What makes something volatile

Porrino, Ph. David P. Friedman, Ph. Leslie Morrow, Ph. Kathleen K. Sulik, Ph. Search Search. Volatility of a Liquid With sufficient kinetic energy, most liquids can become gases through the process of vaporization.

Volatile liquids have low boiling points. A liquid with a low boiling point will begin to boil faster than liquids with higher boiling points.

Much less energy in the form of heat is required to break the intermolecular bonds of a volatile liquid than those of liquids having higher boiling points. Once enough energy is supplied to break apart the bonds between molecules, the molecules are free to expand and escape the liquid surface in the form of a gas.

For example, the European Union uses the boiling point, rather than its volatility in its definition of VOCs. VOCs are sometimes categorized by the ease they will be emitted. The higher the volatility lower the boiling point , the more likely the compound will be emitted from a product or surface into the air. Very volatile organic compounds are so volatile that they are difficult to measure and are found almost entirely as gases in the air rather than in materials or on surfaces.

The least volatile compounds found in air constitute a far smaller fraction of the total present indoors while the majority will be in solids or liquids that contain them or on surfaces including dust, furnishings and building materials. In the United States, emissions of VOCs to the outdoors are regulated by EPA mostly to prevent the formation of ozone, a constituent of photochemical smog.

VOCs that are non-reactive or of negligible reactivity to form ozone under these conditions are exempted from the definition of VOCs used by EPA in its regulation. Since first establishing the list of exempt compounds in , the EPA has added several to the list, and frequently has several petitions for additional compounds undergoing review.

In addition, some states have their own definitions and lists of exempted compounds. Thus, for regulatory purposes, the specific definition of VOCs outdoors can change by what is excluded from that definition. This terminology clarified its meaning as being limited to reactive chemicals. To the extent that some exempted compounds impact the health of exposed individuals indoors, the definition of VOCs regulated for outdoor air has the potential to create serious misconceptions for indoor air quality, therefore, such VOCs should not be excluded from consideration for indoor air.

For example, methylene chloride paint stripper , and perchloroethylene dry cleaning fluid , are exempted compounds for outdoor regulation, but they could pose serious health risks to exposed individuals if present indoors.

The first is listed by the International Agency for Research on Cancer IARC as a potential human carcinogen and the second is listed as a probable human carcinogen.

Indoor VOCs react with the indoor ozone 9 even at concentrations below public health standards. The chemical reactions produce sub-micron sized particles and harmful by-products that may be associated with adverse health effects in some sensitive populations. When discussing indoor environments, all organic chemical compounds that can volatize under normal indoor atmospheric conditions of temperature and pressure are VOCs. The three classifications are all important to indoor air, and are all considered to fall within the broad definition of indoor volatile organic compounds.

Other than volatility or boiling point no other criteria are used to define VOCs indoors. Knowledge about the VOCs that are present at low concentrations normally found in indoor air.

All available measurement methods are selective in what they can measure and quantify accurately, and none are capable of measuring all VOCs that are present. For example, benzene and toluene are measured by a different method than formaldehyde and other similar compounds. The range of measurement methods and analytical instruments is large and will determine the sensitivity of the measurements as well as their selectivity or biases.

Generally speaking, high volatility is connected to a high flammability and a certain degree of danger due to the fact that there are more of these flammable fumes in the air.

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