Is It True That Oil Evaporates?

Curiosity is a fascinating concept. It helps us think about things, which leads to fresh insights and solutions. What do you believe happens to the oil while you cook? Typically, we observe a sticky residue. Is this, however, proof that the oil has vanished?

Is it true that oil evaporates? While oil does not evaporate as quickly as water, it does have the ability to evaporate in specific cases. When maintained in the open air, volatile oils can evaporate, but fixed oils are more resistant to evaporation.

In this post, we’ll look into the topic of oil evaporation by doing experiments, analysing the results, and determining the elements that cause oil evaporation.

Oils that are both volatile and fixed

You’re probably wondering what volatile and fixed oils are and how they differ from one another. Let us first discuss the chemical meaning of oil before we respond to your questions.

Oil is a triglyceride, which is an ester made up of three fatty acids and glycerol. It is a hydrophobic chemical compound that is immiscible in water. The oil contains both carbon and hydrogen.

What are volatile oils, and what do they do?

Hydrophobic concentrated compounds generated from plant tissues are known as volatile oils. They have the ability to evaporate and cannot saponify, or be transformed into soaps, when exposed to alkalis. These oils can be made both naturally and synthetically through extraction, which is commonly done with steam.

Essential oils are another name for volatile oils. No, this moniker isn’t given to them because they’re vital to our health. Rather, they contain the essence or aroma of the plants from which they were harvested.

Volatile oils are used in aromatherapy to generate relaxation and enjoyment because they contain aromatic components. The sole disadvantage of utilising these oils is that they may cause skin irritation and allergic responses.

What are fixed oils, exactly?

Non-volatile oils generated from plant seeds and animals are known as fixed oils. Alcohol makes them insoluble, whereas lipid solvents such light petroleum, ether, chloroform, and benzene make them soluble.

When these oils react with alkalis, they can be saponified, or quickly transformed into soaps.

Evaporation is a phenomena that occurs when water evaporates.

The transfer of molecules from the surface into the gaseous phase is referred to as evaporation. The air boundary layer is the layer of air that exists immediately above the liquid.

This layer serves as a conduit between the liquid and the air. Evaporation is influenced by the features of this layer.

The rate of evaporation is controlled by the boundary layer in the case of water. In the presence of wind and heat, water evaporates more quickly.

Wind tests were conducted to see if the boundary layer influences the phenomenon of oil evaporation. Let’s take a closer look at these experiments:

Experiments with Wind

Three fuels were used in the wind experiments: ASMB (Alberta Sweet Mixed Blend crude oil), gasoline, FCC Heavy Cycle (a processed oil), and water. Water, along with three other oils, was employed in the trials since it is the only liquid among the four whose evaporation behaviour is known.

The experiment took place in one of three places: a fume hood, a controlled temperature chamber, or a countertop.

Everything was tracked, from wind and air velocity to the measurements needed to create the numerous graphs needed to reach conclusions.

Following these tests, it was discovered that when oil is exposed to wind, it has no effect on its evaporation rate.

With increasing wind speed, the rate of water evaporation accelerates. In comparison to the rapid increase in wind speed, there was no discernible increase in oil evaporation rate.

As a result, it was established that the boundary layer has no effect on oil evaporation.

The temperature and evaporation rate relationship

The results of wind experiments to determine the relationship between temperature and oil evaporation rate were funny.

The temperature was discovered to be the most important element in oil evaporation. It was discovered that as the temperature of oil rises, the rate of evaporation increases linearly.

The linear relationship between oil evaporation and temperature is explained by the equation below:

Evaporating weight percentage (Ev)=PT ln t


P stands for parameter.

Temperature (T)

t stands for time.

Why does frying oil leave a residue?

Now, you’re probably wondering why, if oil evaporates as temperature rises, it leaves a residue when heated.

During cooking, the oil is usually absorbed by the meal rather than evaporating. There is oil left in the pan when we fried meals. Even the fried component of the dish has an oily coating on it.

When oil is heated in a pan, it begins to smoke before burning.

Many people believe that the sticky residue left behind is due to evaporation, however it is actually a splatter from the cooking process. Because of the following reasons:

The oil separates before it boils.

Oil droplets are released into the air when frying.

It is a combustible substance that emits smoke.

The oil must reach its boiling point, which is quite high, in order to evaporate while cooking. Water, for example, has a boiling point of 100 degrees Celsius, but olive oil has a boiling point of 191 degrees Celsius.

So, what is a liquid’s boiling point? The temperature at which a liquid turns into vapour is known as its boiling point. Due to the presence of chemical links that hold liquids together, they boil at different temperatures.

The chemical links that hold oil together are stronger than the chemical ties that hold water together because oil has a greater boiling point than water.

As a result, turning oil into vapour necessitates a significantly greater temperature. The reason for this is because oil molecules are substantially larger than water molecules and hence have greater surface area to adhere to one another.

Pure hydrocarbon evaporation is a term used to describe the process of pure hydrocarbons evaporating

The evaporation rate of hydrocarbon molecules greater than nonane and decane has been studied in a number of experiments.

In these investigations, it was discovered that the layer of air that acts as an interface between the substance and the air has no effect on them.

In both the presence and absence of wind, the evaporation rate of hydrocarbons such as decane and hexadecane shows a minor change.

Oil’s hydrocarbon chain is often longer than nonane and decane, which is why oils do not behave like water when subjected to the phenomenon of evaporation.

Is it true that oil evaporates?

Only the volatile oils can evaporate, according to the information presented in this article. Although several elements such as scale size, area, and velocity influence the evaporation phenomenon, the temperature is the only one that is critical to the oil’s evaporation. The oil’s boiling point is always higher than 110 degrees Celsius.

We also realise that the terrible occurrences of oil spills on oceans are events that cannot be easily remedied because the oils spilt are usually fixed oils. Because these oils are resistant to evaporation, they suffocate all marine life behind thick layers of oil.

Read more: Is CO2 an Ionic or a Covalent Compound?

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.


Please enter your comment!
Please enter your name here

Read More