Modern ChemistryChapter 14

Acids & Bases

Section 1Properties of Acids & Bases

• Aqueous solutions of acids taste sour.

• Acids change the color of acid-base indicators.

• Some acids react with active metals and release hydrogen gas.

• Acids react with bases to produce salts and water.

• Acids conduct electricity (electrolytes).

Common acids

• Name some items with a sour taste, and it is usually an acid or has an acid as an ingredient.

Binary Acids

• A binary acid is an acid that contains only hydrogen and one of the more electronegative elements. (group 17 elements primarily)

Binary Acid Nomenclature

• Naming binary acids:– The name of a binary acid begins with the prefix

“hydro”.– The root of the name of the second element follows

this prefix.– The name then ends with the suffix “ic”.

• HF = hydrofluoric acid• HCl = hydrochloric acid• HBr = hydrobromic acid• HI = hydroiodic acid• H2S = hydrosulfuric acid

Acid Nomenclature Practice• Write the formula for the following binary acids

1) hydrochloric acid

2) hydroiodic acid

• Name the following binary acids:

1) HBr(aq)

2) H2S(aq)

3) HF(aq)

Oxyacids & Nomenclature

• An oxyacid is an acid that is a compound of hydrogen, oxygen, and a third element, usually a nonmetal.

• Nomenclature of an oxyacid.– Determine the name of the polyatomic ion combined

with the hydrogen.– If the name of the ion ends with “ate”, replace it with

“ic” and add the word acid.– If the name of the ion ends with “ite”, replace it with

“ous” and add the word acid.• For example for HNO3, NO3

1- = nitrate, so the name of the acid is nitric acid.

• Also for HNO2, NO21- = nitrite, so the name of the acid is nitrous

acid.

Acid Nomenclature Practice

• Name the following oxyacids:• H2SO4 (aq)

• H2SO3 (aq)

• HClO (aq)

• HClO2 (aq)

• HClO3 (aq)

• HClO4 (aq)

• HC2H3O2 (aq)

Acid Nomenclature Practice• Write the formula for the following acids:

• phosphoric acid

• phosphorous acid

• nitrous acid

• nitric acid

Common Industrial Acids

• Sulfuric acid (H2SO4) is the most commonly produced industrial chemical and is used in petroleum refining, metallurgy, and is used in the production of fertilizer, metals, paint, dye, paper & detergents. It is also used in car batteries.

Common Industrial Acids

• Nitric acid (HNO3) stains proteins (like those in your skin) yellow. It is used in the manufacture of explosives, plastics, and pharmaceuticals.

Common Industrial Acids

• Phosphoric acid (H3PO4) is used primarily in the manufacture of fertilizers and animal feed. It is also used as a flavoring for beverages.

Common Industrial Acids

• Hydrochloric acid (HCl) is the acid produced by the stomach for digestion. It is also called muriatic acid and is used to clean masonry and maintain the acidity of swimming pools.

Common Industrial Acids

• Acetic acid (HC2H3O2) is the active ingredient in vinegar and is produced by the fermentation of certain plants. It is used as a flavoring agent, a preservative, and as a fungicide. It is also used in the manufacture of plastics.

Properties of Bases

• Aqueous solutions of bases taste bitter.

• Dilute aqueous solutions of bases feel slippery.

• Bases change the color of acid-base indicators.

• Bases react with acids to produce salts & water.

• Bases conduct electricity (electrolytes).

Base Nomenclature

• All bases contain the hydroxide (OH) ion.

• Most bases also contain a metallic ion.

• The number of hydroxide ions is determined by the charge of the metal ion.

• Na+ + OH- NaOH

• Ca2+ + OH- Ca(OH)2

• Al3+ + OH- Al(OH)3

Base Nomenclature

• Naming bases is VERY difficult.– Name the cation.– Add “hydroxide”.

Ba(OH)2 = barium hydroxide

NH4OH = ammonium hydroxide

KOH = potassium hydroxide

Arrhenius Acids & Bases

• An Arrhenius acid is a chemical compound that increases the concentration of hydrogen, H+ (hydronium, H3O+) ions in an aqueous solution.

• An Arrhenius base is a chemical compound that increases the concentration of hydroxide (OH-) ions in an aqueous solution.

Acid & Base Strength

• A strong acid is one that ionizes completely in an aqueous solution.

• A weak acid is an acid that releases few hydrogen ions in an aqueous solution.

• A strong base, like a strong acid, is one that completely dissociates to produce hydroxide ions in an aqueous solution and acts as a strong electrolyte.

• A weak base is a weak electrolyte that produces few hydroxide ions and is usually not very soluble in water.

– Do section review questions #1 through 5 on page 476.

Cross-Disciplinary Connection

• Read the Cross-Disciplinary Connection entitled “Acid Water-A Hidden Menace” on page 477.

• Answer the three questions at the end of the article.

Section 2Acid-Base Theories

• Bronsted-Lowry acid is a molecule or ion that is a proton (H+) donor.

• Bronsted-Lowry base is a molecule or ion that is a proton acceptor.

• A monoprotic acid can donate only one proton (H+) per molecule.

• A polyprotic acid can donate more than one proton per molecule.– diprotic acid can donate 2 protons, such as H2SO4

– triprotic acid can donate 3 protons, such as H3PO4

Lewis Acids & Bases

• A Lewis acid is an electron pair acceptor.

• A Lewis base is an electron pair donor.

Section 3Acid-Base Reactions

• A conjugate base is the species that remains after a Bronsted-Lowry acid gives up a proton.

• A conjugate acid is the species that is formed when a Bronsted-Lowry base gains a proton.

– For the reaction HF + H2O F- + H3O+ – the F- is the conjugate base and the H3O+ is the

conjugate acid.

Neutralization Reaction

• A neutralization reaction is the reaction between an acid and a base to produce a salt and water.

HCl + NaOH NaCl + H2O

• neutralization is the reaction of a hydronium (H3O+) and a hydroxide (OH-) ion to form a water molecule.

H3O+ + OH- 2 H2O

• A salt is an ionic compound composed of a cation from a base and an anion from an acid.

Na+ + Cl- NaCl

Acid Rain

• Gaseous byproducts of industrial processes enter the atmosphere and combine with water to produce an acid that the falls as acid rain.

SO2 + H2O H2SO3

SO3 + H2O H2SO4

NO + H2O HNO2

NO2 + H2O HNO3

Modern Chemistry Chapter 14 Test Review

• 35 multiple choice questions– properties of acids and bases (9)– definition, naming & identification of binary and oxyacids (5)– determining formulas of oxyacids from their names (3)– names and uses of the common industrial acids; sulfuric, nitric,

hydrochloric, phosphoric, and acetic (6)– definitions and identification of Arrhenius acids & bases (3)– definitions of weak & strong acids (1)– identify diprotic & triprotic acids (2)– definition of Bronsted-Lowry acids & bases (2)– definition of Lewis acids & bases (2)– definition of conjugate acids & bases (2)