What Are Chemical Solvents? 

A chemical solvent can be any substance that can dissolve a solute but does not chemically react with it. A solvent is always proportionally dominant than a solute. Saturation point is achieved when any additional solute cannot anymore be dissolved. The etymology of the word solvent is the Latin word solvō, which literally means “loosen, untie, solve”.

Some examples of solute-solvent relationships:

• Air (gas-gas) – nitrogen gas is about 78% of air, making it the solvent while the other components of air such as oxygen and carbon dioxide are the solutes
• The ocean (liquid-solid) – water is the solvent while salt is the main solute. Other solutes include dissolved oxygen
• Alloys (solid-solid) – combinations of metals that are melted and mixed together are called alloys. If one is proportionally larger in amount, it is the solvent. For instance, bronze is mainly composed of copper with some percentage of tin. This makes copper the solvent while tin is the solute
• Carbonated drinks (liquid-gas) – all carbonated drinks have dissolved carbon dioxide in water
• Alcoholic drinks (liquid-liquid) – all alcoholic drinks have a specific percentage of alcohol dissolved in water. The percentage of alcohol is usually expressed in “proof” which is double the numerical value of percentage. For example, the strongest liquor that is commercially available is the Polish-made Spirytus vodka, which is 192 proof or 96% alcohol. In this case, alcohol is the solvent while the remaining 4% water is the solute.

What Are Chemical Solvents Used For?

It’s a given that water is a universal solvent and the most important solvent on earth. Without it, life would not even be possible. Water is an example of a polar solvent. The polarity or non-polarity of solvents determine what type of solutes they can dissolve. Other categories of solvents include polar solvents and dipolar aprotic solvents.

Some common uses of solvents include:

• Dry cleaning (tetrachloroethylene)
• Paint thinners (toluene, turpentine)
• Nail polish removers and glue solvents (acetone, methyl acetate, ethyl acetate)
• Spot removers (hexane, petrol ether)
• Detergents (citrus terpenes)
• Perfumes (ethanol)
• Pharmaceutical products
• Epoxies and superglues

How Are Solvents Made?

Some solvents, like water, occur naturally so they do not need to be synthesised. However, some naturally-occurring solvents like benzene, which is a nonpolar hydrocarbon solvent, need to be purified or distilled from other substances that occur in nature. Generally speaking, solvents can be produced in the following ways:

• Distillation process – aliphatic, aromatic and paraffinic solvents are extracted from crude oil in this manner
• Chemical reactions – alcohols, ketones, esters, ethers, glycol ethers and glycol ether esters are synthesised by either breaking the bonds of precursor chemicals or allowing precursor chemicals to react
• Mixed solvents – some existing solvents can be mixed with other solvents or an existing solvent is already a mixture of several solvents. For instance, gasoline is a fuel that is also used as a solvent but is composed of several hydrocarbons: 4-8% alkanes, 2-5% alkenes, 25-40% isoalkanes, 3-7% cycloalkanes, l-4% cycloalkenes, and 20-50% total aromatics (0.5-2.5% benzene)