Is Chloroform Flammable?

In this article we will discuss the following: “Is Chloroform Flammable?”, and other important questions regarding the nature of chloroform and fire.

Is Chloroform Flammable?

No, it’s not. Chloroform is not a fire hazard. Chloroform can be burned but no flames would arise from that. Although, toxic vapors can evaporate if the substance is heated.

Introduction

Chloroform is a colorless liquid that can easily form vapors. 

If inhaled or ingested, it is a powerful anesthetic, anxiolytic, sedative, and euphoriant, but is also toxic.

Chloroform (CHCl3) can be found in nature. It’s a product of the metabolism of some algae species, and can also be produced in soil by abiotic processes. But the chloroform we use is produced industrially.

The compound is produced by heating a mixture of chlorine (Cl) with chloromethane (CH3Cl) or methane (CH4), yielding CHCl3. This chemical reaction is called halogenation (free radical halogenation).

Uses

The most widespread use for chloroform is in the production of Teflon. Chloroform reacts with hydrogen fluoride (HF) to produce monochlorodifluoromethane (CHClF3), whose molecules can react with each other to produce a non-sticking coating in pans.

Another important use of CHCl3 is as a solvent. It can dissolve hard fats, oils, rubber, waxes, and resins since it mixes well with organic compounds. It’s also a cleansing agent that can be used as a pesticide fumigant.

In the past, chloroform was used as an anesthetic. Discovered first in 1842 by an English physician named Robert Mortimer Glover, the compound started being used during surgery procedures across Europe in the same decade.

In the 1850s, a physician named John Snow used it in the birth of Queen Victoria’s last two children. The compound began to replace ether as an anesthetic in the U.S at the beginning of the 1900s. Only in the 30s, CHCl3 start being replaced by nitrous oxide.

Health hazards

Chloroform is readily absorbed by the lungs, skin, and gastrointestinal tract. It can be eliminated by the lungs unchanged or going through other metabolism paths.

The substance is considered harmful, irritant, and even carcinogenic.

Acute exposure can induce the following effects: irritation to the nose, throat, eyes, skin, and mouth; and also excitement, vomiting, nausea, dizziness, ataxia, and drowsiness. The exposure can lead to hepatic and renal damage.

According to The International Agency for Research on Cancer, chronic ingestion or inhalation may lead to hepatic damage and cancer.

Exposure to high concentrations can cause convulsions, coma, cardiac arrhythmias, and lead to death. Dermal exposure can occasion systematic toxicity, dermatitis, and burns (this last one is not due to combustion or fire).

Will chloroform catch fire?

Applying fire to CHCl3 will not lead to flares or fires. It won’t ignite and start a fire. Heating chloroform, although, may lead to thermal decomposition, and toxic vapors can rise.

Chloroform can be oxidized but it won’t happen under normal circumstances. Fire is not a problem when dealing with CHCl3, but reactivity is.

Let’s analyze the science behind chloroform to understand how everything happens.

Basic Chemistry and flammability

Everything we can weigh out is made of atoms. They are the ordinary particles that compose all that have mass. There are also smaller particles, but they are not important right now.

An atom is anything labeled in the periodic table. They are the basic building blocks of anything palpable in the universe, no matter if it’s solid, liquid or gas.

Atoms have electrons spinning around a nucleus. These electrons are the things that connect atoms with each other, creating molecules.

Atoms bond with each other, for several reasons. One of them is because they’re constantly and insatiably searching for stability. As a result, atoms bond and interact with each other when they get close, like the moon orbiting our planet, creating molecules.

Chemistry studies these bondings and what we can do with them.

Now, flammability is a characteristic of organic compounds.

Normally, we see a fire when a hydrocarbon is burning. These molecules are made entirely from hydrogen and carbon atoms, so the byproducts from burning can only be arranged between carbon, hydrogen, and oxygen since combustion is a reaction with air.

To understand how fire takes place and in which condition chloroform can burn, let’s first review a few important science concepts.

Organic compounds

Even though chloroform has a carbon atom on each molecule, it is not flammable. 

Organic compounds always have carbons within, bonded with at least one hydrogen, and two other things. In a hydrocarbon, these two other things are another carbon or hydrogen.

