = 4.35) H3X (pKa1 = 3.17) HY (pKa = 5.72) 4. Rank each base in order from strongest to weakest.B (pKb = 4.12) Y– (pKa = 5.72 for conjugate acid) A– (pKa = 2.55 for conjugate acid)E (pKb = 8.12)arrow_forwardTwo pKa values are reported for malonic acid, a compound with two COOH groups. Explain why one pKa is lower and one pKa is higher than the pKa of acetic acid (CH3COOH, pKa = 4.8).arrow_forward3. Which is the stronger acid: (a) Benzoic acid with a Ka of 6.5 x10-5 or hydrocyanic acid with a Ka of 4.9 x 10-10? (b) Boric acid with a pKa of 9.14 or carbonic acid with a pKa of 6.37arrow_forward
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