Fact Checked

What is Volatile Matter?

M. McGee
M. McGee

Volatile matter is any substance that has a tendency to vaporize given the right conditions. A substance’s volatility is measured by its vapor pressure, the point at which a substance turns from a solid to a gas, or vice versa. Unlike temperature-based measurements, like boiling point, vapor pressure is not directly related to heat or cold and instead relies on the pressure placed on a substance. While both vapor pressure and volatile matter are common in many form physics and chemistry, one of its main industrial uses is in determining the properties of coal.

Vapor pressure is the main determination of the volatility of matter. A substance with a high vapor pressure will vaporize easily while one with a low one requires a lot more energy. In this case, the high or low designation refers to how easily the substance will become vapor.

Volatility is measured by vapor pressure.
Volatility is measured by vapor pressure.

When applied to a material, the vapor pressure determines its volatility. This often comes up when discussing flammability, since a volatile substance has a tendency to be more flammable than a non-volatile one. For this reason, it is important to study the volatility in a fuel source to determine its overall usefulness.

The volatile matter test for coal is generally a very strict operation. Different regions have their own methods, but they all involve heating a specific amount of coal to a specific temperature for a specific amount of time. This test is typically performed in a vacuum, and studies the amount and type of gasses given off by the piece of coal.

Volatile matter tests are conduced on coal, heating the coal in order to determine the amount and type of gasses produced.
Volatile matter tests are conduced on coal, heating the coal in order to determine the amount and type of gasses produced.

The analyzing of these gasses is one of the major ways people determine the best uses for coal from different areas. Some types have higher concentrations of certain materials, and that allows that particular coal to perform better in certain ways. For instance, lignite has a very high-volatile matter content along with high moisture. The moisture and volatility analysis shows that it burns for a long time with a low heat and a lot of smoke.

A volatile organic compound (VOC) is a specific type of matter that originates from the life cycle or processing of organic materials. These compounds are literally everywhere, as materials are diverse as propane fumes and the smells from flowers fall into this category. This category of substances often has a very high volatility, resulting in the ability it smell them when they are nearby. VOCs are a major source of allergens and respiratory health risks.

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Discussion Comments


The volatility of the gas didn't change, the solution did. As the gas sat unused it took on more inert liquids, likely almost entirely water. Since non-volatile liquid doesn't burn, it takes an ever increasing amount of energy to light the gas. Eventually it is out of the range of standard ignition sources.


@allenJo - That's interesting. I never thought of that before.

I think it should be pointed out that even substances which would normally be classified as volatile matter can go dormant.

Take gasoline for instance. I have some old gasoline in my garage from my lawn mower. I try to empty my lawn mower gas by the time the last mow of the season rolls around, but that’s not always possible.

I never know where to take the excess gas because the recycling facility doesn’t want it, and I’m certainly not going to spill it on the ground. So I keep it in a jar. Is that good or bad? I don’t know.

But I can tell you this – after awhile, it doesn’t ignite anymore. It’s completely dormant. I know because my wife’s car ran out of gas once, and I tried to use the old gas to bail her out, but it didn’t work. There was no ignition.


It might surprise you to learn that some volatile organic compounds live in your mouth. They are the source of bad breath and they are organic, just like the name says.

No, they won’t ignite into a flame (at least I hope not), but these bacteria do change and decay, and the process gives off that wonderful sulfuric smell that people around you will detect.

You can beat them, however, with oxygen based mouthwashes which create an aerobic environment that these bacteria cannot dwell in. I use one such mouthwash and it helps me a lot.

I also make it a point to drink a lot of water. That’s something you should do as well to keep your mouth fresh, especially if you suffer from dry mouth.

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    • Volatility is measured by vapor pressure.
      By: Kara
      Volatility is measured by vapor pressure.
    • Volatile matter tests are conduced on coal, heating the coal in order to determine the amount and type of gasses produced.
      By: siimsepp
      Volatile matter tests are conduced on coal, heating the coal in order to determine the amount and type of gasses produced.