The objective of this lab is to compare the pH of Coca-Cola from the USA to the pH of Coca-Cola from Mexico. We will also test and compare the pH of other liquids.

Materials:

CASIO Data Analyzer EA-100
CASIO CFX-9 850Ga Plus

Two 100 ml beakers

Coca-Cola (from USA) bottle soda

Coca-Cola (from Mexico) bottle soda

Orange juice

Lemon juice

milk

tap water

Procedure:

1. In one beaker, pour 50 ml of Coca-Cola (USA).
2. In second beaker, pour 50 ml of Coca-Cola (Mexico).
3. Test the pH of the soda from the USA; clean pH probe and transfer data into calculator. Repeat with 5 different soda bottles.
4. Test the pH of the soda from Mexico; clean pH probe and transfer data into calculator. Repeat with 5 different bottles.
5. Once you have collected data add water to one of the beakers and watch the pH change. Start with 1ml of water, then 2ml, 4ml, 6ml (you should end up with a total of 6ml of water in the beaker.)
6. * Test the pH of different liquids to compare the pH of solutions such as : orange juice, lemon juice, milk, tap water.

LIQUID pH OTHER LIQUID pH

Coke #1 orange juice

Coke #2 lemon juice

Coke #3 milk

Coke #4 tap water

Coke #5

Coke (Mex.) #1

Coke (Mex.) #2

Coke (Mex.) #3

Coke (Mex.) #4

Coke (Mex.) #5

What does a graph of the pH of the USA Coca-Cola and Mexico Coca-Cola look like?

What happened to the soda's pH as you added water?

Compare the pH of soda to other liquids.

Which has the most acidic pH?

Which has the most basic pH?

**Teacher's Note** You can vary the solutions you test as you see fit. You can have students observe an acidic pH change to a basic change ( or vice versa) and record the data using this equipment as well.