Acids and Bases

http://www.unit5.org/chemistry/AcidBase.html

http://www.chalkbored.com/lessons/chemistry-11/acid-bronsted.ppt

Properties

electrolytes

turn litmus red

sour taste

react with metals to form H2 gas

slippery feel

turn litmus blue

bitter taste

ChemASAP

vinegar, milk, soda, apples, citrus fruits

ammonia, lye, antacid, baking soda

electrolytes

Acid vs. Base

AcidAcid

pH > 7

bitter taste

does notreact with

metals

pH < 7

sour taste

react withmetals

Alike Different

Related toH+ (proton)

concentration

pH + pOH = 14

Affects pHand

litmus paper

BaseBase

Different

Topic Topic

Common Acids and Bases

Strong Acids (strong electrolytes)

HCl hydrochloric acidHNO3 nitric acidHClO4 perchloric acidH2SO4 sulfuric acid

Weak Acids (weak electrolytes)

CH3COOH acetic acidH2CO3 carbonic

Strong Bases (strong electrolytes)

NaOH sodium hydroxideKOH potassium hydroxideCa(OH)2 calcium hydroxide

Weak Base (weak electrolyte)

NH3 ammonia

Kotz, Purcell, Chemistry & Chemical Reactivity 1991, page 145

Weak Base (weak electrolyte)

NH4OH ammonia

NH3 + H2O NH4OH

Common Acids

Sulfuric Acid H2SO4

Nitric Acid HNO3

Phosphoric Acid H3PO4

Hydrochloric Acid HCl

Acetic Acid CH3COOH

Carbonic Acid H2CO3

Battery acid

Used to make fertilizersand explosives

Food flavoring

Stomach acid

Vinegar

Carbonated water

Common Bases

Sodium hydroxide NaOH lye or caustic soda

Potassium hydroxide KOH lye or caustic potash

Magnesium hydroxide Mg(OH)2 milk of magnesia

Calcium hydroxide Ca(OH) 2 slaked lime

Ammonia water NH3 H2O household ammonia

Name Formula Common Name

.NH4OH

NH41+ + OH1-

ammonium hydroxide

hydroxideion

OH1-

Formation of Hydronium Ions

1+

hydronium ion

H3O+

+

hydrogen ion

H+

water

H2O

1+

(a proton)

1+

Arrhenius Acid

1+

+ +

hydronium ion

H3O+

1-

chloride ion

Cl-

water

H2O

hydrogen chloride

HCl

(an Arrhenius acid)

Any substance that releases H+ ions as the only positive ion in the aqueous solution.

Arrhenius Bases and Their Properties

According to the definition of Arrhenius a:

BaseBase - "a substance whose water solution yields...

Are NaOH and NH3 considered to be Arrhenius bases?

1) Bases are electrolytes

Dissociation equation for NH3

NH3(g) + H2O(l) NH41+(aq) + OH1-(aq)

Dissociation equation for NaOH

NaOH(s) Na1+(aq) + OH1-(aq)

2) Bases cause indicatorsindicators to turn a characteristic color

3) Bases neutralize acidsNaOH(aq) + HCl(aq) NaCl(aq) + H2O(l)

YES

4) Water solutions of bases tasted bitter and feel slippery.

hydroxide ions (OH-) as the only negative ions."

Each of the following unbalanced equations represents a reaction between a Arrhenius acid and base. Identify those in each reaction:

H2CO3 + NH4OH → (NH4)2CO3 + H2O KOH + H3PO4 → K3PO4 + H2O HF + NaOH → NaF + H2O Ba(OH)2 + HNO2 → Ba(NO2)2 + H2O

Brønsted-Lowry Acids and Bases

1+

+

hydronium ion

H3O+

1-

chloride ion

Cl-

(base)

H2O

(acid)

HCl

+ -

Acid = any substance that donates a proton.

Base = any substance that accepts a proton.

Brønsted-Lowry Acids and Bases

1+

+

hydronium ion

H3O+

1-

chloride ion

Cl-

(base)

H2O

(acid)

HCl

+ -

Acid = any substance that donates a proton.

Base = any substance that accepts a proton.

Brønsted-Lowry Acids and Bases

(acid)

H2O

(base)

NH3

+-1+

+

ammonium ion

NH4+

1-

hydroxide ion

OH-

Identify the Bronsted-Lowry acid and the Bronsted-Lowry base in each reaction.

NH4+(aq) + CN- (aq) → HCN (aq) + NH3 (aq)

(CH3)3N(aq) + H2O → (CH3)3NH+(aq) + OH-(aq)

HCHO2(aq) + PO43- → CHO2

-(aq) + HPO42-(aq)

HSO4-(aq) + CO3

2- → SO42- (aq) + HCO3

-(aq)

DefinitionsDefinitions

LewisLewis• AcidsAcids are electron pair acceptors.

• BasesBases are electron pair donors.

Lewis base

Lewis acid

Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

Arrhenius Acids and BasesAcids release hydrogen ions in water.Bases release hydroxide ions in water.

An acid is a substance that produces hydronium ions, H3O+, when dissolved in water.

Lewis DefinitionsA Lewis acid is a substance than can accept (and share) an electron pair.A Lewis base is a substance than can donate (and share) an electron pair.

Lewis Acid

Brønsted-Lowry DefinitionsA Brønsted-Lowry acid is a proton donor; it donates a hydrogen ion, H+.A Brønsted-Lowry base is a proton acceptor; it accepts a hydrogen ion, H+.

Brønsted-Lowry

Arrheniusacids

Acid Definitions

Acid Definitions

Lewis acids

Brønsted-Lowry

Arrheniusacids

The Arrhenius model of acidsand bases was broadened bythe Brønsted-Lowry model.

The Lewis acid-base model isthe most general in scope.

The Lewis definition of an acidincludes any substance thatis an electron pair acceptor;a Lewis base is any substancethat can act as an electron pair donor.

Ralph A. Burns, Fundamentals of Chemistry 1999, page 483

Lewis acids

Brønsted-Lowry

Arrheniusacids

The Arrhenius model of acidsand bases was broadened bythe Brønsted-Lowry model.

The Lewis acid-base model isthe most general in scope.

The Lewis definition of an acidincludes any substance thatis an electron pair acceptor;a Lewis base is any substancethat can act as an electron pair donor.

Ralph A. Burns, Fundamentals of Chemistry 1999, page 483

Acid Definitions

Acid – Base Systems

Type Acid Base

Arrhenius H+ or H3O + producer

OH - producer

Brønsted-

Lowry

Proton (H +) donor

Proton (H +) acceptor

Lewis Electron-pair acceptor

Electron-pair donor