Acids & Bases Introduction

1. What is an acid? What is a base?
What are some properties of acids? Bases?

2. • Acids are solutions with many hydrogen ions.
• A common way of representing acids is H+

3. • Acids are solutions with many hydrogen ions.
• A common way of representing acids is H+
• In reality, the hydrogen ions combine with the water in the
acid to form hydronium (H3O+). Both have 1+ charge.

4. Properties of Acids
1) Produce H+ (as H3O+) ions in water
2) Taste sour
3) Corrodes metals
4) Behaves as a good electrolyte
5) Reacts with bases to form a salt and water
6) pH is less than 7
7) Turns phenolphthalein clear
8) Turns blue litmus paper to red
• “Blue to Red A-CID”

5. Uses of Acids
• H2SO4 is sulfuric acid.
• Most widely made industrial chemical in the world.
• Used to make paper, paint, detergent and fertilizers.
• Hypochlorous acid (HClO) is used in swimming pools to kill
algae
• HCl is in your stomach to help digest food
• Citric acid and ascorbic acid are in orange juice
• Carbonic acid and phosphoric acid are in soda

6. • Lots of hydroxide ions (OH-) makes something a base.
• It has a -1 charge.

7. Properties of Bases
1) Generally produce OH- ions in water
2) Taste bitter, chalky
3) Don’t react often with metals
4) Good electrical conductor
5) Feel soapy, slippery
6) React with acids to form salts and water
7) pH greater than 7
8) Turns phenolphthalein pink
9) Turns red litmus paper to blue “Basic Blue”

8. Uses of Bases
• NaOH (sodium hydroxide) is used to make soap and
paper, oven cleaners and products to unclog drains
• Ca(OH)2 (calcium hydroxide) is used to make cement and
plaster
• Ammonia (NH3) is found in household cleaners and used
to make fertilizer
• Magnesium hydroxide Mg(OH)2 is used in antacids to
treat heartburn.

9. How can we measure if something is acidic,
neutral, or basic?

11. • The pH values of several
common substances are
shown at the right.
• Many common foods are
weak acids
• Some medicines and many
household cleaners are
bases.

12. Indicators

13. • But what does an indicator actually measure?
• Indicators measure the proportion of H3O+:OH-
• http://phet.colorado.edu/sims/html/ph-scale/latest/ph-
scale_en.html
• Click MICRO & activate
• Hint: Water is Neutral

14. • pH is a measure of the H+ concentration of a solution.
high concentration of H+ = low pH
low concentrations of H+ = high pH
[OH-] = [H+]
[OH-] < [H+]
[OH-] > [H+]

15. Note!
pH is a logarithmic scale!
• Each whole number increase in magnitude represents a
10-fold increase in acidity or basicity.
pH 4 is 10x more acidic than pH 5.
pH 3 is 100x more acidic than pH 5.
pH 3 is 10x more basic than pH 2
pH 8 is 10,000x more basic than pH 4

16. ACID OR A BASE?

17. NaOH

18. HCl

19. Cu(OH)2

20. NH3

21. H2SO4

22. HCN

23. ACTIVITY
Reactivity of Acids & Bases

24. • Record your observations. Challenge yourself to figure
out what is made.
• EXPERIMENT 1: Put a piece of magnesium into a test
tube ¼ filled with hydrochloric acid.
• EXPERIMENT 2: Put a piece of magnesium into a test
tube ¼ filled with sodium hydroxide.
•
• EXPERIMENT 3: Put a piece of calcium carbonate into a
test tube ¼ filled with hydrochloric acid.
• EXPERIMENT 4: Put a piece of calcium carbonate into a
test tube ¼ filled with sodium hydroxide.

25. Coke Cans v.s. Acids & Bases

26. Ocean Acidification

27. LAB
Properties of Acids & Bases