Concept explainers
(a)
Interpretation:
The formula for the percent ionization of the weak acid needs to be derived using the appropriate assumptions.
Concept introduction:
The pH of the solution is used to measure the hydrogen ion’s molar concentration in the solution, and it is the measure of basicity or acidity of a solution. For any solution, if pH is less than 7 then it is acidic. pH equal to 7 is neutral and solution having pH greater than 7 is basic. The hydrogen ion’s concentration is greater than hydroxide ions in an acidic solution.
(b)
Interpretation:
The percentage ionization of formic acid solution, HCOOH (aq) needs to be determined, having pH of 2.50.
Concept introduction:
As per the Bronsted-Lowry theory of bases and acids, proton acceptors are bases and proton donors are acids. Molecules which can either accept or donate the proton are known as amphiprotic. So, an amphiprotic act as either base or acid. Hydrogen sulfate ion, hydrogen carbonate ion, amino acids and water are common illustrations of amphiprotic molecules because they might donate the proton. Moreover, all of the amphiprotic species have hydrogen atom.
(c)
Interpretation:
The value of Ka of a 0.150 M solution of propanoic acid with pH 2.85 needs to be determined.
Concept introduction:
As per the Bronsted-Lowry theory of bases and acids, proton acceptors are bases and proton donors are acids. Molecules which can either accept or donate the proton are known as amphiprotic. So, an amphiprotic act as either base or acid. Hydrogen sulfate ion, hydrogen carbonate ion, amino acids and water are common illustrations of amphiprotic molecules because they might donate the proton. Moreover, all of the amphiprotic species have hydrogen atom.
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GENERAL CHEMISTRY(LL)-W/MASTERINGCHEM.
- For conjugate acidbase pairs, how are Ka and Kb related? Consider the reaction of acetic acid in water CH3CO2H(aq)+H2O(l)CH3CO2(aq)+H3O+(aq) where Ka = 1.8 105 a. Which two bases are competing for the proton? b. Which is the stronger base? c. In light of your answer to part b. why do we classify the acetate ion (CH3CO2) as a weak base? Use an appropriate reaction to justify your answer. In general, as base strength increases, conjugate acid strength decreases. Explain why the conjugate acid of the weak base NH3 is a weak acid. To summarize, the conjugate base of a weak acid is a weak base and the conjugate acid of a weak base is a weak acid (weak gives you weak). Assuming Ka for a monoprotic strong acid is 1 106, calculate Kb for the conjugate base of this strong acid. Why do conjugate bases of strong acids have no basic properties in water? List the conjugate bases of the six common strong acids. To tie it all together, some instructors have students think of Li+, K+, Rb+, Cs+, Ca2+, Sr2+, and Ba2+ as the conjugate acids of the strong bases LiOH, KOH. RbOH, CsOH, Ca(OH)2, Sr(OH)2, and Ba(OH)2. Although not technically correct, the conjugate acid strength of these cations is similar to the conjugate base strength of the strong acids. That is, these cations have no acidic properties in water; similarly, the conjugate bases of strong acids have no basic properties (strong gives you worthless). Fill in the blanks with the correct response. The conjugate base of a weak acid is a_____base. The conjugate acid of a weak base is a_____acid. The conjugate base of a strong acid is a_____base. The conjugate acid of a strong base is a_____ acid. (Hint: Weak gives you weak and strong gives you worthless.)arrow_forwardEstimate the pH that results when the following two solutions are mixed. a) 50 mL of 0.3 M CH3COOH and 50 mL of 0.4 M KOH b) 100 mL of 0.3 M CH3COOH and 50 mL of 0.4 M NaOH c) 150 mL of 0.3 M CH3COOH and 100 mL of 0.3 M Ba(OH)2 d) 200 mL of 0.3 M CH3COOH and 100 mL of 0.3 M Ba(OH)2arrow_forwardLactic acid, C3H6O3, occurs in sour milk as a result of the metabolism of certain bacteria. Calculate the pH of a solution of 56. mg lactic acid in 250. mL water. Ka for D-lactic acid is 1.5 × 10−4.arrow_forward
- 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?arrow_forwardWhat is the pH of a solution obtained by mixing 235 mL of NaOH with a pH of 11.57 and 316 mL of Sr(OH)2 with a pH of 12.09? Assume that volumes are additive.arrow_forwardWhat is the freezing point of vinegar, which is an aqueous solution of 5.00% acetic acid, HC2H3O2, by mass (d=1.006g/cm3)?arrow_forward
- Using the diagrams shown in Problem 10-117, which of the solutions would have the greatest buffer capacity, that is, greatest protection against pH change, when the following occurs? a. A strong acid is added to the solution. b. A strong base is added to the solution.arrow_forwardBoric acid, B(OH)3, is used as a mild antiseptic. What is the pH of a 0.015 M aqueous solution of boric acid? What is the degree of ionization of boric acid in this solution? The hydronium ion arises principally from the reaction B(OH)3(aq)+2H2O(l)B(OH)4(aq)+H3O+(aq)arrow_forward
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