1. ELECTROCHEMISTRY
REDOX REACTION
Oxidation-Reduction Reaction
o Electron transfer reaction and a coupled
reaction (oxidation and reduction)
LEORA
(Loss of Electron - Oxidation - Reducing Agent)
GEROA
(Gain of Electron - Reduction - Oxidizing Agent)
Electrochemical Cells
o devices that make use of the inter-conversion of
electrical and chemical energy.
1. Galvanic or Voltaic Cells
o generate electricity from spontaneous reactions
(chemical energy ⟶ electrical energy)
2. Electrolytic Cells
o use electric current from non-spontaneous
reaction for certain chemical reactions to
occur (electric energy ⟶ chemical energy)
GALVANIC/VOLTAIC CELLS
Parts of a Galvanic Cell
o Anode – negative electrode and where electrons
produced accumulate
o Cathode – positive electrode
o Anolyte – electrolyte solution where anode is
immersed
o Catholyte – electrolyte solution where cathode is
immersed
o Anions - flow towards the anolyte to neutralize
the charge of cation that accumulates after
oxidation
o Cations – flow towards the catholyte to
neutralize the anion
o Internal Circuit – consists of electrolyte in the
salt bridge to maintain electrical neutrality
o Voltmeter – measures the cell potential
Redox Process
o Oxidation – occurs at the anode (loss of
electron)
o Electrons – moves from anode to cathode
through the external wire
o Reduction – occurs at the cathode (gain of
electron)
Electromotive Force (emf)
o cell voltage or cell potential
o tendency of the cell reaction to occur
o measured using the voltmeter
Standard Electrode Potential
o Ionic Concentration – 1.0 M
o Gases – 1.0 atm pressure
o Temperature – 25°C or 298.15 K
o summarized in the standard reduction
potential table
Standard Reduction Potential Table
o written as reduction half reactions
o reverse to get the oxidation half reaction and
change the sign of the potential
o multiplying the reaction will not change the value
of the potential
Computation
o balance the number of electrons by multiplying
o add the oxidation potential and reduction
potential to get the overall cell potential
ELECTROLYTIC CELLS
Electrolysis – process where electric current passes
through a solution to produce a chemical change
Electrolytic cell – current source that serves as an
electron pump that pushes electrons from anode to
the cathode
Anode – positively charged, saps the electrons, and
where oxidation occurs (attracts negative ions)
**There is no potential given to non-aqueous solution.
Electrolysis of Aqueous Solutions
o Water could be oxidized or reduced
o Use experimental observations as basis to know
what reaction will be oxidized or reduced
o In absence of experimental observations, the
reaction with higher potential will occur
Cathode – negatively charged, where electrons
accumulate, and where reduction occurs (attracts
positive ions)
SUMMARY OF GALVANIC AND ELECTROLYTIC CELLS
CHEMISTRY OF BATTERIES
Battery – electrochemical cell that provides electric energy from a chemical reaction (galvanic cell)
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Development of Batteries
Baghdad’s Battery (1938) – Director of the
8. Georges Leclanche – invented the Leclanche
Baghdad Museum found what is now referred to
cell
as the Baghdad Battery in the basement of the
9. Carl Gassner (1887) – invented the first dry cell
museum. Analysis dated it at around 250BC and
battery
of Mesopotamian origin.
10. Waldmar Jungner (1899) – invented the nickel
Benjamin Franklin (1749) – coin the term
cadmium battery along with nickel-iron battery in
battery. This is the term he used to describe
1899. The Nickel-Cadmium battery was not
linked capacitors.
widely available for consumer use until 1947.
Alessandro Volta - Fabricated the first
11. Thomas Edison (1903) – patented a slightly
functional battery (the voltaic pile)
modified design of Jungner’s nickel-iron battery.
John Frederic Daniell (1836) – invented
12. Lewis “Lew” Urry (1949) - introduced the
Daniell cell to overcome some challenges in the
common alkaline battery at the Eveready Battery
voltaic pile.
company.
William Robert Grove – invented the Grove
13. M. Stanley Whittingham (1970) – proposed the
cell
Lithium-ion battery while working for Exxon. In
Gaston Plante (1859) - invented the first
1991, Sony and Asahi Kasei released the first
rechargeable battery, the lead acid battery.
commercial lithium-ion battery.
Callaud (1860s) – created the Gravity cell
Different Types of Batteries
Energy Generated from a Battery
o Alkaline batteries – 1.5 V
o Capacity – ability to sustain the flow of
electrons longer because they contain more
material (in the units of mAh or milliampere
hour)
o Larger cells have greater capacity but voltage
remains the same
2. NUCLEAR CHEMISTRY
NUCLEAR CHEMISTRY
It is a study of radioactive substances and deals with changes in matter originating in the nucleus of an atom.