Hydrocarbons

As we discussed, hydrocarbons are made from carbon and hydrogen. You can look at them like they were a blueprint for the rest of the organic compounds because they are the simpler organic molecules possible.

As you can see from the picture below, there’s a certain chemical language we use to name organic compounds. Everything depends on how many carbon atoms a structure has.

If it has only one carbon on each molecule, we are talking about methane, which is a bad greenhouse gas that cows eliminate on their farts. If we take a molecule with 8 carbons we have octane, which is a major constituent of gasoline.

When we burn gasoline, it gives us a lot of energy. That’s why we use them to move our cars. If we burn chloroform, although, it won’t give us energy.

Source:https://sites.google.com/site/csetstudyguidechemistry/home/6-1c-organic-chemistry-biochemistry—ten-simplest-hydrocarbons

Now, if we take the gas from cow farts and exchange three of their hydrogens for chlorides, we are going to synthesize chloroform. Of course, chemical synthesis is far more complicated than that but, in the end, is like we simply change the ligands carbon has.

When something burns, we are talking about a reaction with the air’s oxygen. No atom ceases to exist after catching fire, they’re simply arranged differently.

When hydrocarbons burn they produce carbon dioxide (CO2) and water(H2O). This is because the oxygen in the air reacted with carbon and hydrogen. They’ve exchanged their bondings and created new ones with oxygen, to become more stable.

Chloroform

Chloroform is a molecule similar to methane. It has only one carbon, one hydrogen, and two chlorides.

Chloride itself has its own specific properties. The most important is that it has a strong affinity with electrons. It really wants to steal electrons for itself.

Chloroform structures. These four are all the same molecules, they are just drawn differently.

Source: the author

As you can see, chloroform has not only one but three chlorides, all pulling the poor carbon on each side (pulling its electrons, actually). This grants chloroform special properties, like the capacity of creating polymers.

When a chloroform molecule burns, it produces CO2 and H2O, but also others like CO, CO2, CI2, and HCI (Hydrochloric acid). Many other intermediary compounds are formed during chloroform’s thermal oxidation. 

But the temperature required to burn chloroform is around 450ºC/ 842ºF.

The intermediaries have a short life, but can be hazardous for us and react with countless other compounds that may be in the air or near where the fire is happening.

Chloroform flammability

You might be wondering: can chloroform burn, after all?

The chemical answer is: sure, just like any other organic compound.

But the real answer is: after we apply a temperature around 450ºC, chloroform will start decomposing, but no fire will come out of it because this chemical reaction is not exothermic.

We can only see a fire if the fuel gives energy after burning. That’s the whole point of burning fuels.

Conclusion

Chloroform is not a fire hazard. Even if we try to burn it, we wouldn’t get any heat from the thermal decomposition. But chloroform can unleash toxic vapors if heated, which can be hazardous to our bodies.

Frequently Asked Questions (FAQS): Is Chloroform Flammable?

is chloroform polar?

Polar molecules have unequal distribution of charge across themselves. The geometry of their molecules is distorted, and the resultant dipole moment value is different than zero.

The dielectric constant of water (which is very polar) is around 78.5, while it is 4.8 for chloroform. We can say that chloroform is slightly polar, practically nonpolar.

is chloroform toxic?

Yes. Chloroform can give off irritating and toxic fumes, especially if heated. There is sufficient evidence using animal models to support the theory that chloroform has carcinogenicity to humans.

is chloroform soluble in water?

It’s only slightly soluble in water. It’s very soluble in nonpolar substances.

Citations

Lou, J. C., & Chang, Y. S. (1997). Thermal oxidation of chloroform. Combustion and Flame, 109(1-2), 188–197. doi:10.1016/s0010-2180(96)00148-4 

https://www.cdc.gov/niosh/topics/chloroform/default.html
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/338535/Chloroform_Toxicological_Overview.pdf
https://en.wikipedia.org/wiki/Chloroform
https://en.wikipedia.org/wiki/Chloride
https://pubchem.ncbi.nlm.nih.gov/compound/6212
https://nj.gov/health/eoh/rtkweb/documents/fs/0388.pdf

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