Transcript Chem Final Review (Spring)

Final Chemistry Review
Stuff you Should Know:
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Ionic vs. Covalent bonds
Writing reactions and balancing them
Types of Radioactive decay
Structure of the Atom
STP
Half-life
Equilibrium
Moles/Molecules/Atoms in a substance
Molecular shapes
Atomic radius and other periodic trends
Ions and Ions Charges
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Stuff You Should Review
Catalysis and Activation Energy
Calculating pH, pOH, [H+], and [OH-]
Measuring Reaction Rates
Gas Laws
Acid/Base reactions
Solubility
Organic Chemistry Naming and Functional Groups
Arrhenius Acids/Bases vs. Brownstein-Lowry
Acids/Bases
Types of Solutions
Specific Heat of a substance
Enthalpy and Entropy
Stuff You Should Review
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Molality
Exothermic vs. Endothermic
Electrochemical cells
Phases change diagrams
Structural and Geometric Isomers
Electrolysis
Titrations and Neutralization Points
Laboratory Procedures
Determining spontaneity
Calculating Oxidation Numbers
Oxidation-Reduction Reactions
• What are the oxidation numbers for the elements?
A) Na2SO4
B) K2Cr2O7
Na= +1
O= -2
0= (+1)2 + X + (-2)4
X= +6; S= +6
C) HClO2
H= +1, O=-2, Cl= +3
K= +1 O=-2
0= (+1)2 + 2(X) + (-2)7
X= +6; Cr= +6
D) (NH4)2SO4
H=+1, O=-2, N= -3, S= +6
Oxidation-Reduction Reactions
• What is a redox reaction?
A chemical reaction where there is a transfer of electrons
• How do you know if an element is oxidized or reduced?
If an element is oxidized it will lose electrons through the
reaction
If an element is reduced it will gain electrons through the
reaction
• How does “OIL RIG” help us with redox reactions?
Oxidation
If
Loses
Reduced
If
Gaines
• What is a reducing agent/oxidizing agent?
Reducing agent- element that is oxidized in the reaction
Oxidizing agent- element that is reduced in the reaction
Practice
Are the following redox reactions?
What is oxidized? What is reduced?
Remember
OIL RIG
1) Ag + H2S + O2  Ag2S + H2O
Ag: 0+1; Oxidized O: 0-2; Reduced H: +1 +1
2) HCl + NaOH  NaCl + H2O
H: +1+1 Cl: -1 -1 Na: +1 +1 O: -2  -2
3) C6H12O6 + O2 CO2 + H2O
H: +1 +1 C: 0+4; Oxidized O: -2 -2; 0-2; Reduced
4) NaOH + Cl2  NaCl + NaClO + H2O
Na: +1+1 H: +1+1 O:-2 -2 Cl: 0-1; Reduced
0+1; Oxidized
Practice
For the following label the oxidizing/reducing
agents
1) H2 + F2 → 2 HF
H: 0 +1; Oxidized, reducing agent
F: 0 -1; Reduced, oxidizing agent
2) Cr2O3 + Al ----> Cr + Al2O3
Al: 0+3; Oxidized, reducing agent
Cr: +30; Reduced, oxidizing agent
3) 4 Al + 2O2  2Al2O3
O: 0  -2; Reduced, oxidizing agent
Al: 0  +3; Oxidized, reducing agent
Electrochemistry
• What is electrolysis?
Using an energy source, like a battery, to drive a nonspontaneous chemical reaction
• Label the electrochemical cell:
Electrolytic Cell
• If the following compound was separated using
electrolysis: 2Al2O3  4Al(s) + 3O2(g)
1) What is oxidized/reduced?
Al; +30, reduced
O; -20, oxidized
2) What are the cations/anions?
Al+3Cation
O-2Anion
3) What elements will move to the cathode/anode?
Al+3Cathode
O-2Anode
Electrochemistry
• What 3 ways we can use electrolysis?
Refining Ores- remove pure metal from compounds found
in the Earth
Electroplating- cheap and effective why to coat and protect
reactive metals
Electrolytic Cleaning- restoring aged materials
• Explain what is happening in this picture:
Aluminum is being refined from
bauxite ore. After heating to
remove impurities, electrolysis is
used to remove Al3+ from AL2O3. O2ions are attracted to the Carbon
anodes, while the Al3+ ions join to
make liquid aluminum which sinks
to the bottom
Electrochemistry
• In an electrochemical cell, how do you know which
metal will be the anode and which will be the
cathode?
The metal more easily reduced will be the cathode and the
metal more easily oxidized will be the anode.
In an Fe/Pb battery
which metal is the
anode/cathode?
Fe is the anode
Pb is the cathode
Electrochemistry
• What 2 factors give a battery its voltage?
1) The amount of metal (surface area) in the battery
2) The potential difference between the metals used
• In the following battery:
• What is the anode/cathode?
Mg= anode; Cu= cathode
What is the connection tube
called and what does it do?
