introduction to acid and base theories

1. ACIDS AND BASES
By Sthandiwe Nkwanyana

2. Discussion:
What are some
characteristics of
acids and bases do
you remember
from grade 9?

3. ACIDS
• Taste sour
• Feel rough on your fingers
• React with a base to form a salt
and water (Neutralisation
Reaction)
• Turns blue Litmus paper red
• Have a pH less than 7
BASES
• Taste bitter
• Feel slippery on your hands
• React with a base to form a salt
and water (Neutralisation
Reaction)
• Turns red litmus paper blue
• Have a pH greater than 7

4. Classify the following into acids and bases
Lemon Juice Black coffee
Bleach Urine
Soap
Vinegar
Tomato juice Bicarbonate of soda(baking soda)
Orange juice
Milk of Magnesia Gastric juice

5. Different acids and bases
Acids
• Hydrochloric acid HCL
• Hydrbromic acid HBr
• Hydriodic acid HI
• Perchloric acid HClO4
• Chloric acid HClO3
• Nitric acid HNO3
• Sulphuric Acid H2SO4
• Phosphoric Acid H3PO4
• Acetic acid CH3HOOH
• Sulfurous acid H2SO3
Bases
• Sodium hydroxide NAOH
• Potassium hydroxide KOH
• Ammonia NH3
• Sodium bicarbonate NaHCO3
• Calcium hydroxide Ca(OH)2
• Sodium carbonate Na2CO3
• Magnesium Hydroxide Mg(OH)2

6. Arrhenius Theory
• Arrhenius acid: Is a substance that reacts with water to produce
hydronium ions (H3O+)
HA + H2O  H3O+ + A- {Standard formula consider A as X}
Arrhenius base: IS a substance that reacts with water to produce
hydroxide Ions in water.
B + H2O  OH- + BH+ {Standard formula consider B as X}

7. Complete the following reactions:
HCL(aq) + H2O(l) 
NH3(aq) + H2O(i) 

8. Bronsted-Lowry Theory
• Bronsted-Lowry acid: Is a substance that donates
(gives away) protons. It is a proton donor.
• Bronsted-Lowry base: Is a substance that receives
(takes away) protons. It is a proton acceptor.

9. Examples
1. HCl(aq) + NH3(aq) 
2. CH3COOH(aq) + H2O(aq) 
3. NH3(aq) + H2O(l) 

10. In the previous questions, where did water act as
a Bronsted-Lowry acid and a Bronsted_Lowry
base?

11. Depending on what water is reacting with it can either react as a base
or as an acid.
Water is said to be amphoteric.
Amphoteric: An amphoteric substance is one that can react as
either an acid or base

12. Classwork
Identify the Bronsted-Lowry acid and base in the following:
1. HNO3(aq) + NH3(aq) 
2. HBr(aq) + KOH
3. NH3(aq) + H2O
Using water (H2O) as a reactant:
a) Write a reaction equation to show HCO−
3 acting as an acid.
b) Write a reaction equation to show HCO−
3 acting as a base.