Concept explainers
Interpretation:
Concept Introduction:
A weak acid in water produces a hydrogen ion and conjugate base. When weak acid dissolves in water, some acid molecules transfer proton to water.
In solution of weak acid, the actual concentration of the acid molecules becomes less because partial dissociation of acid has occurred and lost protons to form hydrogen ions.
The reaction is as follows:
The reaction is as follows:
The expression for
Negative logarithm of molar concentration of hydronium ion is called
The relation between
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Chemistry: Principles and Practice
- Write the chemical equation and the expression for the equilibrium constant, and calculate Kb for the reaction of each of the following ions as a base. (a) sulfate ion (b) citrate ionarrow_forwardThe pH of a 0.10-M solution of propanoic acid, CH3CH2COOH, a weak organic acid, is measured at equilibrium and found to be 2.93 at 25 °C. Calculate the Ka of propanoic acid.arrow_forwardFor 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_forward
- Calculate the pH of a 0.24 M solution of sodium lactate. The pKa of lactic acid is 3.86.arrow_forwardIf the concentration of an acid in solution is 2.3 times larger than the concentration of its conjugate base, and the pH of the solution is 4.9, what is the pKa of the acid?arrow_forwardA 0.20 M solution of niacin has a pH of 3.6. (a) What percentage of the acid is ionized in this solution? (b) What is the Ka for niacin?arrow_forward
- Sodium nitrate (NaNO2) was often added to processed meat to enhance color and to protect against the growth of clostridium botulinum, the bacterium that causes botulism. Because of the concerens about the formation of carcinogenic compounds when the meat is cooked, most governments now limit the amount of sodium nitrate that can be added to food. Calculate the pH of a 0.050 M solution of sodium nitrite. The Ka for nitrous acid is 4.5x10^-4. NaNO2 <----->Na^+ +NO2^- NO2-+H2O <-----> HNO2 +OH^-arrow_forwardCalculate the degree of ionization of morphine, pKa 8.0, in a solution with a pH of 2.2. Predict how the degree of ionization could affect the ease of absorption of morphine in (a) the stomach and (b) the intestine when the pH of the stomach fluid is 2.0 and the pH of the intestinal fluid is 6.arrow_forwardThe pKa of a particular weak acid is 4.85. What is the pH of the weak acid solution when exactly half of the acid is neutralized?arrow_forward
- The pH of a 0.45 M solution of a weak acid, HA, is 2.13. What is the value of Ka for the weak acid?arrow_forwardThe pH of an aqueous solution of weak monoprotic acid is 3.15. What is the initial concentration of the acid if the pKa of the acid 5.74?arrow_forwardHypochlorous acid, HOCl, is a weak acid having a pKa = 7.46. (a) Show the balanced chemical equation for the hydrolysis of water by OCl- (aq). (b) Compute the value of pKb for aqueous hypochlorite ion. (c) If [OCl-] = 0.050 M, then what is the pH of this aqueous solution? (a) (b) (c)arrow_forward
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