3. Consider the following acids Acid Acetic Acid, H CCO-H Trichloroacetic Acid, Cl-CCO,H Dichloroacetic Acid, Cl-HCCO,H Chloroacetic Acid, CIH;CCO,H K, 1.8 x 10 2.2 x 10 4.5 x 10 1.4 x 10 Determine the pK, of each acid and arange them in order of decreasing acid strength.

3. Consider the following acids Acid Acetic Acid, H CCO-H Trichloroacetic Acid, Cl-CCO,H Dichloroacetic Acid, Cl-HCCO,H Chloroacetic Acid, CIH;CCO,H K, 1.8 x 10 2.2 x 10 4.5 x 10 1.4 x 10 Determine the pK, of each acid and arange them in order of decreasing acid strength.

Macroscale and Microscale Organic Experiments

7th Edition

ISBN:9781305577190

Author:Kenneth L. Williamson, Katherine M. Masters

Publisher:Kenneth L. Williamson, Katherine M. Masters

Chapter41: Acetylsalicylic Acid (aspirin)

Section: Chapter Questions

Problem 1Q

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The hydrogen phthalate ion, C8HsO4, is a weak acid with Ka = 3.91 106. C8H5O4(aq)+H2O(l)C8H4O42(aq)+H3O+(aq) What is the pH of a 0.050 M solution of potassium hydrogen phthalate. KC8H5O4? Note: To find the pH for a solution of the anion, we must take into account that the ion is amphiprotic. It can be shown that, for most cases of amphiprotic ions, the H3O+ concentration is [H3O+]=Ka1Ka2 For phthalic acid, C8H6O4 is Ka1 is 1.12 103, and Ka2 is 3.91 106.
Weak base B has a pKb of 6.78 and weak acid HA has a pKa of 5.12. a Which is the stronger base, B or A? b Which is the stronger acid, HA or BH+? c Consider the following reaction: B(aq)+HA(aq)BH+(aq)+A(aq) Based on the information about the acid/base strengths for the species in this reaction, is this reaction favored to proceed more to the right or more to the left? Why? d An aqueous solution is made in which the concentration of weak base B is one half the concentration of its acidic salt, BHCl, where BH+ is the conjugate weak add of B. Calculate the pH of the solution. e An aqueous solution is made in which the concentration of weak acid HA twice the concentration of the sodium salt of the weak acid, NaA. Calculate the pH of the solution. f Assume the conjugate pairs B/BH+ and HA/A are capable of being used as color-based end point indicators in acidbase titrations, where B is the base form indicator and BH is the acid form indicator, and HA is the acid form indicator and A is the base form indicator. Select the indicator pair that would be best to use in each of the following titrations: (1) Titration of a strong acid with a strong base. (i) B/BH+ (ii) HA/A (2) Titration of a weak base with a strong acid. (i) B/BH+ (ii) HA/A
An aqueous solution contains a mixture of 0.0500 M HCOOH (Ka = 1.77 104) and 0.150 M CH3CH2COOH (Ka = 1.34 105). Calculate the pH of this solution. Because both acids are of comparable strength, the H+ contribution from both acids must be considered.
The simplest amino acid is glycine, H2NCH2CO2H. The common feature of amino acids is that they contain the functional groups: an amine group, -NH2, and a carboxylic acid group, -CO2H. An amino acid can function as either an acid or a base. For glycine, the acid strength of the carboxyl group is about the same as that of acetic acid. CH3CO2H, and the base strength of the amino group is slightly greater than that of ammonia, NH3. (a) Write the Lewis structures of the ions that form when glycine is dissolved in 1 M HCl and in 1 M KOH. (b) Write the Lewis structure of glycine when this amino acid is dissolved in water. (Hint: Consider the relative base strengths of the -NH2 and -CO2- groups.)
Amino acids are an important group of compounds. At low pH, both the carboxylic acid group (CO2H) and the amine group (NHR) are protonated. However, as the pH of the solution increases (say, by adding base), the carboxylic acid proton is removed, usually at a pH between 2 and 3. In a middle range of pHs, therefore, the amine group is protonated, but the carboxylic acid group has lost the proton. (This is called a zwitterion.) At more basic pH values, the amine proton is dissociated. What is the pH of a 0.20 M solution of alanine hydrochloride, [NH3CHCH3CO2H]Cl?
Nitrous acid, HNO2 (aq) has a Ka value of 4.0 x 10-4. What is the pH and POH of a 0.0500 M solution of lithium nitrite? (Assumptions may not be valid.)
The pH of human blood is steady at a value of approximately 7.4 owing to the following equilibrium reactions: Acids formed during normal cellular respiration react with the HCO3- to form carbonic acid, which is in equilibrium with CO2(aq) and H2O(l). During vigorous exercise, a person’s H2CO3 blood levels were 26.3 mM, whereas his CO2 levels were 1.63 mM. On resting, the H2CO3 levels declined to 24.9 mM. What was the CO2 blood level at rest?
Calculate the pH of a 0.75 mol L─3 solution of ethanoic acid at 298 K.Given Ka = 1.7 × 10─5
Rainwater is acidic because CO2(g) dissolves in the water, creating carbonic acid, H2CO3. If the rainwater is too acidic, it will react with limestone and seashells (which are principally made of calcium carbonate, CaCO3). Calculate the concentrations of carbonic acid, bicarbonate ion (HCO3-) and carbonate ion (CO32-) that are in a raindrop that has a pH of 5.60, assuming that the sum of all three species in the raindrop is 1.0 * 10-5 M.
Calculate the pH of the following acid solutions at 25 °C: (a) 1.0 x 10-4 M H3BO3(aq) (boric acid acts as a monoprotic acid), (b) 0.015 M H3PO4 (aq), (c) 0.10 M H2SO3(aq). Values for the successive acidity constants for each of these acids are given in the below table.
8. (a) HA(aq) is a weak acid with a dissociation constant, Ka, of 8.8 x 10−12. What is the pH of a 0.022 M solution of A−(aq)? The temperature is 25 ◦C. (b) For the reaction A(g) =A(l), the equilibrium constant is 0.666 at 25.0 ◦C and 0.222 at 75.0 ◦C. Making the approximation that the entropy and enthalpy changes of this reaction do not change with temperature, at what temperature will the equilibrium constant be equal to 0.777?
Calculate the pH and pOH of a solution resulting from dissolving 0.75 grams of perchloric acid in enough water to obtain a final solution of 1500 mL. Take into account that for each mole of perchloric acid it dissociates in the aqueous medium, releasing 1 mole of hydrogen ions.