What makes chemicals react?

This is a subject right up my alley because I’m a chemist. The reason I wanted to include it is because I believe most people distrust chemicals and assume that they’re all bad. However, chemistry is a science that has made modern life possible. Most of the things we use today involve some sort of chemical process: plastics, paint, pharmaceutical drugs, fuels, processed food, electronics, artificial fibers, automobile products, toys, construction items, tools, and minor items like perfumes, beauty products, personal products, packaging, detergents and other household items all involve chemistry as part of their manufacture.

We all are familiar with chemical reactions such at baking powder fizzing when mixed with vinegar, sodium causing a fire when mixed with water, cement hardening, natural gas and propane burning, iron rusting, vinyl paint drying, and one that most people don’t remember--soap making.

As a chemist, I was responsible for creating new chemicals from ones that could be procured from chemical supply houses like Fisher Chemical in Pittsburg, Pa. The usual procedure was to mix chemicals in a flask and heat it with stirring to cause two or more chemicals to react. For example, an esterification reaction between a carboxylic acid and an alcohol to produce an ester works because a molecule of water is torn away from the two reactants by means of a dehydrating agent like sulfuric acid and results in the two chemicals being linking together to form an ester. A good example is mixing acetic acid (vinegar) and ethyl alcohol (booze) with sulfuric acid (battery acid). One ends up with ethyl acetate (used as a solvent in nail polish).

Some reactions to make plastics, which are considered polymers, involve polymerizing monomers. For example, styrene monomer (phenyethylene) will polymerize (form a long chain structure) with heating to form polystyrene, one of the most common plastics used in toys, containers, CD cases and many other inexpensive products. Plastics are considered polymers and they have interesting properties that make them useful, such as flexibility, strength, and the ability to be molded into just about any shape.

Reactions can be caused by electrolysis (using electrodes with opposite charges to produce a current). For example, water can be decomposed by electrolysis into hydrogen and oxygen gases. Combustion of these two gases is what makes water.

We all know about acid-base reactions. If one takes acetic acid (vinegar) and mixes it with sodium hydroxide (caustic) one gets a whole lot of heat and sodium acetate.

These are only a few examples of possible chemical processes. The real question to ask is: why do chemicals react?

Firs of all, one has to define what react means. A chemical reaction is defined as a change in chemical structure when two or more chemicals are mixed together. The only way that a chemical structure can change is if its bonds are broken and rearranged.

A bond is the connection between two atoms. It’s what makes compounds possible. Water, for example, consists of one oxygen atom bonded to two hydrogen atoms. The bonds between the oxygen atom and the hydrogen atoms means that they share electrons in a chemical marriage, in this case a polygamist arrangement. In most cases, the end product of a chemical reaction is when the chemical that results from the reaction has more stable bonds. In other words, the reaction results in the chemicals being driven to a more stable state. This is a thermodynamic property of molecules, which means that chemicals like to be in a stable relationship just like people.

That’s not to say that a chemical reaction cannot be reversed. Most can, but only at the cost of a lot of energy. As a matter of fact, many chemical reactions reach what is called equilibrium in which a steady state is acquired where the reaction’s forward rate is the same rate as the reaction’s reverse rate. The idea in synthetic chemistry is to drive the reaction forward by upsetting the equilibrium. This is often achieved by removing the desired product from the reaction mixture by some method such as distillation in which the product is vaporized and then condensed to be collected as a liquid. Another method is to force precipitation of the main product.

So the answer to the main question of what makes chemicals react is that everything wants to be at a lower energy state, and chemicals are no exception. A mixture of chemicals often tries to reach a more stable state, especially when forced with heat or light. Chemists spend lots of effort to achieve this state of chemical bliss.

Thanks for reading.