ACIDS, BASES, AND SALTS

ACIDS

•Definition:

An acid is a substance that produces H+ ions in solution

PROPERTIES OF ACIDS

•Tastes sour•Corrosive: eats away at other materials. Causes burns and tissue damage•Able to conduct electricity

PROPERTIES OF ACIDS

•Forms H+ ions in solution•Examples include: gastric juices, vinegar, lemon juice, hydrochloric acid, aspirin, fertilizer, explosives•Litmus paper test: Turns litmus paper red

BASES

•Definition:

A base is a substance that produces OH- ions in solution

PROPERTIES OF BASES

•Tastes bitter•Slippery feel. Strong bases can burn your skin•Able to conduct electricity

PROPERTIES OF BASES

•Forms OH- ions in solution•Examples include: soap, ammonia, oven and drain cleaner, deodorant, laxatives•Litmus paper test: Turns litmus paper blue

INDICATOR

• An indicator is a compound that changes color in the presence of an acid or base• Litmus paper is a common indicator.• It turns red in the presence of an acid• It turns blue in the presence of a base

THE pH SCALE

THE pH SCALE

THE pH SCALE

QUESTION

You have probably seen commercials for antacids that describe how well these products neutralize excess stomach acid.

• Would the pH of the antacid be higher or lower than 7?

The answer is: higher than 7

NEUTRALIZATION

• Only a base can neutralize and acid• Only an acid can neutralize a base

• Definition: Neutralization is a chemical reaction between an acid and a base

NEUTRALIZATION

• During a neutralization reaction, H3O+ ions from the acid combine with OH- ions from the base to produce water.

• The reaction looks like this:

H3O+ + OH- = 2H2O

NEUTRALIZATION

• As the reactive H3O+ and OH- ions combine to form water, the acidic and basic properties of the reactants are canceled out, or neutralized

• The equation only accounts for half of the ions present in the solution, though.• What happens to the remaining ions?

They react to form a salt.

NEUTRALIZATION

• Definition:A salt is a compound formed when the

negative ions from an acid combine with the positive ions from a base.

NEUTRALIZATION

• Neutralization reactions are ionic. The equation below show what happens to all of the ions during a neutralization reaction.

HCl + NaOH = H2O + NaCl (acid) (base) (water) (salt)

NEUTRALIZATION

What do you think you will get if you combine hydrochloric acid with potassium hydroxide?

HCl + KOH = ?(acid) (base)

Answer: HCl + KOH = H2O + KCl(acid) (base) (water) (salt)

SALTS

• Many substances you come into contact with everyday are salts. • The most common is NaCl, table salt. • Most salts are composed of a metal and a

nonmetal other than oxygen. • Salts can also be composed of a metal and a

polyatomic ion. Ammonium salts contain the polyatomic ion NH4+ rather than a nonmetal.

SALTS

• Salts also form when metals react with acids. Hydrogen gas is released during such reactions:

H2SO4 + Zn = ZnSO4 + H2(acid) (metal) (salt) (hydrogen gas)

NEUTRALIZATION REACTIONSHAVE THE FOLLOWING PROPERTIES:

• Water is formed• Precipitate (salt solid) is formed• Color can change• Heat can be given off• Gas can be given off