Question from Chemistry pre-lab: Using Ka values, choose an acid/conjugate base system (monoprotic acid only) that would yield a strong buffer capacity at pH of 4.8. Explain your selection.

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Keith LeannonLv2

17 Dec 2019

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Related questions

1. Which of the following acids (listed with pKa values) andtheir conjugate base would form a buffer with a pH of 8.10?

A.	HC₇H₅O₂, pKa = 4.19
B.	HF, pKa = 3.46
C.	HClO, pKa = 7.54
D.	HClO₂, pKa = 1.96

2. When titrating a strong monoprotic acid and KOH at 25

Acid	Ka	Conjugate base	Kb
H₂CO₃	4.2 x 10^-7	HCO₃^-	2.4 x 10^-8
HCO_3^-	4.8 x 10^-11	CO₃^2-	2.1 x 10^-4

You are to prepare a carbonate buffer with a pH of 10.35. You are given carbonic acid, sodium hydrogen carbonate, and sodium carbonate.

a. Using the information in the chart about Ka/Kb values, which species will you use?

b. Which component will be present in the larger amount?

c. You are given a 0.025 M solution of the acid and a 0.025 M solution of the conjugate base. Calculate how many mL of each you would use to make the buffer.

peachelk346

For conjugate acid-base pairs, how are K_a and K_b related?

Consider the reaction of acetic acid in water.

where

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 K_a for a monoprotic strong acid is 1x10⁶, calculate K_b 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 acid 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.)