[NOTES] Chapter 4: Three Major Classes of Chemical Reactions Flashcards
Solute
Dissolved in a larger quantity of another
Solvent
In an aqueous solution, water served as the solvent
Polar Molecule Natures
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)
Ionic Compounds Dissolve: Soluble Ionic Compounds
The attractions between each type of ion and several water molecules outweigh the attractions between the ions themselves
Ionic Compounds Dissolve: Insoluble Ionic Compounds
The attraction between the cations and anions is greater than the attraction between the ions and water
Electrolyte
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
Nonelectrolytes
Aqueous solutions do not conduct an electrical current
Concentration
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)
Precipitation Reaction
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
Molecular Equation
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
Total Ionic Equation
Shows all the soluble ionic substances as they actually exist in solution, where they are dissociated into ions
Spectator Ions
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
Net Ionic Equation
Eliminates the spectator ions and shows only the actual chemical change
Metathesis (double-displacement reactions)
Reactions in which the reactant ions change partners
Acid-Base Reaction (neutralization Reaction)
Occurs when an acid reacts with a base
Acid
Substance that produces H+ ions when dissolved in water
Base
Substance that produced OH- Ions when dissolved in water
Titration
Known concentration of one solution is used to determine the unknown concentration of another
Equivalence Point
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
End Point
Occurs when a tiny excess of OH- ions changes the indicator permanently to its basic color
Oxidation-Reduction Reaction (Redox)
The net movement of electrons from one reactant to another
- Oxidation: the loss of electrons
- Reduction: the gain of electrons
Movement of Electrons Between Reactants
Ionic Compounds: transfer of electrons
Covalent Compounds: Shift of electrons
Oxidizing Agent
The species doing the oxidizing (causing electron gain)
Reducing Agent
The species doing the reducing (causing the electron loss)
Oxidation Number (O.N)
The charge that atom would have if the compound was composed of ions
Combining Two Elements
1) Metal and nonmetal form an ionic compound
2) Two nonmetals form a covalent compound
Decomposition Redox Reaction
A compound forms two or more products, at least one of which is an element:
Z => X+Y
Thermal Decomposition
When the energy absorbed is heat
Displacement Reaction
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
Dynamic Equilibrium
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
Types of Reversible Reactions
- Weak Acids in Water
- Weak Bases in Water
- Gas-forming Reactions
- Other Acid-Base and Precipitation Reactions
