Danielle has taught middle school science and has a doctorate degree in Environmental Health
What Is Pentane?
This is an organic compound that gives power to cars and helps make polystyrene foam (those foam peanuts found in your favorite package). I am referring to our friend pentane. Pentane is an organic compound in the alkane functional group with 5 carbon atoms bound to each other with single bonds. The molecular formula for pentane is C5H12. Alkanes consist of only carbon and hydrogen atoms with single bonds linking them together. As an alkane member, pentane has the distinguished honor of being a simple organic molecule.
When you see the liquid form of pentane you may mistake it for water—that is until you smell it! Pentane is a colorless liquid that has quite the offensive smell. It has a melting point of -129.8º C and boiling point of 36.1º C. With such a low boiling point, pentane is able to evaporate (poof!) into a vapor very easily at room temperature. A highly flammable compound, if it mixes with air as a vapor it can be explosive. These extreme personality traits of pentane place it in the category of being volatile. In fact, because of these volatile outbursts pentane is classified as a volatile organic compound.
Structure and Formula of Pentane
As mentioned previously, the molecular formula for pentane is C5H12. Here are representations of the pentane molecule.
The carbon skeleton looks like a stick drawing, and the 3-D image is show as different sized balls connected by sticks. As you can see, those 5 carbon atoms are present in a straight chain fashion. Remember, the single bonds linking carbon atoms to each other is what makes pentane an alkane.
Pentane has three different structural isomers. In other words, pentane has the awesome ability of camouflaging itself (without changing its molecular formula) into different structures. It can change into any three of these structural isomers or exist as a mixture of them. Those three isomers are n-pentane, 2-methylbutane (or isopentane), and neopentane (or 2-ethylpropane or dimethyl propane). Also, contrary to popular belief, cyclopentane does not have the distinct honor of being an isomer of pentane. This is due to the fact that the molecular formula cyclopentane is C5H10 which means that is has 2 fewer hydrogen atoms than pentane.
Now why would these structural isomers be important to remember? Believe it or not, physical properties such as melting and boiling point change from isomer to isomer. Would chemical properties of pentane change? I know you guessed this right; the answer is no. Remembe,r pentane's isomers only affect the arrangement of those carbon atoms. The arrangement does not change the number of carbon atoms or kind of atoms present in pentane.
There is one last note to make about these isomers. Did you notice that two of the isomers, 2-methylbutane and 2-ethylpropane, have branches shooting off the main carbon-carbon chain? Those branches (i.e. methyl, ethyl groups) are actually more stable than the first isomer n-pentane. This stability means less volatile outbursts from these isomers. They will have a lower temperature of combustion and formation.
Sources and Uses of Pentane
You may be wondering where you can find pentane. It is naturally found in the earth, primarily in crude oil and natural gasses. This means if you dig deep in the earth and find crude oil, you will find pentane gas if you light a fire to that crude oil and burn it.
So why use pentane anyway? Well, compounds containing pentane are quite useful in industry. Earlier it was mentioned that pentane plays a role in making foam. Pentane-containing compounds help create blowing agents, which are a major ingredient in making polystyrene foam. That type of foam is used in a wide variety of products from packaging those precious bowls you need to keep safe from breaking to home insulation. Whether it is helping you fuel your car or keeping that white foam cup sturdy as you drink away, pentane and compounds containing pentane can be of great use to us.
Pentane is an organic compound that consists of 5 carbon atoms single bonded to each other. It is considered to be an alkane and therefore a simple organic molecule. It is colorless, has an offensive smell, and is volatile. The molecular formula for pentane is C5H12. N-pentane, 2-methylbutane, and 2-ethylpropane are three structural isomers of pentane. 2-methylbutane and 2-ethylpropane are branched and thus more stable. Melting and boiling points change depending on the pentane isomer being used. Pentane is naturally found as a gas in Earth's crude oil. Compounds containing pentane are used to make a variety of products, such as polystyrene foam.
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