ACIDS AND BASES

Turn to Page 43 in your

Standards Book

Standard 5 – Acids, Bases and Salts are

three classes of compounds that form ions

in water solutions

Standard 5a – Students know the

observable properties of acids, bases and

salt solutions

Acids

Produce H+ ions in water

PROPERTIES:

Taste sour

Are electrolytes (when dissolved in water can

conduct electric current)

React with metals to form H2 gas

React with bases to form salts and water

Bases

Produce OH- ions in water

PROPERTIES:

Taste bitter

Are electrolytes

Feel soapy, slippery

React with acids to form salts and water

Identification Check

Identify each as characteristic of an

A) acid or/and

B) base

____ 1. Sour taste

____ 2. Produces OH- in aqueous solutions

____ 3. Bitter taste

____ 4. Is an electrolyte

____ 5. Produces H+ in aqueous solutions

ANSWERS

Identify each as a characteristic of an

A) acid or

B) base

_A_ 1. Sour taste

_B_ 2. Produces OH- in aqueous solutions

_B_ 3. Bitter taste

A, B 4. Is an electrolyte

_A_ 5. Produces H+ in aqueous solutions

Hydrogen ions

Hydrogen ions in an aqueous solution

have several names

Proton: H+

Hydrogen ion: H+

Hydronium : H3O+

Turn to Page 45 in your

Standards Book

Standard 5c – Students know strong acids

and bases fully dissociate and weak acids

and bases partially dissociate

DISSOCIATION

Dissociation: When ionic compounds

dissolve to produce ions

Dissociation of ionic compounds occurs

when water molecules “pull apart” the ionic

crystal.

Examples of Dissociation

NaCl(s) → Na+(aq) + Cl-(aq)

Na2SO4 (s) → 2 Na+(aq) + 1 SO42-

(aq)

Acid: HClO4(s) → H+(aq) + ClO4

-(aq)

Base: Mg(OH)2 (s) → Mg2+(aq) + 2 OH– (aq

11

Strengths of Acids and Bases

Strong acids and bases completely ionize or

dissociate (100%) in aqueous solutions

Acid: HCl + H2O H+ (or H3O+) + Cl-

Base: NaOH Na+ (aq) + OH-(aq)

Strong Acid Dissociation

(makes 100 % ions)

12

Weak Acid Dissociation

(only partially ionizes)

13

14

Strong and Weak

Acids and Bases

Common Strong acids

HCl, HNO3 , H2SO4

Most other acids are weak (Acetic

Acid - HC2H3O2; examples of a weak

acid, H3PO4, HCN, HF, H2CO3)

Strong bases - NaOH, KOH, & Ca(OH)2

Most other bases are weak i.e. NH3.

H+ A - H+ A - HA

A - H+ A - H+ A –

H+ A - H+ A - H+

A - HA H+ A -

H+ A - H+ A - H+

HA HA HA HA

HA HA HA

H+ A - HA HA

HA HA H + A –

HA H + A – HA HA

H+ A- H+ A- H+ A- H+ A- HA

A- H+ A- H+ A- H+ A- H+ A -

H+ A- HA H+ A- H+ A- H+ A-

A- H+ A- H+ A- H+ A- H+ A- H+

H+ A - H + A - H + A - HA H + A -

A- H+ A- H+ A- H+ A- H+ A–

H+ A- H+ A- H+ A- H+ A- H+

A- H+ A- H+ A- H+ A- H+ A-

HA A- H+ A- H+ A- H+ A- H+

HA HA H+ A- HA HA HA

HA HA HA HA HA H+ A-

H+ A- HA HA HA HA HA

HA HA H+ A- HA HA HA

HA HA HA H+ A

- HA HA

H+ A- HA HA HA HA HA

HA HA HA H+ A

- HA HA

H+ A- HA HA HA HA HA

HA HA H+ A- HA HA HA

DILUTE CONCENTRATED

ST

RO

NG

W

EA

K

STRONG ACIDS

Dissociate nearly 100%

HA H1+ + A-

WEAK ACIDS

Dissociate very little

HA H1+ + A-

Acids: Concentration vs. Strength

Monday April 2 Notes

ended here

Strength vs. Concentration The words concentrated and dilute

refers to the number of moles of acid

or base in a given volume

The words strong and weak refer to the

extent of ionization of an acid or base

Is a concentrated, weak acid possible?

17

NEUTRALIZATION

Neutralization reaction: Acid reacts with

base to give salt (Generic term not just

NaCl) and water.

Example: HCl + LiOH → LiCl + H2O

Some Common Acids

hydrochloric acid ( HCl)

nitric acid

phosphoric acid

sulfuric acid

acetic acid (vinegar)

Ascorbic acid (Vitamin C) – citrus fruits

Some Common Bases

NaOH sodium hydroxide

KOH potassium hydroxide

Ba(OH)2 _____________________

Mg(OH)2 _____________________

Al(OH)3 aluminum hydroxide

SVANTE ARRHENIUS

Acid Acids produce H+ in water

water HCl H+ + Cl-

Base Bases produce OH- in water

water

NaOH Na+ + OH-

Acid Acids produce H+ in water

water HCl H+ + Cl-

Base Bases produce OH- in water

water

NaOH Na+ + OH-

J.N BRONSTED/T.M LOWRY

Acids are hydrogen ion (H+) donors

Bases are hydrogen ion (H+) acceptors

Pure Water is Neutral

Pure water contains small, but equal

amounts of ions: H+ and OH-

H+ OH-

Acids

Acids contain more H+

H+ OH-

Bases

Bases contain more OH-

H+ OH-

pH Range

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Neutral

H+ > OH- H+ = OH- OH- > H+

Acidic Basic

pH

Is the measure of the acidity or basicity of the

solution ( how acidic or basic a solution is)

pH means “hydrogen power” or power of

hydrogen

pH of Some Common Acids

gastric juice 1.0

lemon juice 2.3

vinegar 2.8

orange juice 3.5

coffee 5.0

milk 6.6

pH of Some Common Bases

blood 7.4

tears 7.4

seawater 8.4

milk of magnesia 10.6

household ammonia 11.0

Learning Check pH7

Identify each solution as

1. acidic 2. basic 3. neutral

A. _____ HCl with a pH = 1.5

B. _____ household cleaner pH = 12.0

C. _____ Sprite soft drink pH = 3.0

D. _____ water pH = 7.0

E. _____ orange juice pH = 3.3

F. _____ Pancreatic fluid pH = 7.7

Solution pH7

Identify each solution as

1. acidic 2. basic 3. neutral

A. _1__ HCl with a pH = 1.5

B. _2__ household cleaner pH = 12.0

C. _1__ Sprite soft drink pH = 3.0

D. _3__ water pH = 7.0

E. _1__ orange juice pH = 3.3

F. _2__ Pancreatic fluid pH = 7.7