1. Chapter 9 Acids, Bases and Salts
9.2 Reactions of Acids with Bases

2. D12
D12 - Explain the chemical composition of acids and bases, and explain the change of pH in neutralization reactions.

3. Neutralization What is neutralization?
This is a chemical reaction between an acid and a base.
When neutralization occurs, there are two products formed …
1. salt
2. water

4. How does every single neutralization reaction form water as a product?
What is the ion formed by acids in water?
Hydrogen ion H+ or Hydronium ion H3O+
What is the ion associated with bases?
Hydroxide ion OH-
What happens when these two molecules get together?
H3O+ + OH H2O
H+ + OH H2O

5. How does every single neutralization reaction form a salt as a product?
Remember … not every salt is the “salt” that you are thinking about!
A “salt” is any ionic compound formed from a cation (positive ion) and an anion (negative ion).
While table salt (NaCl) is a “salt,” it is certainly not the only one out there!

6. ACID + BASE  SALT + WATER
The example of
Hydrochloric acid + Sodium hydroxide (base)
ACID + BASE  SALT + WATER
HCl + NaOH  NaCl + H2O =
Salt water!

7. KOH + HNO3  H2O + KNO3
Acid?
Base?
Salt?
HNO3
KOH
KNO3

8. Acid, Base, or Neutralization?
NH3 + H2O  NH4+ + OH- HClO + LiOH  LiClO + H2O HCl + H2O  H3O+ + Cl-
Base – because OH- is present in the products
Neutralization – because of the salt and water in the products
Acid – because H3O+ is present in the products

9. Do these reactions always result in neutral solutions?
No. Remember that it takes one H+ (or H30+) to cancel out one OH-.
So, unless the amount of H+ from the acid and the OH- from the base are balanced, the resulting solution will not be neutral.

10. So, how can you tell if the resulting solution will be acidic or basic?
The pH of final solution depends on the amounts and strength of the acid and base.
If there is more OH- present than H+, the resulting solution will be basic.
If there is more H+ present than OH-, the resulting solution will be acidic.

11. You try …
What would result from mixing equal amounts of a weak base and a strong acid?
An acidic solution

12. Salts
Remember, a salt is another name for an ionic compound, which is a combination of cations and anions.
Common salts:
Table salt - NaCl
Baking soda – NaHCO3
Highway de-icers – often CaCO3 and MgCl2
Fire extinguishers – NaHCO3, KHCO3 and ((NH4)H2PO4
Antiperspirants and deodorants - AlK(SO4)2

13. Salts in the Body
Minerals are inorganic elements that come from the soil and water. Your body needs minerals to grow and stay healthy. Minerals contain salts of elements that are needed by your body
Ca – strong bones and teeth, nerves and muscles
K and Na – nerve impulses, water content of cells
P – transportation of energy, DNA replication

14. We will use our knowledge of acids and bases to understand acid rain.
What’s next?
We will use our knowledge of acids and bases to understand acid rain.