Human Eye – Image: Stock Photo Exchange

Fossil fuels are still the most common source of home heating. These include natural gas and propane gas. Where piped natural gas is unavailable, propane is often the heating fuel of choice. Are you heating with propane gas? If so, you may experience certain difficulties.

Use any Internet search engine and you will find those who complain their gas heater produces fumes that burn their eyes, leading to blurry vision. Although among burners of propane gas, there will be some that complain of “dry-eyes,” in actuality, its combustion actually releases considerable moisture.

What are those fumes—in other words—what is the chemistry behind the combustion of propane gas? Consider the stoichiometric equation that scientists write for the burning of propane gas in the presence of oxygen.

CH₃—CH₂—CH₃ + 5 O₂ → 3 CO₂ ↑ + 4 H₂O ↑

We read: one molecule of propane gas plus five molecules of oxygen gas yields three molecules of carbon dioxide that enter the atmosphere, along with four molecules of water vapor, that do the same.

Now, although small quantities of carbon dioxide and water are found in our atmosphere, consider what water and carbon dioxide can produce if they exist in abundance:

H₂O + CO₂ → H₂CO₃

The above clearly demonstrates that one molecule of water plus one molecule of carbon dioxide gas yields one molecule of carbonic acid, H₂CO₃. Although carbonic acid is not a particularly strong acid, it is still capable of burning the eyes. Why, the burning feeling one gets from chopping onions is due to the presence of an acid.

So if you decide you intend heating with propane, be forewarned of the possible/probable difficulties you can experience.

What Can Be Done?

Other than changing the fuel used to heat the home, one thing that may reduce the problem is spending as little time as possible in the room that houses the heater. Alternatively, or in conjunction with this, one could heat the room, turn the heater off, and then occupy the room some little time afterward.

Resources: personal experience plus a knowledge of basic organic chemistry.
Originally published by Vincent Summers on April 17, 2012 on Quirky Science under the title, Do You Heat with Propane? Do Your Eyes Burn?