pH

What is pH?

• pH measures the amount of H+’s in a solution– Water splits to form

ions– H+ and OH-

H+

H+

H+

H+

H+

H+

Acid

• <7 on pH scale• Higher concentration

of H+ in solution than OH-

• Properties– Sour taste– Ability to turn litmus

paper from blue to red– Proton donor

More acidic Less acidic

Basic/Alkaline

• >7 on pH scale

• More OH-, Less H+

• Properties– Slippery– Bitter– Proton recipient

Alkaline Less Alkaline

Neutral

• pH of 7

• Water!

• Balance of H+ and OH- ions

Interpreting the pH Scale

• Each decrease in number (more acidic) represents a 10x increase in the number of H+ ions

Testing pH

• Indicator: Chemical that changes color– Test to determine pH

• Litmus Test– Positive Acid Test: Turn blue litmus paper to

red– Positive Alkaline Test: Turn red litmus paper to

blue

• pH Paper– Changes color– Match color to key to determine the pH