Nucleus – comprised of 2 nucleons, protons (p+) and
neutrons (n0)
Isotopes – atoms of the same element but different
number of neutrons
Nuclear vs Chemical Reaction
Nuclear Binding Energy
o powerful short-range force that holds the p+ and
n0 together in a very small volume
o the higher the NBE per nucleon, the more stable
the nucleus
o mass defect – some mass of p+ and n0 that is
converted into energy
Computation of NBE per nucleon
1. Determine the number of protons and neutrons
I-127 has 53 protons and 74 neutrons.
2. Get the total mass of free nucleons
4. Calculate the energy in J/mol.
3. Calculate the mass defect in kg.
5. Calculate the NBE per nucleon
RADIOACTIVITY
o Antoine Henry Becquerel – first person to
discover radioactivity
o Radioactivity involves spontaneous emission of
particles by unstable nuclei.
o Unstable nuclei – radionuclides that tends to
decay into a more stable different nuclide.
Types of Radioactive Decay
o Alpha Emission – emission of an α-particle
o Beta Emission – emission of a β-particle
o Positron Emission – emission of a positron
o Electron Capture – addition of electron to a
proton in the nucleus
o Gamma Emission – emission of γ-ray
o Nuclear Stability – neutrons play a key role
stabilizing the nucleus, so the ration of proton and
neutron is an important factor.
o Nuclear Fission – splitting of a nucleus into
smaller part. It is induced by bombarding a nuclide
with a n, e, or other sub-atomic particles.
o Nuclear Fusion – two or more elements fuse
together to form one larger element
NUCLEAR POWER PLANT
harnessing energy from fission reaction for power generation.
o Commonly used isotopes:
235
U (Uranium-235), from Uranium ore
233
U (Uranium-233)
239
Pu (Plutonium-239)
o Uranium-235 Fission
235U
+ neutron ⟶ fission products + energy + 2.43 neutrons
o Uranium-238 Fission - do not split on
absorbing a neutron, but undergoes spontaneous
decay to yield fissile isotopes
o Thorium-232 Fission
Uranium Ore
o Primary raw material
o 99.27% 238U, 0.72% 235U
Process of nuclear fuel fabrication (Uranium ore)
1. Mining – physical mining
Product: uranium ore (2 kg U3O8 per ton)
2. Milling – extraction
Product: yellow cake or
impure triuranyloctoxide (U3O8)
3. Refining and Conversion – further processing of
yellow cake from the mill to remove impurities
Product: Uranium hexafluoride or
Hex (UO3, UF6)
4. Isotope Enrichment – increase concentration by
gas diffusion, gas centrifugation or molecular laser
isotope separation
Product: Enriched 235UF6
5. Fuel Fabrication – ammonium diuranate process
Product: Uranium dioxide (UO2) powder (U)
Parts of Nuclear Power Plant
o Nuclear Reactor - Devices that contain
fissionable material in sufficient quantity.
Arranged to be capable of maintaining a
controlled, self-sustaining nuclear fission chain
reaction.
▪ Burners – commonly use 235U and some type
of moderator, which slows down neutrons
to maintain the chain reaction (e.g., helium
or water)
▪ Breeders – designed to produce more fuel
than being consumed and can run w/o
moderators
▪ Converters – use 238U to produce 239Pu and
not designed to produce heat, but mostly for
military production units
o Control rods – contains neutron absorbers (e.g.,
boron, cadmium)
o Steam generators – use to convert water into
steam from heat produced in a nuclear reactor
core
o Steam Turbine – mechanical device that
extracts thermal energy from pressurized steam,
and converts it into useful mechanical energy
o Coolant Pump – pressurizes the coolant to
pressures of the order of 155 bar.
o Condenser – use to condense vapor into liquid
o Feed Pump – recirculates the condensed steam
for the next cycle of operation
o Cooling Tower – heat removal devices used to
transfer process waste heat to the atmosphere.
Water circulating through the condenser is taken
to the cooling tower for cooling and reuse.
3. FOSSIL FUELS
FOSSIL FUELS
It is a general term for buried combustible geologic deposits of organic materials formed from decayed plants
and animals by exposure to heat and pressure in the earth’s crust.
o Ancient marine bodies first turn into kerogen
(complex waxy mixture of hydrocarbon
compounds that is the primary organic
component of oil shale) before becoming a fossil
fuel.
o Kerogen + pressure and heat ⟶ Fossil fuel
Types of Fossil Fuels
o Coal – solid fossil fuel formed over millions of
years by decay of land vegetation. Most abundant
type of fossil fuels.
o Natural gas – gaseous fossil fuel that is versatile
and relatively clean compared to coal and oil. It is
mainly consisted of methane (CH4)
▪ Components:
energy components – ethane, propane,
butane, isobutane, and pentane
non-energy components – carbon dioxide,
nitrogen, hydrogen sulfate, and water
▪ Wet Natural Gas – contains hydrocarbons
in addition to methane
▪ Dry Natural Gas – gases other than
methane are removed
o Oil – liquid fossil fuel formed from the remains
of marine microorganisms deposited on the sea
floor. It is the most widely used fossil fuel.
o Sapropel (plankton, mud, anaerobic bacteria) is
converted into kerogen through anaerobic
bacteria and chemical process
Carbon Content of Fossil Fuels
o Energy gained from burning fossil fuels is
converted to electricity and heat in commercial
power plants.
o When fossil fuels are burned, carbon and
hydrogen react with oxygen in air to carbon
dioxide (CO2) and water (H2O)
o Exothermic Process - Combustion
o Electricity is generated from mechanical energy
(heat) in a turbine or generator.
