Chapter 9
9.4 Naming & Writing Acids
9.4 Naming & Writing Formulas for Acids
Acid – a compound that has one or more hydrogen
atoms and produces hydrogen ions (H+) in
solution
Hn X
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
Hydrochloric
Hydrochloric
Hydro
HCl Cl 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
Sulfurous
Sulfurous
H2SO3Acid
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
Sulfuric
Sulfuric
H2SOAcid
4
NO
Oxygen?
Hydro—ic acid
-ite
--ous acid
YES
Ending of
Polyatomic Ion?
-ate
--ic acid
9.3 Naming & Writing Molecular Compounds
Example 1
Chloric
HClOAcid
3
Example 2
Hydrocyanic
HCN Acid
Example 3
Nitric
Acid
HNO
3
Example 4
Chlorous
HClO2Acid
9.4 Naming & Writing Formulas for Acids
To write the formulas, we go backwards through
our list
+ Hydrofluoric
+ FHHydrofluoric
HHF
Acid
Acid
Acids always have an H+ ion
Hydro means no Oxygen – so Fluoric means
Fluoride
NO
Oxygen?
Hydro—ic acid
-ite
--ous acid
YES
Ending of
Polyatomic Ion?
-ate
--ic acid
9.4 Naming & Writing Formulas for Acids
To write the formulas, we go backwards through
our list
+ Phosphorous
HPhosphorous
Acid
HH+ 3PO
PO33-3 Acid
Acids always have an H+ ion
ous means the ion ended in ite, so phosphite
NO
Oxygen?
Hydro—ic acid
-ite
--ous acid
YES
Ending of
Polyatomic Ion?
-ate
--ic acid
9.4 Naming & Writing Formulas for Acids
To write the formulas, we go backwards through
our list
H3PO4 Acid
Phosphoric
Acids always have an H+ ion
ic means the ion ended in ate, so phosphate
NO
Oxygen?
Hydro—ic acid
-ite
--ous acid
YES
Ending of
Polyatomic Ion?
-ate
--ic acid
9.3 Naming & Writing Molecular Compounds
Example 1
HI Acid
Hydroiodic
Example 2
HC2H3Acid
O2
Acetic
Example 3
Hypochlorous
HClO Acid
Example 4
Carbonic
H2CO3Acid
Chapter 9
9.5 The Laws Governing Formulas and Names
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
Carbon:Hydrogen
1:00:0.34
2.98:1:00
Or (Same Ratio)
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
5g A
2g B
5 gA
1::10
2 gA
10g A
2g B