What You Need to Know About Acids and Bases

Pg. 77-78 of composition notebook

Definitions

Acid: Substance that donates Hydrogen ions (H+) to a solution. Or forms H3O+ (hydronium ions) with

water

Base: Substance that donates hydroxide ions (OH-) to a solution.

Water is Both an Acid and A Base

H2O H+ + OH-

Water hydrogen ion + hydroxide ion

pH Scale

pH is a way to measure the amount of acid in solution

Scale ranges from 0 to 14 A pH of 7 = neutral (neither acidic

nor basic) pH below 7 is acidic pH greater than 7 is basic

Properties of acids

Examples: Acetic acid (vinegar), carbonic acid (carbonated beverages), hydrochloric acid (stomach acid), lemon juice

Have a sour taste React with metals Produce color changes in indicators

Litmus paper-turns blue litmus paper red

Properties of Bases

Examples: Aluminum Hydroxide (deodorant), antacids, sodium hydroxide (soap production, drain cleaner)

Bitter taste Slippery feel (think soap) Color changes in indicators

Red litmus paper will turn blue Phenolphthalein will turn red

Opener 12/20 – pg. 77 or 78

1. What does red and blue litmus paper tell you about a substance?

2. Do you need to use both pieces of litmus paper to sample a substance? Why or why not?

3. What would it tell you about a substance if neither paper changed color?

Acid-Base Investigation –pg. 79

Question: Which foods and household substances are acids and which are bases?

Data:

Data Table A: pH of Substances

Substance pH Prediction Actual pH

1-Tap Water

2-Lemon Juice

3-Vinegar

4-Cola

5-Mouth Wash

6-Antacid

7-Coffee

8-Milk

9- Baking Soda

Data Table B: Buffer ActionSubstance Initial pH pH with 1

drop of acid

pH with 2 drops of

acid

pH with 3 drops of

acid

Tap water

Liver homogenate

Opener 1/6 – pg. 81

WITHOUT looking at your notes (or book, or discussing with another person), write down what you remember about acids and bases.

Analysis for Part A

For each substance discuss the following in complete sentences: Share the name and measured pH value

of the substance. Explain how the pH of the substance

influences its properties, uses and side effects (or lack thereof).

Analysis for Part B

Based upon your results in part B, what do you think a function of the liver is? Use your specific data to support your answer.

Why did we add the acid to water as well?