Salt bridge; it allows the transfer of
ions that build up at both the
anode and cathode
Thermochemistry
• What are systems and surroundings and how do
they connect to thermochemistry?
A system is anything being observed/tested and the
surroundings are the objects/area the system connects
with. Studying how energy/heat moves between the
system and its surrounds is the base of thermochemistry
• What is enthalpy (H) and what does a positive (+ΔH)
or negative (-ΔH) change in enthalpy mean?
Enthalpy is the potential heat energy within a substance or
system.
+ΔH energy is being absorbed into the system from the
surroundings endothermic
-ΔH energy is being released into the surroundings from
the system exothermic
Thermochemistry
• What are 3 major differences between exothermic and
endothermic reactions?
1) Endothermic energy is a reactant
Exothermic energy is a product
2) Endothermic products have more energy than the reactants
Exothermic reactants have more energy than the products
3) Endothermic energy must be constantly supplied
Exothermic energy must be supplied until reaction is selfsustaining
• How do catalysts lowers activation energy?
Catalysts increase the chance the molecules in the reaction will
meet and react; which means the reaction is more efficient. Less
energy is need to run the reaction because the less energy is
wasted on the “randomness” of the molecules meeting to react
Thermochemistry
• What are the two forces that determine if a reaction is
spontaneous or not?
1) Enthalpy heat normally flows from high concentration to
low concentration
2) Entropy systems normally move from order to disorder
• How do can you tell that entropy is increasing in a
chemical reaction?
In a reaction is the # of moles /# of molecules increases then the
entropy is increasing.
2H2O 2H2 + 2O2
2:4
Also if a phase change occurs where the new phase is a higher
energy state the if pervious then the entropy is increasing.
solidliquidgas
Thermochemistry
• What is the specific heat capacity of water?
4.184J/g∙Co
• What is the specific heat of a substance that absorbs
2.5 x 103 joules of heat when a sample of 1.0 x 104 g of
the substance increases in temperature from 10.0oC to
70.0oC?
C= 2.5x103/(1.0X104)(60)
C= q/mΔT
-3 J/g∙Co
=
4.2
X10
3
q= 2.5 x10 J
m= 1.0 x104g
ΔT= 70-10=60oC
Thermochemistry
• What law explains why the change in the temperature of the
water inside a calorimeter must equal the amount of energy
released/absorbed in the chemical reaction you are testing?
The Law of the Conservation of Energy; since energy cannot be
created/destroyed, any energy put into/taken out of the water is the
result of the breaking/making of chemical bonds during the reaction
• A 1.75 g sample of acetic acid, CH3CO2H, was burned in oxygen in
a calorimeter. The calorimeter contained 925 g of water its
contents increased from 22.2oC to 26.5oC. What is the molar heat
of combustion of acetic acid?
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qwater= (mwater)(ΔT)(Cwater)  (925g)(26.5-22.2)(4.184)
qwater= 16,641.86 J
qreaction= - qwater  -16,641.86 J
60.5g CH3CO2H
qreaction= -16,641.86__________
= -575,303 J/mol
1.75 g CH3CO2H
1mol CH3CO2H
Organic Chemistry
• What is the difference between alkanes, alkenes, and
alkynes?
Alkanes hydrocarbons with only single bonds
Alkenes hydrocarbons with at least one double bond
Alkynes hydrocarbons with at least on triple bond
• What is a structural isomer?
Substances that have the same molecular formula but different
structures and thus have different names
Organic Chemistry
• What do ring hydrocarbons always start with when
named?
“cyclo-”
• What is an aromatic hydrocarbon?
A hydrocarbon that contains a benzene ring
• What is a geometric isomer?
A substances that have similar structures and names but have
different positions around a double bond
Cis large complexes are on the same side
Trans large complexes are on the opposite sides
Practice Naming Alkanes
CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
nonane
3-ethylhexane
5-(1-methylpropyl)decane
cyclopropylcyclopentane
(2,2-dimethylpropyl)
cycloheptane
Practice Naming Alkenes
2-ethlyhexene
trans-2-pentene
cis-3-(1-methylethyl)-2hexene
cyclopentene
Practice Naming Alkynes
5-methly-2-hexyne
4-methyl-1,5-octadiyne
5-ethyl-2-methyl-3-heptyne
2-methyl-3-hexyne
Organic Chemistry
• What is a functional group?
Any substance added to a hydrocarbon that changes its chemical
properties
• What is an addition reaction?
Breaking of double or triple bonds
to add things to a hydrocarbon
• What is a condensation reaction?
Removing a hydroxyl (-OH) and H ion
to bind to chains together with
H2O made as a by-product
Organic Chemistry
• What is the difference between thermoplastics and
thermosetting plastics?
Thermoplastics can be melted down and recycled to new
products while thermosetting plastics are not commonly recycled
because crosslinking can make them difficult to meltdown.
• Name the functional group:
Halogen
Ether
Amine
Alcohol
Carboxylic acid
Ketone
Amide
Aldehyde
Ester