The key difference between gasoline and diesel is that the diesel is less volatile and has a higher boiling point than the gasoline.
Gasoline and diesel are two major types of fuel that we often use in vehicles. However, they are two different mixtures of hydrocarbon compounds. The major reason for the above difference between gasoline and diesel is that diesel consisting of hydrocarbons, which have more carbon numbers than gasoline. Therefore, the molecular weight of diesel is higher than gasoline.
What is Gasoline?
Gasoline is a mixture of a large number of hydrocarbons, which have 5-12 carbons. There are aliphatic alkanes like heptane, branched alkanes like isooctane, aliphatic cyclic compounds, and small aromatic compounds. But there are no alkenes or alkynes other than these hydrocarbons.
Gasoline is a natural by-product of the petroleum industry, and it is a nonrenewable source. Moreover, it is produced in the fractional distillation of crude oil. When we separate the crude oil based on the boiling points of different compounds, the low molecular weighted compounds in the gasoline collects in the same range. In some countries, gasoline has the name “petrol”, and it is a fuel that we use in internal-combustion engines of vehicles. The combustion of gasoline produces a high amount of heat energy and carbon dioxide and water.
Further, manufacturers mix additional compounds with gasoline in order to enhance its use in engines. There, we can add hydrocarbons like isooctane or benzene and toluene, to increase its octane rating. This octane number measures the ability of an engine to cause self-ignition in the engine cylinders (which causes knocking). When this fuel mixes with air in premature ignition, before the spark passes from the spark plug, it pushes against the crankshaft producing a knocking sound. Due to this knocking, the engine tends to overheat and lose power. Therefore, it damages the engine in the long run.
In order to reduce the knocking effect, we need to increase the octane number of the fuel. Other than adding hydrocarbons, we can increase the octane number also by adding certain lead compounds. This will increase the octane number; thus, gasoline becomes more resistant to the self-ignition which causes knocking. The prices of this fuel are largely varying over time with the price of crude oil. Since gasoline has become a primary need, in most of the countries, the variation in oil prices affects the country’s economy too.
What is Diesel?
Diesel is an automobile fuel which is a by-product of petroleum distillation. It is an oil-like, denser fuel and it has a higher boiling point than water. It consists of hydrocarbons having longer carbon chains where they have carbons from 8 to 21. The compounds in this fuel include paraffin, isoparaffins, naphthenes, olefins and aromatic hydrocarbons. Depending on the usage, we can categorize it into different grades. Such as 1-D (S15), 1-D (S500), 1-D (S5000), 2-D (S15), 2-D (S500), 2-D (S5000) and 4-D.
The Cetane number of diesel is a property for end users to look at. It measures the ignition quality of the fuel. Cetane number is different from the octane number of gasoline. For instance, the higher the cetane rate, the more easily it ignites. Although the combustion of diesel results in low amounts of carbon monoxide, carbon dioxide, they give out high amounts of nitrogen compounds and particulate matter, are responsible for acid rain.
What is the Difference Between Gasoline and Diesel?
Gasoline is a mixture of a large number of hydrocarbons, which have 5-12 carbons and diesel is an automobile fuel which is a by-product of petroleum distillation. The key difference between gasoline and diesel is that diesel is less volatile and has a higher boiling point than gasoline. Moreover, diesel is oily like and smells differently than gasoline. As another important difference between gasoline and diesel, gasoline can be rated according to the octane number, whereas diesel is rated according to the cetane number. Apart from that, diesel is cheaper than gasoline, but gasoline is cleaner and more environmentally friendly.
The below illustration provides more information on the difference between gasoline and diesel.
Summary – Gasoline vs Diesel
Gasoline and diesel are two types of fuels that we often use in vehicles. Both of the fuels have pros and cons of using it. In terms of environmental safety, both are harmful. The key difference between gasoline and diesel is that diesel is less volatile and has a higher boiling point than gasoline.
1. Gable, Christine & Scott. “What You Should Know About the Diesel Fuel Cetane.” ThoughtCo, Jun. 22, 2018. Available here