1. General Chemistry Spring 2013
ACIDS AND BASES UNIT 10
General Chemistry Spring 2013

2. The Importance Of acids… Blood is controlled by buffers
Citrus fruits (citric acid)
Vinegar (acetic acid)
Vitamin C (ascorbic acid)
Aspirin (acetyl salicylic acid)
Car batteries (sulfuric acid)

3. The Importance Of bases… Baking soda Milk of magnesia
Antacids have carbonates, bicarbonates and hydroxides to neutralize acids
Ammonia (cleaning products)
Sodium hydroxide, aka: lye (oven and drain cleaner)

4. Dangers of acids and bases

5. Resources Dangers of sodium hydroxide Chemical Burn Coke Cans
Dangers of Coke and Pepsi

6. How do you know you have…
An acid?
Produces H+ in water
Blue litmus paper turns red
Sour taste
Reacts on metal
pH less than 7
Metal etched using acid

7. How do you know you have…
A base?
Produces OH- ions in water (hydroxide ions)
Red litmus paper turns blue
Slippery feel
Bitter taste (taste shampoo tomorrow morning)
pH higher than 7

8. pH
Means “potency of hydrogen”

9. The pH Scale

10. Arrhenius Acids
Substance that ionizes in water to produce hydrogen ions (H+)
“ionization”- process by which covalent compounds form cations and anions
Ex) HCl  H Cl-

11. Arrhenius Base
Substance that dissociates in water to release hydroxide ions (OH-)
“dissociation”- process by which ionic compounds separate into ions
Ex) NaOH  Na OH-

12. Neutralization Reactions
An acid neutralizes a base to yield a salt and water.
Example A) Hydrochloric acid reacts with sodium hydroxide to give the salt sodium chloride and water.
HCl NaOH  NaCl H2O
Different acids yield different salts, but water is always a product
When you mix an acid and base, you reach an equivalence point (when the # moles of H+ = # moles of OH-)

13. Neutralization Reactions
Example B) H2SO NaOH  Na2SO H2O
The hydrogen ion (H+) from the acid is neutralized by the hydroxide (OH-) ion from the base.
These two ions combine to form water.

14. Identifying an Acid and Base
Each salt is composed of the cation (+) from the reacting base and the anion (-) from the acid.
Predict the acid and base that produce the following salts:
Potassium acetate, KC2H3O2
Let’s see some steps first.

15. Predicting Acids and Bases
Split the salt and water (HOH) formula into ions
Which ion gets H+? Write the formula
Which ion gets OH-? Write the formula
Potassium acetate, KC2H3O2
KOH + HC2H3O2  KC2H3O2 + HOH
OPPOSITES ATTRACT!

16. Predicting Acids and Bases
Lithium fluoride, LiF
HF LiOH  Li F H2O

17. The pH Scale Revisited What is pH again?
It expresses the acidity of a solution; the concentration of hydrogen ions
Ranges from…
0  14
As pH decreases, the concentration of hydrogen ions increases, and the concentration of hydroxide ions decreases.
In a neutral solution, the concentration of hydroxide ions and hydrogen ions are equal.

18. Acid-Base Indicators Methyl Red Color change ~pH 5 Below pH 5: red
Above pH 5: yellow
At 5? Orange (only a portion has been converted from yellow to red)

19. Acid-Base Indicators Bromthymol blue Color change ~pH 7
Below pH 7: yellow
Above pH 7: blue
At 7: greenish
Good test for CO2 in lungs

20. Acid-Base Indicators Phenolphthalein Color change ~ pH 9
Below pH 9: colorless
Above pH 9: pink
At pH 9: very light pink