The pH Scale

The measure of the difference between acids, bases and salts

Why do we need to know about pH?

• The pH of a substance is a chemical property of that substance.

• pH classifies a substance as an acid, base, or neutral substance

• Many life forms can only tolerate a small range of pH to live and function properly.

• Examples: Fish tanks, ponds, garden soil

pH• pH is a measure of the amount of H+ ions in a solution

• The pH scale runs from 0 to 14. A pH of 7 is NEUTRAL, less than 7 is acidic, more than 7 is basic

Acids• Sour taste• React/Corrode metals• CHANGES blue litmus paper to red• Neutralizes bases• Releases H+ ions in water (acids start with H!)• Found in: foods, stomach, batteries, fertilizers• Examples: HCl (hydrochloric acid)

H2SO4 (sulfuric acid) HNO3 (nitric acid)

Bases• Taste bitter• Feels slippery• Can irritate your skin• CHANGES red litmus paper blue

– (remember Bases and Blue)• Neutralizes acids• Releases OH- ions in water (most end with OH)• Found in: Cleaning agents and antacids• Examples: NaOH (sodium hydroxide)

LiOH (lithium hydroxide) KOH (potassium hydroxide)

When Acids and Bases Mix

• When acids and bases combine, they NEUTRALIZE!!

• When strong acids and strong bases are reacted with one another, a salt and water are the only products (totally neutral!)

• Examples of Neutralization Reactions:– HCl + NaOH NaCl + H2O– HCl + LiOH LiCl + H2O– HCl + KOH KCl + H2O

Salts

• Formed when an acid and a base are reacted with one another (NEUTRALIZATION!)

• Made of a metal and a nonmetal• AKA – an ionic compound!• NaCl, KCl, MgCl2