Chemical Reactions Chapter 3 3.7-3.10. 3.7 Acid and Base Reactions Acids and Bases acids produce carbon dioxide when added to a metal carbonate acids.

Chemical ReactionsChemical Reactions

Chapter 3Chapter 3

3.7-3.103.7-3.10

3.7 Acid and Base Reactions3.7 Acid and Base Reactions

Acids and Bases Acids and Bases acids produce carbon dioxide when added to acids produce carbon dioxide when added to

a metal carbonatea metal carbonate acids often react with metals to produce Hacids often react with metals to produce H22

acids taste sour/bases taste bitteracids taste sour/bases taste bitter strong acids/bases completely ionize in water strong acids/bases completely ionize in water weak acids/bases partially ionizeweak acids/bases partially ionize

Acids and Bases: Arrhenius Acids and Bases: Arrhenius DefinitionDefinition

An acid is a substance that, when An acid is a substance that, when dissolved in water, increases the dissolved in water, increases the concentration of hydrogen ions, Hconcentration of hydrogen ions, H++ (aq), in (aq), in the water.the water.

Acids and Bases: Arrhenius Acids and Bases: Arrhenius DefinitionDefinition

A base is a substance that, when A base is a substance that, when dissolved in water increases the dissolved in water increases the concentration of hydroxide ion, OHconcentration of hydroxide ion, OH--, in the , in the water.water.

ammonia produces hydroxide in water, ammonia produces hydroxide in water, forming ammonium and hydroxide ionforming ammonium and hydroxide ion

common acids and bases on page 132common acids and bases on page 132

Acid and Base ReactionsAcid and Base Reactions

Strong AcidsStrong Acids HCl, HBr, HI, HHCl, HBr, HI, H22SOSO44, HNO, HNO33, HClO, HClO44

Strong BasesStrong Bases Group 1 HydroxidesGroup 1 Hydroxides

• LiOH, NaOH…LiOH, NaOH… Group 2 HydroxidesGroup 2 Hydroxides

• Ca(OH)Ca(OH)22, Sr(OH), Sr(OH)22, Ba(OH), Ba(OH)22

Reactions of Acids and BasesReactions of Acids and Bases

acids react with strong bases to produce a acids react with strong bases to produce a salt and water (ex. hydrochloric acid and salt and water (ex. hydrochloric acid and sodium hydroxide)sodium hydroxide)

net ionic for strong base and strong acid: net ionic for strong base and strong acid: neutralization reactionneutralization reaction

HH++(aq) + OH(aq) + OH-- H H22O (l)O (l)

Acids and Bases: The Bronsted-Acids and Bases: The Bronsted-Lowry DefinitionLowry Definition

An acid is a proton donor.An acid is a proton donor. A base is a proton acceptor.A base is a proton acceptor. Acid-base reactions involve the transfer of Acid-base reactions involve the transfer of

a proton from an acid to a base to form a a proton from an acid to a base to form a new acid and a new base. It is written as new acid and a new base. It is written as an equilibrium reaction and the equilibrium an equilibrium reaction and the equilibrium favors the weaker acid and base. favors the weaker acid and base. can predict favorabilitycan predict favorability

Acids and Bases: The Bronsted-Acids and Bases: The Bronsted-Lowry DefinitionLowry Definition

Acids capable of transferring two or more Acids capable of transferring two or more HH++ ions react with water in multiple steps. ions react with water in multiple steps. Different steps may favor different sides of Different steps may favor different sides of equilibrium.equilibrium. Sulfuric acid is capable of transferring two Sulfuric acid is capable of transferring two

protons. The first step is product-favored but protons. The first step is product-favored but the second step is reactant-favored.the second step is reactant-favored.

Acids and Bases: The Bronsted-Acids and Bases: The Bronsted-Lowry DefinitionLowry Definition

Some substances are Some substances are amphiprotic amphiprotic and can and can function as either an acid or a base. function as either an acid or a base. Water is a typical example.Water is a typical example.

Practice ProblemPractice Problem

Write the balanced, overall equation and Write the balanced, overall equation and the net ionic equation for the reaction of the net ionic equation for the reaction of magnesium hydroxide with hydrochloric magnesium hydroxide with hydrochloric acid.acid.

Oxides of NonmetalsOxides of Nonmetals

Nonmetal oxide + Water Nonmetal oxide + Water Acid Acid Carbon dioxide reacts with water to form Carbon dioxide reacts with water to form

carbonic acid, which then ionizes slightly to carbonic acid, which then ionizes slightly to form hydrogen ion and bicarbonate ion.form hydrogen ion and bicarbonate ion.

