Question

Consider the generic acid, HA, and how it interacts with water:HA (aq) + H2O (l) ⇌ H3O+ (aq) + A-Consider the following statements and answer true or false. The stronger A- is as a weak base, the stronger HA will be as a weak acid.a. True b. False Having a greater number of electron withdrawing groups is typically the best way to stabilize a conjugate base.a. True b. False If HA is a strong acid, A- will be a relatively strong weak conjugate base.a. True b. False An acid with a Ka value of 1.2 x 10-4 is a weaker acid than an acid with a Ka value of 1.5 x 10-8.a. True b. False

Answer 1

Answer:

B. False

A. True

B. False in

Explanation:

1.

From Bronsted-Lowrys definition of Acids and bases, a strong acid is a substance that gives up a proton (to form a weak conjugate base), while a strong base is one that willingly accepts a proton.

Therefore in the reaction,

HA(aq) + H2O (l) ⇌ H3O+ (aq) + A-

The stronger HA is, the weaker the A- and vice versa; the weaker HA is, the stronger A-. Example, HCl is a strong acid and its conjugate base, Cl- is a weak base.

B. False

2.

Electron drawing groups are molecules and/or atoms that enable the release of a proton from a specie. They cause inductive as well as mesomeric effects. Examples, -NO2, -COOH, -OH etc.

Fluoride ion is the most stable in this series because it's the most electronegative while carbon is the least stable because it's the least electronegative. Because of this, we were able to say that H-F was the most acidic, because it had the most stable conjugate base.

A. True.

3.

pKa1 = -log[Ka1]

= -log[1.2 x 10-4]

= 3.92

pKa2 = -log[Ka2]

= -log[1.5 x 10-8]

= 7.82

Using Bronsted-Lowry definition, the smaller the pKa value the more ease the acid loses its proton, that is, the smaller the pKa value, the stronger the acid.

Therefore, pKa2 > pKa1, so Ka value of 1.2 x 10-4 is a stronger acid than Ka value of 1.5 x 10-8

B. False.