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<h2 class="title">The alkanes</h2>
<p>The alkanes are <a data-lesson="summarizing-hydrocarbons" data-subject="chemistry" data-tutorial="organic-chemistry" href="https://app.ulearngo.com/chemistry/organic-chemistry/summarizing-hydrocarbons">hydrocarbons</a> that only contain <em>single covalent bonds</em> between their carbon atoms. This means that they are <em>saturated</em> <a data-lesson="compounds-2" data-subject="chemistry" data-tutorial="quantitative-aspects-chemical-change" href="https://app.ulearngo.com/chemistry/quantitative-aspects-chemical-change/compounds-2">compounds</a> and are quite unreactive. The simplest alkane has only one carbon atom and is called <strong>methane</strong>. This molecule is shown in the figure below.</p>
<div class="wp-caption alignnone" style="width: 335px"><img alt="071e7db021c71869c6c023801dd17e62.png" height="146" src="https://data.ulearngo.com/assets/d28a38d5-deeb-4afb-85d3-5fbfbe9c119d" width="335"/><p class="wp-caption-text">The (a) structural and (b) molecular formula representations of methane.</p></div>
 

<p>The second alkane in the series has two carbon atoms and is called <strong>ethane</strong>. This is shown in the figure below.</p>
<img alt="ab7da8ce93b5d8bbe03cd6e520c3006a.png" src="https://data.ulearngo.com/assets/98e98456-0feb-49a6-86f1-4ad93f4efda6"/>
<div class="wp-caption alignnone" style="width: 800px"><img alt="" height="526" src="https://data.ulearngo.com/assets/c6b1958d-6a86-457a-87fc-d428025ba2f8" width="800"/><p class="wp-caption-text">The (a) structural, (b) condensed structural and (c) molecular formula representations of ethane. (d) An atomic model of ethane.<span style="font-size: 16px;"> </span></p></div>
<p>The third alkane in the series has three carbon atoms and is called <strong>propane</strong> (see figure below).</p>
<img alt="a13a6c52be35e36904ef886469363b37.png" src="https://data.ulearngo.com/assets/a8d1901d-c139-459c-b749-93c0823eb301"/>
<div class="wp-caption alignnone" style="width: 320px"><img alt="" height="215" src="https://data.ulearngo.com/assets/818cbfe0-29b8-4987-9290-0ee887418c69" width="320"/><p class="wp-caption-text">The (a) structural, (b) condensed structural and (c) molecular formula representations of propane. (d) A three-dimensional computer generated model of propane.</p></div>
<p>When you look at the molecular formula for each of the alkanes, you should notice a pattern developing. For each carbon atom that is added to the molecule, two <a data-lesson="hydrogen-reactions" data-subject="chemistry" data-tutorial="metals-metalloids-nonmetals" href="https://app.ulearngo.com/chemistry/metals-metalloids-nonmetals/hydrogen-reactions">hydrogen</a> atoms are added. In other words, each molecule differs from the one before it by \(\text{CH}_{2}\). This is called a <em>homologous series</em>.</p>
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<h3>Definition: Homologous series</h3>
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<p>A homologous series is a series of compounds with the same general formula. All molecules in this series will contain the same functional groups.</p>
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<h4>Fact:</h4>
<p>Some fungi use alkanes as a source of carbon and energy. One fungus <em>amorphotheca resinae</em> (also known as kerosene fungus) prefers the alkanes used in aviation fuel, and this can cause problems for aircraft in tropical areas.</p>
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<p>The general formula is similar to both the molecular formula and the condensed structural formula. The functional <a data-lesson="chemical-properties-of-the-groups" data-subject="chemistry" data-tutorial="classification-of-matter" href="https://app.ulearngo.com/chemistry/classification-of-matter/chemical-properties-of-the-groups">group</a> is written as it would be in the condensed structural formula (to make it more obvious), while the rest of the atoms in the compound are written in the same style as the molecular formula. The alkanes have the <strong>general formula</strong>: \(\color{red}{\textbf{C}_{\textbf{n}}\textbf{H}_{\textbf{2n+2}}}\).</p>
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<p>The alkanes are the most important source of fuel in the world and are used extensively in the chemical industry.</p>
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<p>Alkanes that contain four or less carbon atoms are <a data-lesson="introducing-gases" data-subject="chemistry" data-tutorial="gases" href="https://app.ulearngo.com/chemistry/gases/introducing-gases">gases</a> (e.g. methane and ethane).</p>
<div class="wp-caption alignnone" style="width: 492px"><img alt="" height="658" src="https://data.ulearngo.com/assets/c13dd448-5b0a-4b84-8bee-e05509cfa5d7" width="492"/><p class="wp-caption-text">(a) Methane gas bubbles burning and (b) propane (under high pressure) being transported by truck.</p></div>
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<p>Others are <a data-lesson="summarizing-properties-of-liquids" data-subject="chemistry" data-tutorial="liquids-and-solids" href="https://app.ulearngo.com/chemistry/liquids-and-solids/summarizing-properties-of-liquids">liquid</a> fuels (e.g. octane, an important component of petrol).</p>
<div class="wp-caption alignnone" style="width: 535px"><img alt="" height="355" src="https://data.ulearngo.com/assets/d19d1e52-7ac4-4bbb-9463-811d9c6e18de" width="535"/><p class="wp-caption-text">Liquid fuels that contain octane are kept in tanks at petrol stations.</p></div>
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The Alkanes

Chemistry generally explores the substances of which matter is composed, the investigation of their properties and reactions, and the use of such reactions to form new substances. 

Chemistry

Learn about the special properties of carbon, functional groups, isomers, IUPAC naming, physical properties, and reactions of organic molecules, as well as the formation and impact of polymers in this tutorial.


The Alkanes

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