Section 2.4—Defining, Naming & Writing Acids & Bases

We need to know how acids and bases behave when talking about ant-acids!

Acids

Acids – Arrhenius DefinitionA compound that has a H+ cation that it

can donate to water to produce the hydronium ion (H3O+1)

H

OH

water

H+1

H

OH

H +1

By this definition, if an acid is to give a H+1 to water, then all acids will have hydrogen as the cation (first element written).

hydronium ion

How do Acids produce Hydronium?

H

OH

H -

water acid

Hydrogen cation with some anion

How do Acids produce Hydronium?

H

OH

H -+1

How do Acids produce Hydronium?

H

OH

H+1 -

Hydronium ion Anion

Naming Acids

These compounds :Start with “H” (more than 1 “H” is OK, too).Have only 2 elements in total (One of them is

hydrogen the other is NOT oxygen.)Examples: HCl H2S

To name these compounds:Use “hydro____ic acid”Fill in the blank with the anion’s name without

the last syllable

Naming Non-oxygen Acids

Example #1

HBr

Example #1

HBr

Hydrogen cation

Bromine

It’s an acid

No oxygenUse “hydro___ic”

Hydrobromic acid

These compounds have:Start with “H” (more than 1 “H” is OK, too).Contain a polyatomic ion that has oxygen in it.

To name these compounds:Use “___ic acid” for “-ate” anions; the blank is

filled in with the polyatomic ions name without the suffix.

Use “___ous acid” for “-ite” anions; the blank is filled in with the polyatomic ions name without the suffix.

Naming Oxygen Acids

Examples: HNO2 is . . . HNO3 is . . .

Example #2

H2SO3

Example #2

Hydrogen cation

Sulfite ion

It’s an acid

“-ite” ionUse “___ous” acid

H2SO3

Sulfurous acid

Example #3

H2SO4

Example #3

Hydrogen cation

Sulfate ion

It’s an acid

“-ate” ionUse “___ic”

H2SO4

Sulfuric acid

Let’s Practice

Example:Write the name for the following

compounds

HI

H2CO3

HC2H3O2

H3PO3

Let’s Practice

hydroiodic acid

carbonic acid

acetic acid

phosphorous acid

Example:Write the name for the following

compounds

HI

H2CO3

HC2H3O2

H3PO3

Writing Acid Formulas

To write these formulas:The cation is H+1

Write the anion and chargeBalance the charges by adding the appropriate

subscript to the hydrogen cation

“Hydro-” acids

Example #4

Hydrofluoric acid

Example #4

Hydrofluoric acid

Hydrogen cation

Only one other element

H+1

F-1

Example #4

Hydrofluoric acid

Hydrogen cation

Does not contain oxygen

H+1

F-1

HFH+1F-1

To write these formulas:The cation is H+1

If it is an “-ic” acid, the anion is the “-ate” polyatomic ion

If it is an “-ous” acid, the anion is the “-ite” polyatomic ion

Add subscript to the hydrogen cation to balance charges

NON “Hydro-” acids

Example #5

Carbonic acid

Example #5

Carbonic acid

Hydrogen cation

From the “___ate” anion

H+1

CO3-2

Example #5

Carbonic acid

Hydrogen cation

From the “___ate” anion

H+1

CO3-2

H2CO3

H+CO32-

Example #6

Nitrous acid

Example #6

Nitrous acid

Hydrogen cation

From the “___ite” anion

H+1

NO2-1

Example #6

Nitrous acid

Hydrogen cation

From the “___ite” anion

H+1

NO2-1 HNO2

H+NO2-

Let’s Practice

Example:Write the

formula for the following acids

Phosphoric acid

Hydroiodic acid

Acetic acid

Perchloric acid

Phosphoric acid

Hydroiodic acid

Acetic acid

Perchloric acid

Let’s Practice

H3PO4

HI

HC2H3O2

HClO4

Example:Write the

formula for the following acids

Bases

Objective:•Define and distinguish between acids & bases•Explain and use nomenclature rules for naming and writing formulas for bases

Bases – Arrhenius Definition

Bases produce the hydroxide ion in water

MOST bases will be ionic compounds with the OH-1 anion. (Ex. NaOH or Ca(OH)2)

MOST IMPORTANT EXCEPTION is NH3 (ammonia).NH3 + H2O NH4

+1 + OH-1

HO-1

Hydroxide Ion

Naming & Writing Bases

Most bases are just ionic compounds with “hydroxide” as their anion

The most common exception to this is ammonia. NH3 is a base even though it doesn’t contain “-OH” as the anion.

Naming Bases

Example #7

NaOH

Example #7

NaOH

Sodium

Hydroxide

Sodium Hydroxide

Example #8

Iron (III) hydroxide

Fe+3 OH-1

criss –cross the number of the charges

Fe(OH)3

Let’s Practice

Example:Write the formula or

name for each

Ca(OH)2

KOH

Sr(OH)2

Copper (II) hydroxide

Magnesium hydroxide

Let’s Practice

Calcium hydroxide

Potassium hydroxide

Strontium hydroxide

Cu(OH)2

Mg(OH)2

Example:Write the formula or

name for each

Ca(OH)2

KOH

Sr(OH)2

Copper (II) hydroxide

Magnesium hydroxide