1. 9.3 Acids and Bases Obj S3 and S4
Chemistry

2. Essential Questions
What are some properties of acids? Bases? What do they share?
What is an acid? What is a base?
What are conjugate acid-base pairs?
What makes an acid/base weak? Strong?
What is an amphoteric compound?

3. Properties of Acids and Bases
Aqueous solutions of acids have a sour taste.
Acids react with metals to release hydrogen gas.
Turns litmus paper red
Bases:
Aqueous solutions of bases taste bitter.
Dilute aqueous solutions of bases feel slippery.
Turn litmus paper blue

4. Properties of Acids and Bases (cont)
Properties of both acids and bases:
Conduct electrical current in solution
React to make salt and water in neutralization reactions

5. Industrial Acids
Sulfuric acid used in the production of paints, papers, dyes, detergents and automobile batteries.
Nitric acid used to make explosives, rubber, plastics and pharmaceuticals.
Phosphoric acid used for manufacturing fertilizers and animal feed.

6. Commonly used bases Ammonia, used as a household cleaner.
Sodium hydroxide commonly called lye.
Sodium hydrogen carbonate, baking soda.
Most other cleaning products.

7. Arrhenius Acid and Base definition
Arrhenius defined an acid as a material that can release a proton (H+) in an aqueous solution
He defined a base as a substance that increased the concentration of hydroxide ions (OH-) in aqueous solutions.

8. Bronsted-Lowry Acids and Bases
Bronsted-Lowry independently defined an acid as a molecule or ion that is a proton donor.
A base is a molecule or ion that is a proton acceptor.

9. Bronsted-Lowry Acid-Base Reaction
In a Bronsted-Lowry Acid-Base reaction protons are transferred from one reactant (acid) to another (base).
H2SO4 + H2O  H3O+ + HSO4- acid base conjugate conjugate
acid base

10. Conjugate Acid-Base Pairs
Conjugate base is the compound that remains after a Bronsted-Lowry acid has given up a proton.
Conjugate acid is the compound that is formed when a Bronsted-Lowry base gains a proton.
Conjugate acid-base pair is the combination of two substances that only differ by a proton or H+.(see table 19.3 on p 591)

11. Conjugate Acid-Base Pairs (cont)
HF + H2O  F- + H3O+
The F- is the conjugate base of HF.
The H3O+ is the conjugate acid of water.
The F- and HF are conjugate pairs.
Water and the H3O+ are conjugate pairs.

12. Acid-Base conjugate pair strength
Acid-Base conjugate pair strength are inversely proportional so as one increases in strength the other decreases in strength.
The stronger the acid/base the weaker its conjugate and vice versa.
A strong acid would have a weak conjugate base

13. Strong Acids and Bases What makes something a strong acid or base?
ionizes (breaks apart into ions) completely in aqueous solutions.
What makes something a weak acid or base?
Do NOT completely ionize
P 605 lists common acids and bases

14. Amphoteric compounds H2SO4 + H2O  H3O+ + HSO4- NH3 + H2O  NH4+ + OH-
Any species that can react as either an acid or base is an amphoteric compound.
H2SO4 + H2O  H3O+ + HSO4-
water accepts a proton thus is a base.
NH3 + H2O  NH4+ + OH-
water donates a proton thus is an acid.
Water, therefore can be either an acid or a base thus is amphoteric.

15. Essential Questions
What are some properties of acids? Bases? What do they share?
What is an acid? What is a base?
What are conjugate acid-base pairs?
What makes an acid/base weak? Strong?
What is an amphoteric compound?

16. 9.3 Tracked Assignment
Worksheet