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Acid Base
Acids are proton donors or electron acceptors. Bases are proton acceptors or electron
donors. The relative amounts of acids and bases in a solution determine the pH of the
solution, with pH = 7.0 representing a neutral solution -- one that is neither acidic
nor basic. Measurement and control of pH is part of processes ranging from farming
(soil pH affects plant health) to environmental science (many air pollutants make
rain acidic) to medicine (normal blood pH is 7.4, and even slight deviations, acidosis
or alkalosis, can be harmful). Students in the USM Chemistry programs study acid-base
equilibria, buffers (pH stabilizers), and tools for pH measurement.
Bonding
Bonding refers to the way that atoms join with each other to form molecules
(for example, hydrogen and oxygen joining to form water), and the way that
molecules bind to each other to produce more complex structures (such as
antibodies and antigens joining during the immune response to disease).
The strength of bonding varies from very weak interactions between molecules
(the attraction of water molecules for cellulose, which gives a paper towel
its absorbancy) to strong atomic attachments (bonds among carbon atoms in
diamond). Chemists must understand bonding to be able to design molecules
with desired properties, such as coatings that resist water, and drugs that
prevent antibodies from attacking our own cells, as in diseases like
diabetes and lupus.
Computation
Computational methods can be simple, like plotting how the volume of a
gas changes with changing temperatures, and then fitting a line through
the data points. The equation of that line is an example of Charles's
Law. Or computational methods can be extremely complex, taking hours
of computer time. For example, a biochemist may computationally model
the active site of an enzyme to try to determine the shape of a molecule
that could deactivate the enzyme. A medicine to kill a parasite might
be developed this way. In many courses within the USM chemistry curriculum,
students (and faculty) learn to use modern computer programs for chemical
computation.
Equilibrium
Many chemical reactions do not go to completion, but instead reach equilibrium.
In this state, a mixture of reactants and products persists because forward and
reverse reactions occur at the same rate. Chemists must understand equilibria
in order to find conditions that push reactions toward completion, giving high
yields of desired products. As an example, the understanding of equilibrium was
crucial to the discovery of a process for producing ammonia for fertilizers
(and weapons) from nitrogen in the atmosphere.
Kinetics
Kinetics is the study of the rates of chemical reactions. By determining
the factors (concentrations of reactants, temperature, pH, catalysts)
that affect the rate of a reaction, chemists gain insight into precisely
what bonds are breaking and forming as one molecule is transformed into
another. With this information to guide them, chemists can design
conditions or catalysts that will promote desired reactions and
suppress undesired ones. The catalytic converter in your car promotes
more complete combustion of exhaust gases, giving a cleaner exhaust.
Biological catalysts, better known as enzymes, provide starting points
for the engineering of more powerful and specific industrial catalysts.
USM Chemistry students study kinetics in a wide variety of contexts,
from simply timing color-change reactions to monitoring reaction rates
by spectroscopy.
Redox
In redox reactions, electrons are transferred from one chemical species
(atom, molecule, or ion) to another. A species is oxidized when it loses
electrons, and is reduced when it gains electrons. These two processes
are always paired; that is, if an atom or molecule is oxidized, then
another atom or molecule must be reduced. Many important chemical
reactions are redox reactions. The corrosion of metal surfaces, the
use of batteries, chrome plating, the burning of fossil fuels,
respiration, and photosynthesis are all examples of processes that
include redox reactions. With such a wide range of uses in the natural
world, redox reactions are heavily studied by chemists.
Separations
Separations are techniques, such as chromatography, that allow
chemists to isolate pure compounds from mixtures. In the laboratory,
separations are used to remove impurities after steps in chemical
synthesis. Separation of individual compounds from complicated
fossil fuel mixtures provides numerous household products. "Natural
products" are compounds that have been isolated from materials found
in nature, and they are of interest because they sometimes exhibit
therapeutic properties. For example, long before analgesics were
routinely synthesized, it was known that willow bark soothes minor
aches and pains. After the active ingredient, salicylic acid, was
separated from inert ingredients and identified, the study of it
and related compounds led to the discovery of aspirin. Most modern
laboratories are equipped with sophisticated instruments for
separating and identifying compounds. Students enrolled in USM's
chemistry curriculum routinely gain hands-on exposure to separations
tools.
Spectroscopy
A wine critic commenting favorably on the color of a 2001 Cabernet
Sauvignon is preforming a crude spectroscopic analysis of the wine,
because its color results from the light-absorbing properties of the
wine's many individual components. Modern instruments refine and
extend spectroscopy to cover the interaction of a wide range of
electromagnetic radiation (of which visible light is only a small
portion) with matter. As radiation is absorbed, scattered, or
emitted from matter, it provides a fingerprint of the energy
levels available to the sample. This information can be used to
identify an unknown, to investigate the structure of a molecule,
to provide an image of your brain (magnetic resonance imaging,
MRI, is an application of NMR spectroscopy), or even to determine
the composition of stars many thousands of light years distant.
It is impossible to imagine modern science without spectroscopy.
Synthesis
Almost every part of our daily lives depends on, at some level,
a compound that a scientist designed and synthesized. Research
chemists often have to balance intellectual, creative, and
economic considerations in order to design new molecules and
the methods to make them. The uses of synthetic compounds are
almost endless, including pharmaceuticals that thwart disease,
diagnostic compounds that probe cancerous tissue, catalysts
that yield ever more efficient combustion products, flavors
and food additives, cosmetics and fragrances, and thin films
that coat surfaces to produce miniature superconductors.
Several research projects in the USM Chemistry Department
include synthesis, and students participate in these projects
with faculty or as part of the laboratory curriculum.
Thermodynamics
The energy of the universe is constant. The entropy of the universe
always increases. Building on these principles, thermodynamics (from
the Greek "heat" and "power") explores such diverse phenomena as
phase changes (Does diamond spontaneously become graphite under
normal conditions?), colligative properties (Is the osmotic pressure
generated across a tree root sufficient to drive sap to the top of
the tree?), heating and refrigeration, chemical equilibria, and
electrochemistry. With the introduction of statistical methods to
chemistry, thermodynamics bridges the molecular and macroscopic
realms by relating bulk properties of matter to the populations
of molecular energy states.
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