[NOTES] Chapter 4: Three Major Classes of Chemical Reactions

Question 1

Solute

Answer 1

Dissolved in a larger quantity of another

Question 2

Solvent

Answer 2

In an aqueous solution, water served as the solvent

Question 3

Polar Molecule Natures

Answer 3

1) Uneven distribution
2) Bent molecular shape
3) Molecular polarity

the combination of polar bonds and bent shape makes water a polar molecule where the region near the O atom is partially negative (there is a higher electron density) and the region between the H atoms is partially positive (there is a lower electron density)

Question 4

Ionic Compounds Dissolve: Soluble Ionic Compounds

Answer 4

The attractions between each type of ion and several water molecules outweigh the attractions between the ions themselves

Question 5

Ionic Compounds Dissolve: Insoluble Ionic Compounds

Answer 5

The attraction between the cations and anions is greater than the attraction between the ions and water

Question 6

Electrolyte

Answer 6

A substance that conducts a current when dissolved in water
- Soluble ionic compounds are strong electrolytes because they dissociate completely and conduct a large current

Question 7

Nonelectrolytes

Answer 7

Aqueous solutions do not conduct an electrical current

Question 8

Concentration

Answer 8

The quantity of solute dissolved in a given quantity of solution (or of solvent)
- Molarity (M) is the most common unit of concentration
- Molarity = (moles of solute)/(liters of solution) OR M = (mol solute)/(L soln)

Question 9

Precipitation Reaction

Answer 9

Two soluble ionic compounds react to form an insoluble product, a precipitate

The formation of an insoluble product through the net removal of ions from the solution

Question 10

Molecular Equation

Answer 10

Reveals the least about the species that are actually in solution because it shows all the reactants and products as if they were intact, undissociated compounds

Question 11

Total Ionic Equation

Answer 11

Shows all the soluble ionic substances as they actually exist in solution, where they are dissociated into ions

Question 12

Spectator Ions

Answer 12

Not involved in the actual chemical change but are present only as part of the reactants: that is we can’t add a + ion without also adding an anion

Question 13

Net Ionic Equation

Answer 13

Eliminates the spectator ions and shows only the actual chemical change

Question 14

Metathesis (double-displacement reactions)

Answer 14

Reactions in which the reactant ions change partners

Question 15

Acid-Base Reaction (neutralization Reaction)

Answer 15

Occurs when an acid reacts with a base

Question 16

Acid

Answer 16

Substance that produces H+ ions when dissolved in water

Question 17

Base

Answer 17

Substance that produced OH- Ions when dissolved in water

Question 18

Titration

Answer 18

Known concentration of one solution is used to determine the unknown concentration of another

Question 19

Equivalence Point

Answer 19

The amount (mol) of H+ ions in the original volume of acid has reacted with the same amount (mol) of OH- ions from the buret

Question 20

End Point

Answer 20

Occurs when a tiny excess of OH- ions changes the indicator permanently to its basic color

Question 21

Oxidation-Reduction Reaction (Redox)

Answer 21

The net movement of electrons from one reactant to another
- Oxidation: the loss of electrons
- Reduction: the gain of electrons

Question 22

Movement of Electrons Between Reactants

Answer 22

Ionic Compounds: transfer of electrons
Covalent Compounds: Shift of electrons

Question 23

Oxidizing Agent

Answer 23

The species doing the oxidizing (causing electron gain)

Question 24

Reducing Agent

Answer 24

The species doing the reducing (causing the electron loss)

Question 25

Oxidation Number (O.N)

Answer 25

The charge that atom would have if the compound was composed of ions

Question 26

Combining Two Elements

Answer 26

1) Metal and nonmetal form an ionic compound
2) Two nonmetals form a covalent compound

Question 27

Decomposition Redox Reaction

Answer 27

A compound forms two or more products, at least one of which is an element:
Z => X+Y

Question 28

Thermal Decomposition

Answer 28

When the energy absorbed is heat

Question 29

Displacement Reaction

Answer 29

The number of substances on the two sides of the equation remains the same, but atoms (or ions) exchange places
- double displacement (metathesis) reactions where two compounds exchange places, there reactions are not redox processes
- single-displacement reactions where one of the substances is an element; therefore, all single-displacement reactions are redox processes

Question 30

Dynamic Equilibrium

Answer 30

No further changes appear in the amounts of reactants or products
- one the macroscopic level, the reaction is static, but it is dynamic on the molecular level

Question 31

Types of Reversible Reactions

Answer 31

1. Weak Acids in Water
2. Weak Bases in Water
3. Gas-forming Reactions
4. Other Acid-Base and Precipitation Reactions