9.4 Naming & Writing Acids

Chapter 9

9.4 Naming & Writing Formulas for Acids

Acid – a compound that has one or more hydrogen atoms and produces hydrogen ions (H+) in solution

The basic formula is

Three rules for naming

1. When the anion (X) does not have Oxygen in it

a. The name begins with hydro

b. The anion’s name ends in –ic

c. And the word acid is added to the end

HnX

HClHydro ClHydrochloricHydrochloric Acid

Starter S-78

Name

A. N2O3

B. SO3

C. HF

Give the Formula

A. Dihydrogen monoxide

B. Carbon Monoxide

9.4 Naming & Writing Formulas for Acids

2. When the anion (X) does have Oxygen and the polyatomic ion ends in -ite

a. Use the name of the anion, but change the ending to –ous

b. Add the word acid

H2SO3SulfurousSulfurous Acid

9.4 Naming & Writing Formulas for Acids

3. When the anion (X) does have Oxygen and the polyatomic ion ends in -ate

a. Use the name of the anion, but change the ending to –ic

b. Add the word acid

H2SO4SulfuricSulfuric Acid

Oxygen?NO YES

--ous acid

Ending of Polyatomic Ion?

-ite -ateHydro—ic acid

--ic acid

9.3 Naming & Writing Molecular Compounds

Example 1

Example 2

Example 3

Example 4

HClO3Chloric Acid

HCNHydrocyanic Acid

HNO3Nitric Acid

HClO2Chlorous Acid

9.4 Naming & Writing Formulas for Acids

To write the formulas, we go backwards through our list

Acids always have an H+ ion

Hydro means no Oxygen – so Fluoric means Fluoride

Hydrofluoric Acid

Oxygen?NO YES

--ous acid

Ending of Polyatomic Ion?

-ite -ateHydro—ic acid

--ic acid

H+ Hydrofluoric AcidH+ F-HF

9.4 Naming & Writing Formulas for Acids

To write the formulas, we go backwards through our list

Acids always have an H+ ion

ous means the ion ended in ite, so phosphite

Phosphorous Acid

Oxygen?NO YES

--ous acid

Ending of Polyatomic Ion?

-ite -ateHydro—ic acid

--ic acid

H+ Phosphorous AcidH+ PO3-3H3PO3

9.4 Naming & Writing Formulas for Acids

To write the formulas, we go backwards through our list

Acids always have an H+ ion

ic means the ion ended in ate, so phosphate

Phosphoric Acid

Oxygen?NO YES

--ous acid

Ending of Polyatomic Ion?

-ite -ateHydro—ic acid

--ic acid

H3PO4

9.3 Naming & Writing Molecular Compounds

Example 1

Example 2

Example 3

Example 4

Hydroiodic AcidHI

Acetic AcidHC2H3O2

Hypochlorous AcidHClO

Carbonic AcidH2CO3

9.5 The Laws Governing Formulas and Names

Chapter 9

9.5 The Laws Governing Formulas and Names

The Law of Definite Proportions – in any chemical compound, the masses of the elements are always in the same proportion

The ratio of this molecule is always

Or (Same Ratio)

Carbon:Hydrogen2.98:1:001:00:0.34

9.5 The Laws Governing Formulas and Names

The Law of Multiple Proportions – Whenever the same two elements form multiple compounds, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers

Huh?

For example one compound

A second compound might be

The ratio of the two masses would be

5 :10gA gA5g A2g B

10g A2g B1: 2