43CHEM107 Final Exam Review
Chapter 7:
Thermodynamics: determines if a reaction will occur spontaneously but tells us nothing about
the amount of time the reaction will take.
Kinetics: the study of the rate (or speed) of chemical reactions.
Exothermic Reactions:
-Heat released by reaction is absorbed by the surrounding solution
-To be an Exothermic reaction requires a net release of energy (ΔH)
Combustion - CH4(g) + 2O2(g) CO2(g) + 2H2O(g) + 211 kcal
Endothermic Reactions:
-Reactants absorb heat from the surrounding solution
-Reaction takes place slowly due to the large activation energy required
-The energy of the products is greater than that of the reactants
Decomposition - 22 kcal + 2NH3(g) N2(g) + 3H2(g)
Equilibrium reactions
-Chemical reactions that do not go to completion
2
[ H F ]
Keq=-Products on top2
[Heactants on 2][F2]-R
bottom
•No solids or liquids are present
•All reactants and products appear in the expression
•Numerator term is the product term [HF]2
•Denominator term is the reactants [H2] and [F2]
•Each term contains an exponent identical to the corresponding coefficient in the
balanced equation.
•The brackets represent molar concentration (M)
Theoretical rate law
-Cares about the reactants
Effect of heat:
Exothermic reactions: treat heat as a product
-Addition of heat is treated as increasing the amount of product
-More product shifts equilibrium to the left
-Increases amount of reactants
-Decreases amount of product
Endothermic reaction: treat heat as a reactant
-reaction will shift to the right if heat is added by increasing the temperature
effect of pressure:
-Pressure affects the equilibrium only if one or more substances in the reaction are gases
-Relative number of gas moles on reactant and product side must differ
-When pressure goes up, shift to side with less moles of gas
-When pressure goes down, shift to side with more moles of gas
Effect of a catalyst:
-A catalyst has no effect on the equilibrium composition
-It increases the rate of both the forward and reverse reaction to the same extent
-While equilibrium composition and concentration do not change, equilibrium is reached
in a shorter time
Catalyst:
-A substance that increases the reaction rate
-Undergoes NO net change
-Is NOT used up at the end of a reaction
-Does not alter the final product of the reaction
-Does NOT interact with the reactants to create the same pathway for product
production
Factors that affect the rate of a reaction:
1.Structure of the reacting species
2.Molecular shape and orientation
3.Concentration of reactants
4.Temperature of reactants
5.Physical state of reactants
6.Presence of a catalyst
-Rate will increase as concentration increases
-Rate increases as temperature increases
-A catalyst increases the reaction rate
Interpreting equilibrium constants:
1.K greate3eqr than 1 10
•Large value of Keq indicates numerator (product term) >>> denominator (reactant
term)
•At equilibrium mostly product present
2.K less than 1 10–3eq
•Small value of Keq indicates numerator (product term) <<< denominator (reactant
term)
•At equilibrium mostly reactant present
3.Kq between 1 10–3 a3end 1 10
•Equilibrium mixture contains significant concentration of both reactants and
products
If k is less than 1 reactants are favored
If k is greater than 1 products are favored
If k is = to 1 neither reactants or products are favored
Chapter 8:
Slides 1-31
Acids: Taste sour, dissolve some metals, cause plant dye to change color
Bases: Taste bitter, are slippery, are corrosive
Arrhenius Acid:
A substance, when dissolves in water, dissociates to produce hydrogen ions:
-Hydrogen ion: H+ also called “proton”
-HCl is an acid:
-HCl(aq) H¿−
+¿aq) + Cl(aq)
Arrhenius Base:
A substance, when dissolves in water, dissociates to produce hydroxide ions, OH-
-NaOH is a base
-NaOH(aq) Na+(aq) + OH-(aq)
Brønsted-Lowry Acid
Proton (H+) donor
These are not defined using water
Brønsted-Lowry Base
Proton (H+) acceptor
Conjugate Acid – what the base becomes after it accepts a proton
•HY+ is the conjugate acid of the base Y
Conjugate Base – what the acid becomes after it donates its proton
Strong Acids:
•HCl, HBr, HI – hydrochloric acid, etc.
•HNO3 – Nitric acid
•H2SO4 – Sulfuric Acid
•HClO4 – Perchloric Acid
Strong Bases:
•NaOH, KOH, Ba(OH)2
•All metal hydroxides
The pH of a solution is defined as:
pH = −log[H+3O]
pH + pOH = 14
1.0x10-14= [H+] + [OH-]
pH scale:
Chapter 10:
First 10 alkane hydrocarbons:
NameMolecular Formula
Alkanes CnH2n+2
Methane CH4
Ethane C2H6
Propane C3H8
Butane C4H10
Pentane C5H12
Hexane C6H14
Heptane C7H16
Octane C8H18
Nonane C9H20
Decane C10H22
Alkanes are saturated hydrocarbons:
-Contain only one carbon and hydrogen
-Bonds are carbon-hydrogen and carbon-carbon single bonds
Physical properties of hydrocarbons
Condensed Formula
CH4
CH3CH3
CH3CH2CH3
CH3CH2CH2CH3 or CH3(CH2)2CH3
CH3CH2CH2CH2CH3 or CH3(CH2)3CH3
CH3CH2CH2CH2CH2CH3 or CH3(CH2)4CH3
CH3CH2CH2CH2CH2CH2CH3 or CH3(CH2)5CH3
CH3CH2CH2CH2CH2CH2CH2CH3 or CH3(CH2)6CH3
CH3CH2CH2CH2CH2CH2CH2CH2CH3 or CH3(CH2)7CH3
CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3 or CH3(CH2)8CH3
1.Nonpolar molecules
2.Not water soluble; soluble in nonpolar organic solvents
3.Low melting points and low boiling points
4.Generally less dense (lighter) than water
5.As length (molecular weight) increases, melting and boiling points increase as does the
density
Molecular formula
-Gives you the least amount of information about the structure
Condensed formula
-Gives you more info about the structure than molecular formula
-Where it starts to take shape
Expanded formula
-Represents the structure fully
-Gives you the most information
Line structure formula
-Every carbon represents a point
**CH4 is the simplest organic compound – cannot be broken down any further
Cycloalkane structures:
Alkane – one bond
Alkene – double bond
Alkyne – triple bond
Hydrogenation – produces an alkane (addition of a molecule of hydrogen)
-Platinum, palladium, or nickel required as catalyst
Halogenation – produce an alkane (addition of a molecule of halogen (X2))
-Does NOT require a catalyst
Hydration – produces an alcohol (adding a water molecule to an alkene)
-Strong acid as catalyst
Halohydration – produces an alkyl halide (alkene combined w a hydrogen halide such as HBr or
HCl)
-Does NOT require a catalyst
Equilibrium reactions do NOT go to completion
