ACIDS AND BASES

Chemistry Joke

THE BASE IS UNDER A SALT!

ACIDS AND BASES Acids and bases are two classes of

chemical compounds that we encounter frequently in everyday living.

Vinegar and lemon juice are common acids.

Ammonia and bleach are common bases.

Acids and bases have opposite properties and the ability to cancel or neutralize each other.

Almost all acids begin with H+, and most bases end with OH-.

PROPERTIES OF ACIDS Taste sour Are strong or weak

electrolytes React with bases to

form water and salts

React with active metals to produce H2

Turn litmus (and cabbage) red

Low pH

NAMING ACIDS—A REVIEWAnion Endin

gExample Acid Name Example

-ide Cl-, chlorideHydro-(stem)-

icHydrochloric acid,

HCl

-ite SO32-, sulfite (stem)-ous

Sulfurous acid, H2SO3

-ate NO3-, nitrate (stem)-ic Nitric acid, HNO3

PROPERTIES OF BASES Taste bitter Are strong or weak

electrolytes React with acids to

form water and salts Feel slippery Turn litmus (and

cabbage) blue High pH

TWO ACID/BASE THEORIES Arrhenius Bronsted-

Lowry

ARRHENIUS Simplest definition

and most restrictive

Acids supply H+ ions

Bases supply OH- ions

BRONSTED-LOWRY Added to Arrhenius

definition of bases Acids are proton

(H+) donorsBut… Bases are proton

(H+) acceptorsDon’t necessarily

have to supply OH-

NH3 (ammonia) can now be recognized as a base.

CONJUGATE ACID/BASE PAIRS Bronsted-Lowry also defined conjugate

acids and bases. HA + H2O A− + H3O+

HA is an acid. The product A- is its conjugate base.

H2O is behaving as a base. The product H3O+ is its conjugate acid.

These pairs differ by only one H+.The compound with the extra H+ is the acid.

SELF-IONIZATION OF WATER Sometimes when water molecules

collide, a hydrogen ion transfers. H20 + H20 H3O+ + OH-

Hydronium ion Hydroxide ion

Water can act as both an acid and a base, producing both H+ and OH- ions.

Sometimes the self-ionization of water is shown as: H20(l) H+(aq)+ OH-(aq)

H+ and H3O+ are often used interchangeably.

STRONG ACIDS AND BASES Strength in acids and bases does NOT

refer to how corrosive or dangerous they are.

Strong acids and bases dissociate (break apart) completely in water.

At equilibrium, there is no acid or base left that has not ionized (separated into its ions)

One of the most corrosive and dangerous acids, HF, is actually a weak acid.

STRONG VS. WEAK

http://www.mhhe.com/physsci/chemistry/chang7/esp/folder_structure/ac/m2/s1/acm2s1_1.htm

ACID / BASE NEUTRALIZATION

When an acid reacts with a base, both

are neutralized as water and a salt are

produced.

Predict the products and write the

balanced equation for the reaction of

sulfuric acid with potassium hydroxide.

Chemistry Joke

Q: Why do chemistry professors like to teach about ammonia?

A: Because it’s very basic material!