What is Physical Chemistry?
Energy Changes, Atomic Structure and Reaction Rates
Burning fuels, refrigeration, radioactivity, enzymes and cookery all depend on processes and theories in a less glamorous branch of science.
Physical Chemistry looks at chemistry from a different angle to inorganic and organic chemistry. Whereas these branches study the reactions of different groups of elements and compounds, physical chemistry uses mathematics and physics to determine laws which describe the way chemical reaction happen.
Energy, Structure and Rate
So physical chemistry deals with Thermodynamics or the energy levels and changes involved in chemicals and chemical reactions. It also deals with the Quantum Mechanics of chemicals. This is the atomic and molecular structure of the chemicals. Finally it deals with Kinetics or the rates of reactions and how they are changed.
Obscure but Fundamental
It could be argued that this is the least interesting of the branches of chemistry. It involves lots of mathematical formulae and obscure theories involving Greek letters. Of course these concepts are also vital for many important processes in nature and in many of the equipment we take for granted.
Energy Changes
Thermodynamics involve changes in energy. Changes in heat energy cause changes in temperature, which is foundational to cooking, refrigeration and transport. Chemical reactions which produce heat are exothermic, such as in burning fuel or an exploding bomb. This usually means that chemical bonds have been broken. Chemical reactions which take heat in are called endothermic and usually mean that chemical bonds have been formed.
Atomic Structure
Quantum mechanics deals with the structure of the very foundational units of all matter, atoms. So the arrangement of atoms in different solids such as steel, concrete and ice are determined by this discipline. But this study also led to the discovery of the structure of the atomic nucleus leading to both the atomic bomb and nuclear energy.
Speed of Reaction
Kinetics is about speed of reaction. We depend on reaction rates in so many ways in our modern lives. If reactions in the body did not involve enzymes which control the rate of the reactions, we would not be able to live due to the reactions happening too slowly. The different cooking methods demonstrate the way different conditions affect the rate of reaction; to bake a potato takes hours in a conventional oven, but only a matter of minutes in a microwave oven.
Catalysts
The study of the way rates of reaction can be changed by catalysts like enzymes or precious metals such as platinum or rhodium is important. Reverse catalysts or inhibitors are important in the preservation of foodstuffs and have been greatly developed.
Collision Theory
The way conditions affect reaction rates is all about collisions. For example as temperature increases the particles move around faster and so are more likely to collide and react quicker. Higher concentration also causes more collisions. This is an important part of the study of kinetics.
Physical chemistry is a less glamorous but foundational part of scientific study.
