1. Classifying
Compounds

2. Ionic Compounds: Acids, Bases & Salts
Ionic compounds are classified into 3 categories:
Acids
Bases
Salts
Note: some covalent compounds can be acids or bases as well

3. Formulas usually start with “H”
Acids
Any compound that:
Turns blue litmus paper red
Tastes sour
Reacts with some metals to produce H2 gas
Conducts electricity when dissolved in water
Produce H+ ions when dissolved in water
e.g.
HCl
hydrochloric acid (stomach acid)
H2SO4
sulphuric acid (battery acid)
H3C6H5O7
citric acid (lemons, oranges, etc.)
HCH3COO
acetic acid (vinegar)
Also can be written as CH3COOH or HC2H3O2
Formulas usually start with “H”

4. Formulas usually end with “OH”
Bases
Any compound that:
Turns red litmus paper blue
Has a bitter taste
Feels slippery
Conducts electricity when dissolved in water
Produce OH- ions when dissolved in water
e.g.
NaOH
sodium hydroxide (drain cleaner)
KOH
Potassium hydroxide (used in batteries)
NH4OH
Ammonium hydroxide (household cleaner)
Al(OH)3
Aluminum hydroxide (antacid)
Formulas usually end with “OH”

5. Neutralization reactions
When acids react with bases they form salts (and water)
Acid Base  Water Salt
e.g.
HCl(aq) + NaOH(aq)  HOH(l) + NaCl(aq)
HCl(aq) + NaOH(aq)  HOH(l) + NaCl(aq)
This is called a NEUTRALIZATION reaction
In an neutralization reaction, the properties of the acid and base are lost as water and a salt are formed.

6. Indicators
Some dyes can help classify acids and bases, they change different colours in the presence of either acids or bases.
These dyes are called INDICATORS
ACID
BASE
e.g.
Litmus
Red
Blue
Phenolphthalein
Colourless
Pink (fuchsia)
Bromothymol blue
Yellow
Blue
(See your data booklet for a more detailed listing)

7. Salts Any ionic compound which is not an acid nor a base.
e.g.
NaCl
sodium chloride (table salt)
MgF2
magnesium fluoride
CuSO4
copper(II) sulphate
Salts are formed when:
Acids react with Bases (Neutralization)
H2SO Mg(OH)2  MgSO H2O
Acid Base Salt water
Salts are made of a positive ion (from a base) and a negative ion (from an acid)

8. Salts continued
Salts can also be formed from oxides, carbonates or metals reacting with acids.
Acids + metals
2 HCl(aq) Mg(s)  MgCl2(aq) H2(g)
Salt hydrogen gas
Acids + carbonates
H2SO4(aq) + CaCO3(s)  CaSO4(aq) + H2O(l) + CO2(g)
Salt
carbonates neutralize acids
protect lakes and ecosystems from acid rain

9. Assignment In Class: Homework: Acid / Base Worksheet
Workbook Pages 91 & 92