Main Difference – Ethanol vs Gasoline
Fuel is a source of energy. The burning of fuel produces energy. Ethanol and gasoline are two types of fuel mostly used in vehicles. The main difference between Ethanol and Gasoline is that Ethanol is composed of only ethyl alcohol molecules whereas Gasoline is composed of several types of organic molecules.
Key Areas Covered
1. What is Ethanol
– Definition, Chemical Structure, Properties, Source
2. What is Gasoline
– Definition, Composition, Properties
3. What is the difference Between Ethanol and Gasoline
– Comparison of Key Differences
Key Terms: C2H5OH, Chemical Formula, Combustion, Crude Oil, Ethanol, Ethyl Alcohol, Fuel, Gasoline, 
What is Ethanol
Ethanol is ethyl alcohol that can be used as a fuel for the production of energy. The chemical formula of ethanol is C2H5OH. The atomic arrangement of ethanol (ethyl alcohol) is given below.
Figure 1: Chemical Structure of Ethyl Alcohol
Combustion of ethanol is easy because it is a flammable compound. This combustion occurs in the presence of molecular oxygen (O2). The liquid form of ethanol is not a good fuel since oxygen cannot enter the liquid due to the tight packing of molecules caused by their strong hydrogen bonding. Therefore, ethanol should be aerosolized before burning in order to obtain a full combustion. The reaction for the combustion of ethanol is given below.
C2H5OH + 3O2 → 2CO2 + 3H2O + heat
Ehtanol is useful as a fuel because of its highly flammable property and the ease of transporting. The main source of ethanol is corn. Other plant materials containing glucose such as sugarcane also can be used for this purpose.
Ethanol has 1.5 gasoline gallon equivalency. That means, in order to replace a gallon of gasoline, 1.5 gallons of ethanol is required. This indicates that the amount of energy produced from a unit of ethanol is less than that of gasoline.
Ethanol can be produced from biomass. In addition, Ethanol can also be produced through ethylene hydration in industrial scale. Here, the ethylene molecule is hydrated from H2O in the presence of suitable conditions of temperature and pressure along with catalysts.
What is Gasoline
Gasoline is a complex mixture of several types of hydrocarbons and is used as a fuel that produces energy. Gasoline may contain up to 500 types of hydrocarbons. Gasoline is mainly made of linear chain hydrocarbon compounds. But there are also aromatic hydrocarbons present in gasoline.
The major source of gasoline is crude oil. The production of gasoline is done in petroleum refineries. The method of the production is fractional distillation. Commercially available gasoline is added with several additives in order to enhance its properties. After this mixing, the mixture is called a gasoline blend.
Figure 2: A Crude Oil Refinery
Composition
The typical composition of gasoline can be given as below.
- Aliphatic linear structures such as heptane
- Aliphatic branched structures such as isooctane
- Aliphatic cyclic structures such as cyclopentane
- Aromatic structures such as ethyl benzene
Among these fractions, the highest percentage comes from aliphatic structures rather than aromatic hydrocarbons. However, the presence of benzene cause gasoline to be carcinogenic.
Gasoline additives include olefins, diolefins, antioxidants, detergents and metal deactivators. Antioxidants are added to prevent gasoline from auto-oxidation. Phenylenediamines are the most common antioxidants that are used. Metal deactivators are added to avoid the oxidative degradation of gasoline by metal ions. Detergents are used to minimize the deposits of the suspended particles.
Difference Between Ethanol and Gasoline
Definition
Ethanol: Ethanol is a fuel composed of ethyl alcohol molecules.
Gasoline: Gasoline is a fuel composed of different types of hydrocarbons.
Composition
Ethanol: Ethanol is composed of alcohol molecules (ethyl alcohol).
Gasoline: Gasoline is composed of about 500 hydrocarbons such as heptane, ethyl benzene, etc.
Energy Production
Ethanol: A gallon of Ethanol produces a less amount of energy than gasoline.
Gasoline: A gallon of Gasoline produces one-third more energy than Ethanol.
Sources
Ethanol: Ethanol is mainly produced from biomass of corn and sugarcane.
Gasoline: Gasoline is produced from crude oil.
Effects on Environment
Ethanol: Ethanol is more environmentally friendly due to its complete combustion.
Gasoline: Gasoline is less environmentally friendly due to its incomplete combustion that produces carbon and carbon monoxide.
Damage to Engines
Ethanol: Ethanol can cause damages to the engine.
Gasoline: Gasoline does not cause damages to the engine.
Conclusion
The main difference between ethanol and gasoline is in their composition and their subsequent properties. Although ethanol is more environmental friendly than gasoline, ethanol is not 100% environmental friendly. That is because the combustion of ethanol forms carbon dioxide which is released into the environment. This release cause O2-CO2 imbalance of the atmosphere.
References
1. “Ethanol as a Fuel.” EasyChem – The Best HSC Chemistry Notes, Syllabus Dot-Points, Past Papers and Videos. N.p., n.d. Web. Available here. 03 July 2017.
2. “Engine & fuel engineering FAQ.” Engineering forums for professionals. N.p., n.d. Web. Available here. 03 July 2017.
3. “Biofuel Chemistry: How they Burn?” Biofuel.org.uk. N.p., n.d. Web. Available here. 03 July 2017.
Image Courtesy:
1. “Ethanol-3d-stick-structure” By Keenan Pepper at English Wikipedia -(Public Domain) via Commons Wikimedia
2. “Anacortes Refinery 31911” By MS Turmel, University of Manitoba, Plant Science Department (Public Domain) via Commons Wikimedia
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