IB Chemistry Topic R3.1.10 Acid and Base Strength and Constants Revision Notes (HL)

IB Chemistry Topic R3.1.10 Acid and Base Strength and Constants Revision Notes (HL) | RevisionDojo

Written by official IB examiners

Acid Ionization Constant ($K_a$)

When a weak acid dissolves in water, it establishes an equilibrium between the undissociated acid and its ions: $$
HA(aq) \rightleftharpoons H^+(aq) + A^-(aq)
$$
The equilibrium constant for this reaction is called the acid ionization constant ($K_a$): $$
K_a = \frac{[H^+][A^-]}{[HA]}
$$
1. [H⁺]: Concentration of hydrogen ions (or hydronium ions, $H_3O^+$).
2. [A⁻]: Concentration of the conjugate base.
3. [HA]: Concentration of the undissociated acid.

Hint

A larger $K_a$ indicates a stronger acid because more $HA$ dissociates, producing more $H^+$ ions.
Conversely, a smaller $K_a$ indicates a weaker acid.

Example

Acetic acid ($CH_3COOH$) has a $K_a$ of $1.8 \times 10^{-5}$.
This small value shows that acetic acid is a weak acid, as only a small fraction of its molecules dissociate in water.
This is why vinegar, which contains acetic acid, has a sour but not overpowering taste.

Base Ionization Constant ($K_b$)

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.

Unlock the rest of this chapter with a free account

Acid Ionization Constant ($K_a$)

When a weak acid dissolves in water, it establishes an equilibrium between the undissociated acid and its ions: $$
HA(aq) \rightleftharpoons H^+(aq) + A^-(aq)
$$
The equilibrium constant for this reaction is called the acid ionization constant ($K_a$): $$
K_a = \frac{[H^+][A^-]}{[HA]}
$$
1. [H⁺]: Concentration of hydrogen ions (or hydronium ions, $H_3O^+$).
2. [A⁻]: Concentration of the conjugate base.
3. [HA]: Concentration of the undissociated acid.

Hint

A larger $K_a$ indicates a stronger acid because more $HA$ dissociates, producing more $H^+$ ions.
Conversely, a smaller $K_a$ indicates a weaker acid.

Example

Acetic acid ($CH_3COOH$) has a $K_a$ of $1.8 \times 10^{-5}$.
This small value shows that acetic acid is a weak acid, as only a small fraction of its molecules dissociate in water.
This is why vinegar, which contains acetic acid, has a sour but not overpowering taste.

Base Ionization Constant ($K_b$)

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

Duis aute irure dolor in reprehenderit

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

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.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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 R3.1.10 Acid and Base Strength and Constants 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

Acid Ionization Constant ($K_a$)

Base Ionization Constant ($K_b$)

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

Acid Ionization Constant ($K_a$)

Base Ionization Constant ($K_b$)

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