What is the Difference Between Pentane and Cyclopentane

The main difference between pentane and cyclopentane is that pentane is a straight-chain alkane with the molecular formula C₅H₁₂ whereas cyclopentane is a cyclic hydrocarbon with the molecular formula C₅H₁₀.

Hydrocarbons are a class of organic chemical compounds that compose only of the elements carbon and hydrogen. Pentane and cyclopentane are hydrocarbons but have different structures and properties.

Key Areas Covered

1. What is Pentane 
     – Definition, Structure, Properties 
2. What is Cyclopentane
     – Definition, Structure, Properties 
3. Similarities Between Pentane and Cyclopentane
     – Outline of Common Features
4. Difference Between Pentane and Cyclopentane
     – Comparison of Key Differences

Key Terms

Pentane, Cyclopentane

What is Pentane

Pentane is a hydrocarbon that belongs to the group of alkanes. Pentane has a chemical formula of C₅H₁₂. It is a straight-chain alkane with five carbon atoms bonded together with 12 hydrogen atoms. It is a colorless and odorless liquid. Moreover, it has a low boiling point and is highly flammable. The boiling point of pentane is 36 degrees of Celsius, whereas the melting point is -130.5 degrees Celsius. Pentane has a molar mass of 72.151 g mol^-1. It is a nonpolar molecule; this means that it does not have any prominent dipole moment. The density of pentane is 626 Kg m^-3.

Furthermore, there are many uses of pentane. One common use of pentane is its use in the production of polystyrene and other plastics. Here, pentane is used to dissolve the polymer, which is then extruded into sheets or molded into various shapes. The solid plastic product is then left behind when the pentane evaporates. Pentane is also useful as a refrigerant in some cooling systems, such as refrigerators and air conditioners. This is because it has a low boiling point and can absorb a lot of heat when it evaporates. It can also be used as fuel in some engines, such as in model airplanes and cars. Pentane also acts as a binary fluid in geothermal power stations.

What is Cyclopentane

Cyclopentane is a cycloalkane with the molecular formula C₅H₁₀. It is a colorless, flammable, and volatile liquid with a slightly sweet odor. Cyclopentane consists of a unique ring-like structure that is composed of five carbon atoms arranged in a pentagon shape, with each carbon atom bonded to two hydrogen atoms. The carbon-carbon bond length in cyclopentane is approximately 1.53 angstrom. The boiling point of cyclopentane is 49.2 degrees Celsius while its melting point is -94 degrees Celsius. It is highly inflammable. It evaporates quickly at room temperature as its vapor pressure is high. Cyclopentane is soluble in organic solvents such as ethanol, acetone, and benzene. It is insoluble in water. The molar mass of cyclopentane is 70.1 g mol^-1, while the density of cyclopentane is 751 Kg m^-3.

Cyclopentane has many applications. One application is its use as a solvent in the production of polyurethane foam. It is also used as a blowing agent in the manufacture of expanded polystyrene foam. It also acts as a fuel and aerosol spray and as a refrigerant.

Similarities Between Pentane and Cyclopentane

• Pentane and cyclopentane are both hydrocarbons.
• They are flammable compounds.
• Both are colorless.

Difference Between Pentane and Cyclopentane

Definition

Pentane is a straight-chain alkane with the molecular formula C5H₁₂ whereas cyclopentane is a cyclic hydrocarbon with the molecular formula C₅H₁₀.

Structure

Pentane is a straight-chain alkane with five carbon atoms bonded together with 12 hydrogen atoms, while cyclopentane has a unique ring-like structure that is composed of five carbon atoms arranged in a pentagon shape, with each carbon atom bonded to two hydrogen atoms.

Melting and Boiling Points

The boiling point of pentane is 36 degrees Celsius, and its melting point is -130.5 degrees Celsius, while the boiling point of cyclopentane is 49.2 degrees Celsius, and its melting point is -94 degrees Celsius.

Molar Mass

The molar mass of pentane is 72.15 g mol^-1, whereas the molar mass of cyclopentane is 70.1 g mol^-1.

Density

The density of pentane is 626 Kg m^-3, while the density of cyclopentane is 751 Kg m^-3.

Applications

Pentane has various uses, such as in the production of plastics, refrigerants, and fuels, while cyclopentane is commonly used as a solvent in the production of polyurethane foam, as a blowing agent in the manufacture of expanded polystyrene foam, and as a fuel and refrigerant.

Conclusion

Both pentane and cyclopentane are hydrocarbons that are flammable. The main difference between pentane and cyclopentane is that pentane is a straight-chain alkane with the molecular formula C₅H₁₂ whereas cyclopentane is a cyclic hydrocarbon with the molecular formula C₅H₁₀.

Reference:

1. “Cyclopentane.” PubChem. National Library of Medicine. 
2. “Pentane – An Overview.” Science Direct. 

Image Courtesy:

1. “Pentane 3D ball” By Jynto (talk) – created with Discovery Studio Visualizer., CC0) via Commons Wikimedia
2. “Cyclopentane” By Rhododendronbusch – Self made, 07:41, 2 August 2005 (UTC) (CC BY-SA 3.0) via Commons Wikimedia