IB Chemistry Topic R3.1.11 Conjugate Acid-base Pair Revision Notes (HL)

IB Chemistry Topic R3.1.11 Conjugate Acid-base Pair Revision Notes (HL) | RevisionDojo

Written by official IB examiners

Conjugate Acid-Base Pair: The Relationship Between $ K_a $, $ K_b $, and $ K_w $

Note

In this article, we will recap acid and base ionization constants that were covered in the previous article, as well as explore their relation to $K_w$.

Acid Ionization Constant ($ K_a $)

When a weak acid $ HA $ dissociates in water, the equilibrium can be expressed as: $$HA(aq) \rightleftharpoons H^+(aq) + A^-(aq)$$
The equilibrium constant for this reaction, $ K_a $, is defined as: $$K_a = \frac{[H^+][A^-]}{[HA]}$$

Tip

For strong acids, $ K_a $ is very large because the acid dissociates almost completely.
For weak acids, $ K_a $ is small, indicating partial dissociation.

Base Ionization Constant ($ K_b $)

The conjugate base $ A^- $ of the weak acid $ HA $ can react with water to form $ OH^- $ ions: $$A^-(aq) + H_2O(l) \leftrightharpoons OH^-(aq) + HA(aq)$$
The equilibrium constant for this reaction, $ K_b $, is defined as: $$K_b = \frac{[OH^-][HA]}{[A^-]}$$

Note

The stronger the conjugate base, the larger the $ K_b $.
Conversely, weak conjugate bases have smaller $ K_b $ values.

The Ionic Product of Water ($ K_w $)

Water itself undergoes a small degree of ionization: $$H_2O(l) \leftrightharpoons H^+(aq) + OH^-(aq)$$
The equilibrium constant for this reaction, known as the ionic product of water, is $$K_w = [H^+][OH^-]$$ At 298 K, $K_w = 1.0 \times 10^{-14}$.

Nice try, unfortunately this paywall isn't as easy to bypass as you think. Want to help devleop the site? Join the team at https://revisiondojo.com/join-us. exercitation voluptate cillum ullamco excepteur sint officia do tempor Lorem irure minim Lorem elit id voluptate reprehenderit voluptate laboris in nostrud qui non Lorem nostrud laborum culpa sit occaecat reprehenderit

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Duis aute irure dolor in reprehenderit

Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit.

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

IB Chemistry R3.1.11 Conjugate Acid-base Pair Notes

Conjugate Acid-Base Pair: The Relationship Between $ K_a $, $ K_b $, and $ K_w $

Acid Ionization Constant ($ K_a $)

Base Ionization Constant ($ K_b $)

The Ionic Product of Water ($ K_w $)

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Conjugate Acid-Base Pair: The Relationship Between $ K_a $, $ K_b $, and $ K_w $

Acid Ionization Constant ($ K_a $)

Base Ionization Constant ($ K_b $)

The Ionic Product of Water ($ K_w $)

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Structure 1. Models of the particulate nature of matter5 subtopics

Structure 2. Models of bonding and structure4 subtopics

Structure 3. Classification of matter2 subtopics

Reactivity 1. What drives chemical reactions?4 subtopics

Reactivity 2. How much, how fast and how far?3 subtopics

Reactivity 3. What are the mechanisms of chemical change?4 subtopics

IB Chemistry R3.1.11 Conjugate Acid-base Pair Notes

Structure 1. Models of the particulate nature of matter5 subtopics

Structure 2. Models of bonding and structure4 subtopics

Structure 3. Classification of matter2 subtopics

Reactivity 1. What drives chemical reactions?4 subtopics

Reactivity 2. How much, how fast and how far?3 subtopics

Reactivity 3. What are the mechanisms of chemical change?4 subtopics

Conjugate Acid-Base Pair: The Relationship Between $ K_a $, $ K_b $, and $ K_w $

Acid Ionization Constant ($ K_a $)

Base Ionization Constant ($ K_b $)

The Ionic Product of Water ($ K_w $)

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Conjugate Acid-Base Pair: The Relationship Between $ K_a $, $ K_b $, and $ K_w $

Acid Ionization Constant ($ K_a $)

Base Ionization Constant ($ K_b $)

The Ionic Product of Water ($ K_w $)

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account