3. Acids and Bases

Using pKₐ values, calculate K_eq for the following acid–base reaction.

Using pKₐ values, calculate the equilibrium constants for the following acid–base reactions.

(b)

Calculate K_eq for the following acid–base reactions.

(b)

Given the pK_b, calculate the pK_a of the conjugate acid.

(c)

Calculate the equilibrium constant for each of the acid–base reactions shown.

b.

Predict the K_eq for the following acid–base reaction.

We usually calculate K_eq for acid–base reactions using pK_a values.

(a) Derive an equation to calculate K_eq using pK_b values, then

(b) use it to calculate the equilibrium constant for the following reaction.

Given the pK_b, calculate the pK_a of the conjugate acid.

(b)

Calculate K_eq for these acid–base reactions.

(d)

Using pK_a values for the conjugate acids of the bases on each side of the reaction arrow, identify which side of the equilibrium would be favored in the following hypothetical reactions.

(c)

Calculate K_eq for the acid–base reaction shown. Which side is favored and why?

Write the K_eq expression for the following acid–base reactions. [You don't need to calculate K_eq here.]

(c)

Parts (a)–(d) of this assessment assist in the development of what will become a common theme in organic reactions and should be worked in order. [Think carefully about how each question relates to the others.]

(c) Without worrying about the mechanism of the reaction, estimate an equilibrium constant for the following carbonyl addition reaction based on the relative stability of the Lewis bases.

Calculate the equilibrium constant for the reaction of ethylamine and propanoic acid. Which side is favored?

How do you know that a proton with a low pK_a value is acidic (besides 'I just remember')?