1. What is pH?

2. Water
In a sample of water, a small amount of the water ionizes into H+ and OH-
H2O → H+ + OH-
The more H+ is in a sample, the more acidic it is
The amounts of h+ and OH- ions are very small
Neutral H+ = 1 x 10-7
Acidic H+ = 1 x 10-3
Basic H+ = 1 x 10-12

3. Calculating ph
These small numbers in scientific notation are difficult to work with
Shorthand way to represent these numbers is with a log scale
pH = - log [ h+ ]
logs show the exponent of the base 10
ph = - log ( 1 x 10-4) = 4

4. The pH Scale Each pH unit is 10 times as large as the previous one
A change of 2 pH units means 100 times more basic or acidic
x10
x100

5. The pH Scale Careful measurement is important
A mistake of one pH unit means 10 times too much or too little!
x10
x100

6. To Use pH Paper Place the edge of the pH paper into the mixture.
Observe the color change of the pH paper
Match the resulting color to the colors listed on the outside of the pH paper package.
The colors match with a correlated pH number.
The number is the pH value of the sample.