ACIDS AND BASES

CHAPTER 19

Pages 594-633

Properties of Acids

• Acids have a SOUR taste

• Turn blue litmus paper RED

• Conduct electricity

• React with metals to produce H2 gas

(Single Replacement reaction)

• Form H+ ions in water

• pH < 7.0

Acids (continued)

• React with BASES to produce a salt & H2O (aka a DOUBLE REPLACEMENT

& NEUTRALIZATION REACTION)Remember: A salt is an ionic compound, a metal and non-metal. An electrolyte is a substance which conducts electric current.

ALL ACIDS MUST CONTAIN

HYDROGEN

• Acids containing only one hydrogen

are called Monoprotic, Ex: HNO3

• Acids with two hydrogens are didiproticprotic,

EX: H2SO4 & H2CO3

• Acids with 2 or more are polypolyprotic,

EX: H3PO4

ACID NOMENCLATURE

• Binary- contain 2 different elements

Hydrogen and one other element

Binary acids begin with HYDRO

Hydro + root word of 2nd element + IC

Examples of Binary Acids

• HF - Hydrofluoric

• HCl - Hydrochloric

• HBr - Hydrobromic

• HI - HydroIodic

• H2S - Hydrosulfuric

OXY acids

• Contain OXYGEN

hydrogen

one other non metal

OXY acid nomenclature

• Named after POLYATOMIC ion they contain (…ate or …ite)

RECALL:

• “If I ate an acid, it would make me sick”

• “Dynamite is dangerous”

HERE WE GO!!

• HNO3 (nitrate) HNO2 (nitrite)

Nitric Nitrous

• H2SO4 (sulfate) H2SO3 (sulfite)

Sulfuric Sulfurous

• H3PO4 (phosphate H3PO3 (phosphite)

Phosphoric Phosphorous

Oxyacid nomenclature ….• HC2H3O2 or CH3COOH (acetate) acetic acid when diluted it is known as

vinegar

• H2CO3 (carbonate) carbonic acid

Arrhenius & Bronsted-Lowry Acids & Bases

According to Arrhenius ….

• An acid is a substance that contains hydrogen & ionizes to produce hydrogen ions (H+) in aqueous solution.

• An base is a substance that contains a hydroxide group and dissociates to produce hydroxide ions (OH-) in aqueous solution.

• Arrhenius acid:HCl (g) → H+

(aq) + Cl-(aq)

the HCl ionizes to produce H+ ions which makes the solution acidic.Arrehenius baseNaOH(s) → Na+

(aq) + OH- (aq)

the NaOH ionizes in water to produce OH - ions to make the solution basic.

According to Bronsted-Lowry…

• An acid is a hydrogen ion or proton donor

• A base is a hydrogen-ion or proton acceptor

Conjugate Acid Base Pairs

• A conjugate acid-base pair consists of two substance related to each other by the donating and accepting of a single hydrogen ion.

Let’s compare!

• The conjugate acid is the species formed when a base accepts a hydrogen ion from an acid.

• The conjugate base is the species that results when an acid donates a hydrogen ion to a base.

Let’s Practice

• Do the practice problems on page 599 of text

Strong acids

• Strong acids ionize completely in water:

that means that their ions remain as ions in water

• Weak acids do NOT ionize completely in water: that means that their ions react to reform their acid in a reversible reaction.

• See page 603 for examples of

strong and weak acid reactions.

Notice the double arrows

Indicating a reversible reaction.

• Strong acids do NOT produce a reversible reaction.

• Weak acids DO produce a reversible reaction.

Strong Acids

• HCl → H+ + Cl –

• H2SO4 → 2H+ + SO4-2

• HNO3 → H+ + NO3-

(note only one arrow in one direction)

WEAK ACIDS

• Produce reversible reactions• Equilibrium reactions

• H3PO4 3H+ + PO4-3

• HC2H3O2 H+ + C2H3O2-

(CH3COOH)

• H2CO3 2H+ + CO3-2

Why Acids?

Acids are important in industry and manufacturing processes.

• H2SO4 -the most commonly produced chemical in the world. Used in petroleum cracking, production of dyes, fertilizers, paints, paper, detergents. Car batteries Dehydration agent (removal of H2O)

• HNO3 Used in making dynamite,

explosives (TNT)

Used in making rubber, plastics,

dyes, & pharmaceuticals

• H3PO4 Flavoring agent in beverages

• HCl - Stomach acid used in digestion process to break up and dissolve food particles & to kill unwanted bacteria Commercially used as a cleaning agent, sold at Home Depot as Muriatic Acid, used to clean brick & concrete.(This is the yellow, sour stuff when you throw up!)

• HC2H3O2 or CH3COOH

diluted 1:10 to make vinegar

A carboxyl acid, because the COOH is called a carboxyl group. It is at the end of a long chain of hydrocarbons.

CH3C= O-OH

Self Ionization of Water

H2 O + H2 O ↔ H3O+ + OH-

{H3O+} =Concentration of hydronium ions is

1 x 10-7 M

{OH- } = Concentration of hydroxide ions is

1 x 10-7 M

Ionization constant (K) for water

• Kw = {H3O+} {OH- } = 1 x 10-14 M2

(1 x 10-7M) (1 x 10-7M) = 1 x 10-14 M2

pH-

• The letters “pH” originated in France and mean

“the power of Hydrogen”

Numerically pH is the negative of the common (base 10) logarithm of the hydronium ion.

pH = - log {H3O+}

pOH = -log {OH-}

Practice Problem

• A 1.0 x 10-4 M solution of HNO3 has been prepared for a laboratory experiment.

a) Calculate the {H3O+} of this solution.

b) Calculate the {OH-}.

Numerically pH & pOH are the negative of the common (base 10) logarithm of the hydronium & hydroxide ions.

pH = - log {H3O+}

-log of 1 x 10-7 = -(-7) = 7

pOH = -log {OH-}

-log of 1 x 10-7 = -(-7) = 7