Bicarbonate ion can further ionize to form Bicarbonate ion can further ionize to form carbonate. (COcarbonate. (CO22 is an is an acidic oxide acidic oxide))

COCO22 + H + H22O O H H22COCO33

HH22COCO33 H H++ + HCO + HCO33--

HCOHCO33-- H H++ + CO + CO33

2-2-

Oxides of MetalsOxides of Metals

metal oxide + water metal oxide + water base base CaO(s) + HCaO(s) + H22O(l) O(l) Ca(OH) Ca(OH)22(s)(s) oxides of metals are called oxides of metals are called basic oxidesbasic oxides

metal oxide + nonmetal oxide metal oxide + nonmetal oxide salt salt 6CaO(s) + P6CaO(s) + P44OO1010(s) (s) 2Ca 2Ca33(PO(PO44))22(s)(s)

3.8 Gas-Forming Reactions3.8 Gas-Forming Reactions

Formation of a gas: gases may form Formation of a gas: gases may form directly in a double replacement reaction directly in a double replacement reaction or can form from the decomposition of a or can form from the decomposition of a product such as carbonic acid or sulfurous product such as carbonic acid or sulfurous acid (table on page 140)acid (table on page 140) often metal carbonates and acidsoften metal carbonates and acids

Ex. Excess hydrochloric acid solution is Ex. Excess hydrochloric acid solution is added to a solution of potassium sulfite.added to a solution of potassium sulfite.

HH++ + SO + SO33-2-2 H H22OO(l)(l) + SO + SO2(g)2(g)

Classifying Exchange ReactionsClassifying Exchange Reactions

CuCOCuCO33(s) + H(s) + H22SOSO44(aq) (aq) Ba(OH)Ba(OH)22(s) + HNO(s) + HNO33(aq) (aq) CuClCuCl22(aq) + (NH(aq) + (NH44))22S(aq) S(aq)

3.9 Oxidation-Reduction Reactions3.9 Oxidation-Reduction Reactions

These reactions involve the transfer for These reactions involve the transfer for electrons. The oxidation numbers of at electrons. The oxidation numbers of at least two elements must change. These least two elements must change. These may be single replacement, combination, may be single replacement, combination, and decomposition reactions. When a and decomposition reactions. When a problem mentions an acidic or basic problem mentions an acidic or basic solution, it is probably redox. solution, it is probably redox.

Oxidation-Reduction ReactionsOxidation-Reduction Reactions

A substance that loses electrons is A substance that loses electrons is oxidized and is the reducing agent.oxidized and is the reducing agent.

A substance that gains electrons is A substance that gains electrons is reduced and is the oxidizing agent.reduced and is the oxidizing agent.

LEO goes GERLEO goes GER

If one substance is oxidized, another If one substance is oxidized, another substance must be reduced. Hence, substance must be reduced. Hence, redox reactions!redox reactions!

Oxidation-Reduction ReactionsOxidation-Reduction Reactions

2Ag2Ag++ + Cu + Cu 2Ag + Cu 2Ag + Cu+2+2

Oxygen may not be present; but a transfer Oxygen may not be present; but a transfer of electrons results in a charge reduction.of electrons results in a charge reduction.

Silver ion accepts electrons from copper and Silver ion accepts electrons from copper and is reduced to silver (silver ion is the is reduced to silver (silver ion is the oxidizing agent).oxidizing agent).

Copper donates electrons to silver ion and is Copper donates electrons to silver ion and is oxidized to copper (II) ion and is the oxidized to copper (II) ion and is the reducing agent.reducing agent.

Assigning Oxidation StatesAssigning Oxidation States The oxidation state of…The oxidation state of…

an atom in an element is zero (Na, Oan atom in an element is zero (Na, O22)) monatomic ion is same as charge (Namonatomic ion is same as charge (Na++)) fluorine always has an oxidation number of -1fluorine always has an oxidation number of -1 oxygen is usually -2 except for peroxides/fluorineoxygen is usually -2 except for peroxides/fluorine Cl, Br, and I are -1 except with oxygen or fluorineCl, Br, and I are -1 except with oxygen or fluorine hydrogen is +1 in covalent compounds, -1 in binary hydrogen is +1 in covalent compounds, -1 in binary

hydrides, such as NaHhydrides, such as NaH In a compound, the sum must be zero, KMnOIn a compound, the sum must be zero, KMnO44

For ions, sum must equal overall charge, CrFor ions, sum must equal overall charge, Cr22OO77-2-2

Determining Oxidation NumbersDetermining Oxidation Numbers

Assign an oxidation number to the Assign an oxidation number to the underlined atom in each ion or molecule.underlined atom in each ion or molecule. FeFe22OO33

HH22SSOO44

CCOO332-2-

NNOO22--

3.10 Classifying Reactions in 3.10 Classifying Reactions in Aqueous SolutionAqueous Solution

Precipitation Reactions: Ions combine in solution Precipitation Reactions: Ions combine in solution to form an insoluble reaction product.to form an insoluble reaction product.

Acid-Base Reactions: Water is a product of Acid-Base Reactions: Water is a product of many acid-base reactions, and the cation of the many acid-base reactions, and the cation of the base and the anion of the acid form a salt.base and the anion of the acid form a salt.

Gas-Forming Reactions: often involve metal Gas-Forming Reactions: often involve metal carbonates and acidscarbonates and acids

Oxidation-Reduction: NOT ion exchange; Oxidation-Reduction: NOT ion exchange; electrons are transferredelectrons are transferred

HomeworkHomework

After reading Sections 3.7-3.10, you After reading Sections 3.7-3.10, you should be able to do the following…should be able to do the following…

P. 154 (39-48)P. 154 (39-48)