PETROLEUM CONSTITUENTS
Petra = rock ; oleum = oil (crude oil)
o Crude petroleum is made up of thousands of
different chemicals including gases, liquids and
solids, ranging from methane to asphalt. It is
useless in its natural state
o Crude Oil - dark and sticky liquid
o Condensate - clear and volatile; evaporates easily
o Bitumen - semi-solid form petroleum
o Asphalt - solid form
o Hydrocarbons - makes up most of the
constituents, but there are compounds containing
nitrogen (0 to 0.5%), sulfur(0 to 6%), and oxygen
(0 to 3.5%).
high anti-knock properties = better performance of internal combustion engines
1. Aliphatic (Open chain hydrocarbons)
2. Ring Compounds
3. Lesser Components
o Sulfur (0 6%) – useless and undesirable, has bad odor and can cause corrosion in pipes
o Nitrogen (0-0.5%), Oxygen (0-3.5%), trace metals, salts
4. Natural Gas Liquids
o part of underground reservoir
o major feedstock of petrochemicals
PETROLEUM FRACTIONS
Fuel Gas/Natural Gas - Composed of hydrocarbons (such as methane, ethane, or propane), hydrogen, carbon
monoxide, oil vapors and other mixtures
1. Liquefied Petroleum Gas (LPG)
– obtained from natural gas and from the
fractional distillation of petroleum. It can be
propane or butane, a flammable mixtures of
hydrocarbon gases.
2. Gasoline/Petrol
o mixture of paraffins (alkane), cycloalkanes
(naphthene), and olefins (alkene).
o Gasoline is primarily a mixture of two
volatile liquids, n-heptane and iso-octane.
o Other chemicals are also added to gasoline
to further stabilize it and improve its color
and smell.
o Gasoline has an octane rating which
compares the gasoline blend with the
performance of pure octane hydrocarbon
with eight carbon atoms.
o The octane rating is a measure of the
resistance of gasoline and other fuels to
detonation (engine knocking) in spark
ignition internal combustion engines.
o Knocking is caused by rapid combustion. It
is a sharp metallic noise cause by high
frequency pressure oscillations inside the
cylinder.
o Anti-Knock Agent is a chemical that raises
the octane value of a gasoline, making it
more efficient (e.g., tetraethyl lead and tetra
methyl lead (TEL/TML), benzole, methyl
tertiary butyl ether (MTBE)
o minimum octane rating is 87% iso-octane
and 13% n-heptane
3. Diesel Fuel
o composed of about 75% saturated
hydrocarbons (primarily paraffins including
n-, iso-, and cycloparaffins), and
25% aromatic hydrocarbons (including
naphthenes and alkylbenzenes)
o fuel detonation takes place without spark
o has a cetane (n-C16H34) number limit
which describes the ignition quality of the
fuel
o cetane number is the measure of a fuel’s
delay of ignition time (48-50 to operate well)
o minimum cetane rating is 40% n-hexadecane
and 60% 1-methylapthalene
4. Kerosene
o a thin, clear liquid formed from
hydrocarbons, with density of 0.780.81g/cm3.
o obtained between 150°C and 275°C,
resulting in a mixture of carbon chains
containing 12 to 15 carbon atoms
5. Residues
o constituents that are not volatile enough
after distillation
o Asphalt - road paving material,
waterproofing structures, roofing material
BIOFUELS
It is produced from living organisms or from metabolic by products (organic or food waste products)
and contains over 80% renewable materials.
Types of Biofuels
1. Wood
2. Liquid Biofuel
o Ethyl alcohol - produced from fermenting
starch or sugar
o Biodiesel - made primarily from oily plants
(such as the soybean or oil palm) and to a
lesser extent from other oily sources (such as
waste cooking fat from restaurant deepfrying).
3. Biogas
o includes methane gas and other gases which
can be derived from the decomposition of
biomass in the absence of oxygen—and
methanol, butanol, and dimethyl ether—
which are in development.
Promise of Biofuels
o in combination with carbon capture and
storage, the process of producing and using
biofuels may be capable of removing carbon
dioxide from the atmosphere
o biofuel crops would remove carbon dioxide
from the air as they grow, and energy facilities
would capture the carbon dioxide given off as
biofuels are burned to generate power
o captured carbon dioxide could be sequestered
(stored) in long term repositories such as
geologic formations beneath the land, in
sediments of the deep ocean, or conceivably as
solids such as carbonates