pH scale lesson

pH Scale

11 - 14 = Strong

8 - 10 = Weak

Bases

0 - 3 = Strong

4 - 6 = Weak

Acids

pH = strength of acids/bases

Scale from 0 - 14

Multiple Choice

What pH would indicate the strongest acid?

• 0

• 1

• 6

• 14

Ion Concentration

As the pH level changes, so does the concentration of ions

Hydronium (H₃O+) Ions ----- greater concentration in acids
Hydrogen (H+) Ions --------- greater concentration in acids
Hydroxide (OH-) Ions ------- greater concentration in bases

Multiple Choice

A solution has a pH of 7 - what can you tell about its ion concentration?

• More H+ Ions

• More OH- Ions

• No Ions

• Equal amount of H+ and OH- Ions

How strength changes with pH

1 number on pH scale = 10x stronger/weaker


* How much stronger is a pH of 3 than a pH of 4?


10¹ = 10x

Multiple Choice

What is the difference in strength between a lemon and coffee?

• 30x

• 3x

• 100x

• 1000x

Indicators

Substance that changes color to
show pH level.
*Liquids and Solids


Examples
Litmus Paper - Blue = Base, Red = Acid
pH Paper - Scale of 0-14
Universal Indicator Solution - 0-14