ACIDS, BASES, AND PH OH MY!!

An introduction to the properties of acids, bases, and the pH scale

COMPLETE THE FOLLOWING TABLE

Element Atomic #

Mass # Protons Electrons

Neutrons

Ion, Isotope,

or Neutral?

82 209

16 18

Uranium 238 92

MONDAY, SEPTEMBER 17TH

Pick up the two pieces of paper from the front table.

ACIDS

Taste sour Very reactive Contain H+ (hydrogen ions) Examples:

Hydrochloric Acid (HCl) Sulfuric Acid (H2SO4) Citric Acid (citrus fruits) Acetic Acid (vinegar)

BASES

Taste Bitter Feel slippery (soap) Contain OH- (hydroxide ions) Examples:

Soap Sodium Hydroxide (NaOH) Ammonia

ACIDS VS. BASES

If the number of H+ ions in a solution is greater than number of OH- ions, the solution is an acid

If the OH- ions are greater than the H+ ions, the solution is a base

pH SCALE

Indicates hydrogen ion (H+) concentration

Ranges from 0-14 Acids are found in the 0-6 range Bases are found in the 8-14 range 7 is NEUTRAL!!

1 2 3 4 5 6 7 8 9 10 11 12 13 14 strongest acid neutral strongest base

MONDAY, SEPTEMBER 17TH

Do Now: Get out your pH notes from Friday.

Testing Day

Tomorrow!!!

pH SCALE

H+ concentration increasesOH- concentration increases

pH SCALEAs you move from pH 0 to pH 14, the concentration of H+ DECREASES (10 times each number)

As you move from pH 0 to pH 14, the concentration of OH- INCREASES (10 times each number)

PRACTICE

1. As you move from pH 7 to pH 4 what happens to H+ concentration?

2. As you move from pH 2 to pH 8 what happens to OH- concentration?

3. How much more acidic is a solution with a pH 1 vs. pH 5?

TESTING pH

pH paper OR litmus paper

BUFFERS

Neutralize acids and bases Keep the pH from undergoing large

changes

PRACTICE AND LAB

Practice: Read the entire article. Write the main point for each paragraph under the paragraph.

Lab: Make a prediction for each substance. Move around to each station and dip

the pH paper into the solution. Use the scale to determine the pH of

each substance.

LAB Liquid Prediction Actual

pH 1. White milk ________ ________ 2. V-8 Juice ________ ________ 3. Comet cleaner ________ ________ 4. Vinegar ________ ________ 5. Baking Soda ________ ________ 6. Water ________ ________ 7. Egg ________ ________ 8. Lime Juice ________ ________

POST LAB QUESTIONS

1. Which solution was the strongest acid? The strongest base?

2. Which solution was the weakest acid? The weakest base?

3. Did you predict that any solution would be neutral? Was your prediction correct? Explain.

4. How many of your predictions were confirmed during the lab? Explain.