1. Chemistry 19.1

2. Acid-Base Theories
19.1
Bracken Cave, near San Antonio, Texas, is home to twenty to forty million bats. Visitors to the cave must protect themselves from the dangerous levels of ammonia in the cave. Ammonia is a byproduct of the bats’ urine. You will learn why ammonia is considered a base.

3. Properties of Acids and Bases
19.1
Properties of Acids and Bases
Properties of Acids and Bases
What are the properties of acids and bases?

4. Properties of Acids and Bases
19.1
Properties of Acids and Bases
Acids
Acids taste sour, will change the color of an acid-base indicator, and can be strong or weak electrolytes in aqueous solution.

5. Properties of Acids and Bases
19.1
Properties of Acids and Bases
Citrus fruits contain citric acid. Tea contains tannic acid.
Many items contain acids or bases, or produce acids and bases when dissolved in water. a) Citrus fruits contain citric acid. b) Tea contains tannic acid. c) Antacids use bases to neutralize excess stomach acid. d) The base calcium hydroxide is a component of mortar.

6. Properties of Acids and Bases
19.1
Properties of Acids and Bases
Bases
Bases taste bitter, feel slippery, will change the color of an acid-base indicator, and can be strong or weak electrolytes in aqueous solution.

7. Properties of Acids and Bases
19.1
Properties of Acids and Bases
Antacids use bases to neutralize excess stomach acid. The base calcium hydroxide is a component of mortar.
Many items contain acids or bases, or produce acids and bases when dissolved in water. a) Citrus fruit contain citric acid. b) Tea contains tannic acid. c) Antacids use bases to neutralize excess stomach acid. d) The base calcium hydroxide is a component of mortar.

8. Arrhenius Acids and Bases
19.1
Arrhenius Acids and Bases
Arrhenius Acids and Bases
How did Arrhenius define an acid and a base?

9. Arrhenius Acids and Bases
19.1
Arrhenius Acids and Bases
Arrhenius said that acids are hydrogen- containing compounds that ionize to yield hydrogen ions (H+) in aqueous solution. He also said that bases are compounds that ionize to yield hydroxide ions (OH–) in aqueous solution.

10. Arrhenius Acids and Bases
19.1
Arrhenius Acids and Bases
Hydrochloric Acid
Hydrochloric acid is actually an aqueous solution of hydrogen chloride. Hydrogen chloride forms hydronium ions, making this compound an acid.

11. Arrhenius Acids and Bases
19.1
Arrhenius Acids and Bases
Arrhenius Acids
Acids that contain one ionizable hydrogen, such as nitric acid (HNO3), are called monoprotic acids.
Acids that contain two ionizable hydrogens, such as sulfuric acid (H2SO4), are called diprotic acids.
Acids that contain three ionizable hydrogens, such as phosphoric acid (H3PO4) are called triprotic acids.

12. Arrhenius Acids and Bases
19.1
Arrhenius Acids and Bases

13. Arrhenius Acids and Bases
19.1
Arrhenius Acids and Bases
Arrhenius Bases
Hydroxide ions are one of the products of the dissolution of an alkali metal in water.

14. Arrhenius Acids and Bases
19.1
Arrhenius Acids and Bases

15. Arrhenius Acids and Bases
19.1
Arrhenius Acids and Bases
Milk of magnesia is a base used as an antacid.
Milk of magnesia is a base used as an antacid. Bases are usually hazardous when taken internally, but the low solubility of milk of magnesia makes it safe to use.

16. Brønsted-Lowry Acids and Bases
19.1
Brønsted-Lowry Acids and Bases
Brønsted-Lowry Acids and Bases
What distinguishes an acid from a base in the Brønsted-Lowry theory?

17. Brønsted-Lowry Acids and Bases
19.1
Brønsted-Lowry Acids and Bases
The Brønsted-Lowry theory defines an acid as a hydrogen-ion donor, and a base as a hydrogen-ion acceptor.

18. Brønsted-Lowry Acids and Bases
19.1
Brønsted-Lowry Acids and Bases
Why Ammonia is a Base
Ammonia dissolves in water to form ammonium ions and hydroxide ions. In this reaction, the water molecule donates a hydrogen ion to the ammonia molecule. Explaining
Why is ammonia not classified as an Arrhenius base?

19. Brønsted-Lowry Acids and Bases
19.1
Brønsted-Lowry Acids and Bases
Conjugate Acids and Bases
A conjugate acid is the particle formed when a base gains a hydrogen ion.
A conjugate base is the particle that remains when an acid has donated a hydrogen ion.

20. Brønsted-Lowry Acids and Bases
19.1
Brønsted-Lowry Acids and Bases
A conjugate acid-base pair consists of two substances related by the loss or gain of a single hydrogen ion.
A substance that can act as both an acid and a base is said to be amphoteric.

21. Brønsted-Lowry Acids and Bases
19.1
Brønsted-Lowry Acids and Bases

22. Brønsted-Lowry Acids and Bases
19.1
Brønsted-Lowry Acids and Bases
A water molecule that gains a hydrogen ion becomes a positively charged hydronium ion (H3O+).
When sulfuric acid dissolves in water, it forms hydronium ions and hydrogen sulfate ions. Identify which ion is the conjugate acid and which he the conjugate base?

23. Lewis Acids and Bases How did Lewis define an acid and a base? 19.1

24. 19.1
Lewis Acids and Bases
Lewis proposed that an acid accepts a pair of electrons during a reaction, while a base donates a pair of electrons.

25. 19.1
Lewis Acids and Bases
A Lewis acid is a substance that can accept a pair of electrons to form a covalent bond.
A Lewis base is a substance that can donate a pair of electrons to form a covalent bond.

26. Compare the three important definitions of acids and bases.
Lewis Acids and Bases
Animation 25
Compare the three important definitions of acids and bases.

27. 19.1
Lewis Acids and Bases

31. for Conceptual Problem 19.1
Problem Solving 19.1
Solve Problem 1 with the help of an interactive guided tutorial.

32. 19.1 Section Quiz.
19.1.

33. 19.1 Section Quiz.
1. Which of the following is NOT a characteristic of acids?
taste sour
are electrolytes
feel slippery
affect the color of indicators

34. 19.1 Section Quiz.
2. Which compound is most likely to act as an Arrhenius acid?
H2O
NH3.
NaOH.
H2SO4.

35. 19.1 Section Quiz.
3. A Lewis acid is any substance that can accept
a hydronium ion.
a proton.
hydrogen.
a pair of electrons.

36. END OF SHOW