Chapter 4

CHAPTER 4CHAPTER 4Aqueous Reactions and Aqueous Reactions and Solution StoichiometrySolution Stoichiometry

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GENERAL PROPERTIES OF GENERAL PROPERTIES OF AQUEOUS SOLUTIONSAQUEOUS SOLUTIONS

A A solutionsolution is a homogeneous is a homogeneous mixture of two or more pure mixture of two or more pure substances.substances.

In a solution, the solute is dissolved in the solvent.

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An An electrolyteelectrolyte is a substance that dissociates is a substance that dissociates into ions when dissolve in water. into ions when dissolve in water.

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A A nonelectrolytenonelectrolyte is a substance that does not is a substance that does not dissociate into ions when dissolved in water. dissociate into ions when dissolved in water.

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A A strong electrolytestrong electrolyte exists in solution exists in solution completely or nearly completely as ions.completely or nearly completely as ions.

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A A weak electrolyteweak electrolyte is a solute that exists in is a solute that exists in solution mostly in the form of molecules. solution mostly in the form of molecules.

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PRECIPITATION REACTIONSPRECIPITATION REACTIONS

A reaction that results in the formation of an A reaction that results in the formation of an insoluble product is called a insoluble product is called a precipitation precipitation reactionreaction

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In order to write an accurate equation for a In order to write an accurate equation for a precipitation reaction, you need to follow these precipitation reaction, you need to follow these steps:steps:

1) Write a balanced molecular equation. 2) Dissociate all strong electrolytes. 3) Cross out the spectator ions. 4) Write the net ionic equation with whatever is left over.

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ACID-BASE REACTIONSACID-BASE REACTIONS

AcidsAcids are substances that ionize in aqueous are substances that ionize in aqueous solution to form hydrogen ions. solution to form hydrogen ions.

There are seven strong acids:• Hydrochloric (HCl)• Hydrobromic (HBr)• Hydroioidic (HI)• Chloric (HClO3)• Perchloric (HClO4)• Nitric (HNO3)• Sulfuric (H2SO4)

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BasesBases are substances that accept H are substances that accept H++ ions and ions and produce hydroxide (OHproduce hydroxide (OH--) ions when they dissolve ) ions when they dissolve in water. in water.

The strong bases are the soluble metal salts of the hydroxide ion:• Alkali metals• Calcium• Strontium• Barium

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In an acid-base reaction, the acid donates a proton In an acid-base reaction, the acid donates a proton (H(H++) to the base. ) to the base.

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When a solution of an acid and a solution of a When a solution of an acid and a solution of a base are mixed, a base are mixed, a neutralization reactionneutralization reaction occurs. occurs.

HCl (aq) + NaOH (aq) → H2O (l) + NaCl (aq)When a strong acid and a strong

base are mixed, water and a salt are produced.

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Some reactions can occur between acids and Some reactions can occur between acids and other species that produce a gas. other species that produce a gas.

CaCO3 (s) + HCl (aq) →CaCl2 (aq) + CO2 (g) + H2O (l)

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OXIDATION-REDUCTION OXIDATION-REDUCTION REACTIONSREACTIONS

A reaction in which electrons are transferred is A reaction in which electrons are transferred is called an called an oxidation-reductionoxidation-reduction, or redox, , or redox, reactionreaction. .

Loss of electrons is called oxidation.

The gain of electrons is called reduction.

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The rules for assigning oxidation numbers are as follows:1. For an atom in its elemental form, the

oxidation number is always zero.2. For any monatomic ion, the oxidation

number equals the charge on the ion.3. Nonmetals usually have negative oxidation

numbers, although they can sometimes be positive.

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4. The oxidation number of oxygen is usually -2, except in the peroxide ion (O2

2-) when it is -1.

5. The oxidation number of hydrogen is +1 when it is bonded to nonmetals and -1 when it is bonded to metals.

6. The oxidation number of fluorine is always -1

7. The sum of the oxidation numbers in a neutral compound is zero. The sum of the oxidation numbers in a polyatomic ion equals the charge on the ion.

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In order to determine whether or not a single-In order to determine whether or not a single-replacement reaction will occur, you need to replacement reaction will occur, you need to look at the activity series of the elements. look at the activity series of the elements.

Any metal on the list can be oxidized by the ions of elements below it.

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CONCENTRATIONS OF SOLUTIONSCONCENTRATIONS OF SOLUTIONS

Molarity (M) expresses the concentration of a solution as the number of moles of solute in a liter of solution (soln):

moles of solutevolume of solution in litersMolarity (M) =

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CONCENTRATIONS OF SOLUTIONSCONCENTRATIONS OF SOLUTIONS

To make a dilution of a solution with a known To make a dilution of a solution with a known molarity, a simple equation is used:molarity, a simple equation is used:

Mconc x Vconc = Mdil x Vdil

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SOLUTION STOICHIOMETRY AND SOLUTION STOICHIOMETRY AND CHEMICAL ANALYSISCHEMICAL ANALYSIS

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SOLUTION STOICHIOMETRY AND SOLUTION STOICHIOMETRY AND CHEMICAL ANALYSISCHEMICAL ANALYSIS

Titration is Titration is an an analytical analytical technique in technique in which one which one can can calculate calculate the the concentratioconcentration of a solute n of a solute in a in a solution.solution.

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Chapter 4

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