A percentage of alcohol in gasoline is also one of the necessary mixtures. This mixture is responsible for modifying the compound, changing its price and interfering with its efficiency. Do you want to know more about this mixture, how it is made and why the changes occur? In this article, we will explain all these details.

Why is alcohol added to gasoline?
It is a law

First, it is important to emphasize that the addition of a percentage of alcohol to gasoline is determined by law. Since 1993, Law No. 8,723 stipulates the need to mix anhydrous alcohol in gasoline, and the percentage (which started at 22%) has been changing over the years.

Better efficiency

Among other reasons, the addition of alcohol to gasoline – in the proportions in which it occurs – works as an anti-knock agent, that is, a substance capable of slowing down the combustion of gasoline, increasing its efficiency. What happens is that alcohol, due to its lower calorific capacity, increases the octane rating of gasoline, making it resistant to greater compression, and consequently improving performance. (Read more about octane rating by clicking here).

Sustainability

In addition to increasing the octane rating, the addition of anhydrous alcohol makes emissions from burning gasoline less polluting, since the release of carbon monoxide (CO) is reduced. The other emissions from ethanol are also not a problem, since the CO2 released is used for the photosynthesis of sugarcane, which will produce more of this compound.

Independence

Another reason why the addition of a percentage of alcohol to gasoline began in Brazil was the idea of ​​reducing dependence on foreign oil, given that Brazil is a major producer of ethanol due to the abundance of sugarcane production in the country.

Therefore, it is easy to see that there are many reasons for adding a percentage of alcohol to gasoline, but what is the composition of the gasoline sold at gas stations?

Composition of gasoline sold

For regular and additive gasoline, the percentage of anhydrous alcohol that must be added currently (2021) is 27%. Therefore, gasoline purchased at gas stations is, in reality, a mixture of 73% gasoline with 27% anhydrous alcohol.

There is also another situation, which is the case of Premium Gasoline and Podium Gasoline, where the Ethanol mixture drops to 25%, making up 75% gasoline. In this scenario, there is no loss of fuel efficiency, since gasolines are better prepared to provide better performance to vehicle engines. (Learn more about Premium and Podium Gasolines by clicking here).

The correct percentage of this mixture is extremely important for the proper functioning of any automobile that uses gasoline as fuel, for several reasons. The first of these, in the case of adding a lower percentage of ethanol, concerns higher emissions of carbon monoxide (CO) into the atmosphere, which is more harmful to the environment.

In addition, if the percentage of alcohol in the mixture is increased to a higher than normal, the vehicle is likely to start to present failures, as it was not manufactured to work with a fuel of this composition. Except in situations where the car is flex fuel, but in this case the consumer will be losing a few kilometers of performance.

For these reasons, it is necessary for the consumer to be aware of possible adulterations in the fuel. If there is any doubt about the quality of the gasoline, below we will show how the percentage of alcohol can be quickly checked.

How to find out the percentage of alcohol in gasoline

Since ethanol, in addition to being colorless, forms a homogeneous mixture with gasoline, it is impossible to visually identify the amount of alcohol present in gasoline sold at gas stations. However, by performing a simple procedure, it is possible to find out the percentage of alcohol present in gasoline. This process serves to identify possible fraud in the fuel purchased, in case there is any suspicion. (Read more about fuel adulteration by clicking here).

The following test is called the “test tube test”. You will need the following materials:

A test tube of at least 150 ml
50 ml of gasoline
50 ml of salt water
A pair of rubber gloves

The procedure is simple. Just add the two liquid components to the test tube, regardless of the order, and then cover it with the glove and mix the liquids, turning the test tube upside down at least ten times.

From there, just let the mixture rest for about 15 minutes in a place with room temperature, and then check the result.

The mixture, which started with 50% colorless liquid (salt water) and 50% gasoline, will now be in different proportions. This is because Ethanol tends to mix more easily with saline water than with gasoline, and so the colorless liquid (saline water + ethanol) will correspond to more than 50% of the mixture.

Let’s give an example: if the colorless liquid marking, which previously represented 50ml, now represents 65ml, the amount of ethanol present in the gasoline was 15ml. Therefore, to know in terms of percentage, just do a simple rule of 3.

If 50ml of gasoline before the mixture was 100% of the fuel, 15ml represents x%. Therefore, the percentage of alcohol will be given by the following expression:

Amount of alcohol / Amount of gasoline * 100

In the case of our example, alcohol represents 30% of the mixture, which is not in accordance with the standards previously defined by law. Therefore, this fuel is adulterated.

Alcohol content by country

In Brazil, when the requirement for a certain percentage of alcohol in gasoline was defined by law, this value started at 22%. However, in other countries an alcohol content in the mixture is also required, and in most cases it is different from the Brazilian percentage.

See below a list of alcohol concentrations in gasoline in some countries around the world:

Argentina 5%
Australia 4%
Canada 5%
Chile 5%
China 10%
Colombia 10%
Costa Rica 7%
European Union 10%
India 5% to 10%
Paraguay 24%
Peru 7.8%
Philippines 10%
South Africa 10%
Uruguay 5%
Vietnam 5%

With these values, the question remains: what do you think of the percentage of alcohol required in gasoline in Brazil?

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