Ethanol’s Combustion Equation – What Happens When Ethanol is Burned?

Ethanol’s combustion equation represents the sequence of exothermic chemical reactions that occur between a fuel and an oxidant when it is exposed to heat. In simpler terms, combustion is known as the burning of fuel, which then results in either a glow or a flame.

What is Combustion?

Combustion refers to the act of burning a fuel. It can be either complete or incomplete. In a complete combustion, the reactant burns due to the presence of oxygen, and this produces a limited number of products depending on the reactant.

For example, if the reactant is a hydrocarbon, it will produce carbon dioxide and water when it is burned in oxygen. If carbon is burned, it will yield carbon dioxide, whereas if nitrogen is burned, it will yield nitrogen dioxide. In an incomplete combustion, there is not enough oxygen to cause a complete reaction so the end products are usually not produced. Incomplete combustion will yield different products. For example, if carbon experiences incomplete combustion, it will produce toxic carbon monoxide instead of carbon dioxide.

Combustion of Ethanol

In the case of ethanol, when it is burned and experiences complete combustion, it will produce carbon dioxide and water due to the presence of a carbon chain and an OH group in the ethanol structure. However, if ethanol undergoes incomplete combustion, the result is potentially harmful as it will yield acetaldehyde instead.

In a complete combustion, the ethanol combustion formula is C2H5OH(l) + 3 O2(g) =Heat=> 2 CO2(g) + 3 H2O(g).

This equation shows that when ethanol (C2H5OH) is exposed to heat, there will be an exothermic reaction that causes the ethanol to break apart. The carbon content combines in air, and so does the hydrogen. Thus, as can be seen in ethanol’s combustion equation, the end products of an ethanol combustion reaction are CO2 (carbon dioxide) and H2O (water), both in vapor form.

Ethanol Combustion and Your Car

The combustion of ethanol is what enables it to be converted into energy so it can run vehicles. The combustion formula of ethanol offers a peek of one of the reasons why using ethanol is great for your car, your health, and for the environment. Ethanol’s combustion equation shows that when ethanol is burned by an engine, it will produce only carbon dioxide and water, which are harmless to the environment. This is in contrast to gasoline, which, when burned, produces nitrogen, carbon monoxide, and a lot of ozone pollutants.

However, since not all cars these days can run on pure ethanol or on E85, which is made up of 85% ethanol and 15% gasoline, the more conventional E10 blend is more widely used. This means that the resulting mixture will still provide potentially harmful ingredients into the air.