The key difference between isopentane and neopentane is that the isopentane contains a four-membered carbon chain with one methyl group attached to this chain at the second carbon atom of the chain whereas the neopentane contains one carbon centre attached with four methyl groups.
Isopentane and neopentane are structural isomers of each other. Therefore, both these compounds have the same chemical formula; C5H12. However, due to the difference between isopentane and neopentane in their chemical structures, they have different chemical and physical properties. Another notable difference between isopentane and neopentane is that isopentane exists as a colourless liquid while neopentane is a colourless gas at standard temperature and pressure.
CONTENTS
1. Overview and Key Difference
2. What is Isopentane
3. What is Neopentane
4. Side by Side Comparison – Isopentane vs Neopentane in Tabular Form
5. Summary
What is Isopentane?
Isopentane is an organic compound having the chemical formula C5H12 and exists as a colourless liquid at standard temperature and pressure. The IUPAC name of this compound is 2-Methylbutane. Moreover, it is a branched alkane having a four-membered carbon chain with one methyl group attached to this chain, at the second carbon atom of the chain. Thus, it is an extremely volatile and flammable liquid.
Figure 01: Chemical Structure of Isopentane
More importantly, it is the least dense liquid at standard temperature and pressure. Therefore, the boiling point is just a few degrees above the normal room temperature. Hence it readily boils to form its vapour. The molar mass of this compound is 72.15 g/mol. The melting point and boiling points are within the range of −161 to −159 °C and 27.8 to 28.2 °C respectively.
What is Neopentane?
Neopentane is an organic compound having the chemical formula C5H12 and exists as a colourless gas at standard temperature and pressure. It is a structural isomer of pentane. It is a double branched alkane which has one carbon centre attached to four methyl groups. The double branch occurs at the middle carbon atom of a three-membered carbon chain.
Figure 02: Chemical Structure of Neopentane
The IUPAC name of this compound is hence 2,2-Dimethylpropane. Therefore, this molecule has a tetrahedral geometry. Moreover, it exists as a flammable gas at room temperature and pressure. As a result, it can condense into a highly volatile liquid on a cold day, if we put it in an ice bath or if we compress it applying suitable pressure. The melting point and boiling points are −16.5 °C and 9.5 °C respectively.
What is the Difference Between Isopentane and Neopentane?
Isopentane is an organic compound having the chemical formula C5H12 and exists as a colourless liquid at standard temperature and pressure whereas neopentane is an organic compound having the chemical formula C5H12 and exists as a colourless gas at standard temperature and pressure. Here, we have to note that though they have the same chemical formula; C5H12, they have different chemical structures. That is because they are structural isomers of each other. The isopentane contains a four-membered carbon chain with one methyl group attached to this chain at the second carbon atom of the chain whereas the neopentane contains one carbon centre attached with four methyl groups. Hence, this is the key difference between isopentane and neopentane.
Also, because of the difference in their chemical structures, we can identify some difference between isopentane and neopentane in their chemical properties too. Moreover, they both exist in different physical states as well. Isopentane exists as a colourless liquid while neopentane is a colourless gas at standard temperature and pressure. Therefore, this is another significant difference between isopentane and neopentane.
Summary – Isopentane vs Neopentane
Isopentane and neopentane are structural isomers of each other. Therefore they have the same chemical formula but different chemical structures. The key difference between isopentane and neopentane is that isopentane contains a four-membered carbon chain with one methyl group attached to this chain at the second carbon atom of the chain whereas neopentane contains one carbon centre attached with four methyl groups.
Reference:
1. “Isopentane.” Wikipedia, Wikimedia Foundation, 13 Aug. 2018. Available here
2. “Neopentane.” Wikipedia, Wikimedia Foundation, 4 June 2018. Available here
Image Courtesy:
1.”Isopentane”By No machine-readable author provided. (Public Domain) via Commons Wikimedia
2.”Neopentane”By No machine-readable author provided. No machine-readable author provided. (Public Domain) via Commons Wikimedia