Difference Between Propane and Propene

Main Difference – Propane vs Propene

Hydrocarbons are compounds made out of only C and H atoms. Propane and propene are hydrocarbon compounds. These compounds are obtained from petroleum oil wells at petroleum oil processing plants. Both these compounds can be used as LP gas since they can be liquefied easily. Propane and propene are gases at room temperature due to the low boiling point. These are flammable compounds. The main difference between propane and propene is that propane is an alkane having only single bonds whereas propene is an alkene having a double bond apart from single bonds.

Key Areas Covered

1. What is Propane
      – Definition, Chemical and Physical Properties
2. What is Propene
      – Definition, Chemical and Physical Properties
3. What are the Similarities Between Propane and Propene
      – Outline of Common Features
4. What is the Difference Between Propane and Propene
      – Comparison of Key Differences

Key Terms: Alkane, Alkene, Combustion, Double Bond, Flammable, Hydrocarbons, LP Gas, Petroleum Oil, Propane, Propene, Single Bond, Unsaturation

What is Propane

Propane is an organic compound having the chemical formula C₃H₈. It is an alkane whose chemical bonds are single bonds (propane is a saturated compound). It is a colorless gaseous compound that can easily be liquefied. Therefore, the most common application of propane is its use as LP gas (liquefied petroleum gas). The molecular mass of propane is 44.10 g/mol.

Figure 1: Chemical Structure of Propane

Propane can be obtained naturally in petroleum chemical mixtures. Therefore, the manufacturing process for propane includes the separation and collection of the gas from its source. Here, crude oil and natural gases are pumped out from the deep locations on earth. Generally, natural gas is composed of methane 90%, propane 5%, and other compounds. Propane gas can be separated from the natural gas mixture at a processing plant.

The boiling point of propane is around -42^oC. Therefore, liquid propane can easily be vaporized due to its very low boiling point. When LP gas is used as soon as the lid of the container is opened, liquid propane will be converted into propane gas that can be burnt to get energy.

Propane is heavier than normal air since the relative density of propane is higher than 1. Therefore, if there is a mixture of propane and normal air in the same container, propane gas will sink to the bottom of the container.

The major chemical reaction that propane undergoes is combustion reaction. Propane can undergo either complete combustion or incomplete combustion. The complete combustion of propane produces carbon dioxide, water vapor, and heat energy. But when there isn’t sufficient oxygen, incomplete combustion will take place, forming carbon monoxide along with carbon dioxide, carbon soot, and water vapor. The complete combustion produces more energy.

What is Propene

Propene is an organic compound having the chemical formula C₃H₆. The molecular weight of propene is about 42.081 g/mol. It is a colorless gas at room temperature. It has a petroleum-like odor. This compound is composed of C and H atoms that are bonded to each other via single bonds and there is a double bond between two carbon atoms. Hence propene is an unsaturated compound.

Figure 2: Chemical Structure of Propene

Propene is an alkyne. It is composed of sigma bonds and a pi bond. It has a linear chemical structure. Due to its unsaturation, propene is very important in producing polymer compounds. The double bond can undergo addition polymerization by opening up the double bond. The polymer made out of propene is poly(propene) (common name is polypropylene).

The major chemical reaction propene undergoes is combustion. It can be either complete combustion or incomplete combustion. The combustion reactions are similar to that of propane. The boiling point of propane is about −47.6 °C. Propene also can be liquefied. Due to the low boiling point, it quickly converts into the gas phase. Propene vapor is heavier than air.

Similarities Between Propane and Propene

Both are hydrocarbon compounds.
Both are gases at room temperature.
Both can be used as LP gas.
Both are flammable gases.
Both form the same end products via complete combustion and incomplete combustion.
Both gases are heavier than air.

Definition

Propane: Propane is an organic compound having the chemical formula C₃H₈.

Propene: Propene is an organic compound having the chemical formula C₃H₆.

Number of Hydrogen Atoms

Propane: Propane is composed of 8 hydrogen atoms.

Propene: Propene is composed of 6 hydrogen atoms.

Molecular Mass

Propane: The molar mass of propane is about 44.10 g/mol.

Propene: The molar mass of propene is about 42.081 g/mol.

Boiling Point

Propane: The boiling point of propane is -42^oC.

Propene: The boiling point of propene is -47.6 ^oC.

Chemical Bonding

Propane: Propane has only single bonds.

Propene: Propene has single bonds and a double bond as well.

Conclusion

Propane and propene are hydrocarbon compounds composed of C and H atoms. Propane is an alkane that has no double bonds in its structure. Hence, it is a saturated compound. Propene is composed of a double bond in its structure. Therefore it is an unsaturated compound. This is the main difference between propane and propene.

References:

1. “Propane.” How Products Are Made, Available here.
2. “Propane.” Encyclopædia Britannica, Encyclopædia Britannica, inc., 14 July 2017, Available here.
3. Lazonby, John. “Propene (Propylene).” The Essential Chemical Industry online, Available here.

Image Courtesy:

1. “Propane-2D-flat” By Holger87 – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Propene-2D-flat” By Nothingserious – Own work (Public Domain) via Commons Wikimedia