# Are these gases related to each other? How? **URL:** \ **Category:** Factual Questions\ **Created:** [December 20, 2011, 2:01pm UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845 "2011-12-20T14:01:06Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![furryman](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/furryman/32/99_2.png) [@furryman](https://boards.straightdope.com/u/furryman)\ **Post date:** [December 20, 2011, 2:01pm UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/1 "2011-12-20T14:01:06Z")
Methane, Butane, Propane and Octane? ---
**Author:** ![Bill\_Door](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@Bill\_Door](https://boards.straightdope.com/u/Bill_Door)\ **Post date:** [December 20, 2011, 2:06pm UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/2 "2011-12-20T14:06:26Z")
Sure they are, they’re all hydrocarbons of different chain lengths known as alkanes. Methane is CH4, Butane is C4H10, propane is C3H8, and Octane is C8H18. The general formula for alkanes is CnH2n+2. ---
**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\ **Post date:** [December 20, 2011, 2:07pm UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/3 "2011-12-20T14:07:29Z")
> [@furryman](#): > > Methane, Butane, Propane and Octane? They are all [alkanes](http://en.wikipedia.org/wiki/Alkane). They are made of only carbon and hydrogen, and they have differing numbers of carbon atoms. ---
**Author:** ![aerodave](https://avatars.discourse-cdn.com/v4/letter/a/f08c70/32.png) [@aerodave](https://boards.straightdope.com/u/aerodave)\ **Post date:** [December 20, 2011, 5:13pm UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/4 "2011-12-20T17:13:23Z")
They’re not all gases, though…at least at room temperature and atmospheric pressure. Octane is a liquid at STP. ---
**Author:** ![cjepson](https://avatars.discourse-cdn.com/v4/letter/c/a9adbd/32.png) [@cjepson](https://boards.straightdope.com/u/cjepson)\ **Post date:** [December 20, 2011, 5:36pm UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/5 "2011-12-20T17:36:09Z")
> [@aerodave](#): > > They’re not all gases, though…at least at room temperature and atmospheric pressure. Octane is a liquid at STP. Thanks, that was confusing me… I was wondering how my gasoline could have octane gas in it! ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [December 20, 2011, 5:48pm UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/6 "2011-12-20T17:48:45Z")
Table of the properties of linear alkanes: [Alkane - Wikipedia](http://en.wikipedia.org/wiki/Alkane#Physical_properties) ---
**Author:** ![thelabdude](https://avatars.discourse-cdn.com/v4/letter/t/dc4da7/32.png) [@thelabdude](https://boards.straightdope.com/u/thelabdude)\ **Post date:** [December 20, 2011, 5:49pm UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/7 "2011-12-20T17:49:01Z")
Yes, octane is a liquid. They are chemically similar varying only in the number of carbons. They are all saturated. Butane and octane can form branched isomers. All are commonly used as fuels. The branched isomers of octane ignite more uniformly reducing knock when used as gasoline. There are countless other members of of the class going from gases, to liquids to solids as the number of carbons goes up. ---
**Author:** ![yabob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yabob/32/2821_2.png) [@yabob](https://boards.straightdope.com/u/yabob)\ **Post date:** [December 20, 2011, 5:53pm UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/8 "2011-12-20T17:53:41Z")
> [@aerodave](#): > > They’re not all gases, though…at least at room temperature and atmospheric pressure. Octane is a liquid at STP. And butane is so close to it that it liquifies very easily, for instance in cheap disposable lighters. ---
**Author:** ![mnemosyne](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@mnemosyne](https://boards.straightdope.com/u/mnemosyne)\ **Post date:** [December 20, 2011, 6:28pm UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/9 "2011-12-20T18:28:32Z")
> [@cjepson](#): > > Thanks, that was confusing me… I was wondering how my gasoline could have octane gas in it! Keep in mind that “gas” isn’t so much “a type of chemical” as it is 'the state a chemical happens to be in under certain conditions." Using a chemical that we are familiar with as an example, you know that water can change physical states depending on temperature and pressure. If you have a cup of liquid water and you store it in the freezer, you’ll get a solid - ice - but it’s still chemically the same thing; H[sub]2[/sub]O. You can boil water and it will become gaseous…but it’s still H[sub]2[/sub]O. If you capture that gas as it boils off, you can cool it down and get your cup of water back. These transformations from solid to liquid to gas state happen under predictable conditions; at atmospheric pressures (those we live in and experience every day) we say that water freezes at 0 degrees Celsius and boils at 100 degrees Celsius. Changing the pressure can cause those temperature points to shift up or down, and adding impurities (like salt) can change things too. Every chemical has defined freezing and boiling points under specific temperature and pressure conditions. So when you see a mixture like gasoline where you “know” that something is liquid but sounds like a gas, just think that the chemical(s) must simply be in conditions between their freezing and melting points. Some components might be in a gas form, but they are dissolved in a liquid: methane might be a dissolved gas inside the liquid octane - much like carbon dioxide is a dissolved gas inside the water of your Coke, making it fizzy. Does that make sense to you? I hope so!🆒 ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [December 20, 2011, 6:43pm UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/10 "2011-12-20T18:43:59Z")
> [@Bill\_Door](#): > > Sure they are, they’re all hydrocarbons of different chain lengths known as alkanes. Methane is CH4, Butane is C4H10, propane is C3H8, and Octane is C8H18. The general formula for alkanes is CnH2n+2. The number and variety of carbon-based compounds is staggering. There are categories (alkanes, alcohols, etc.) and naming conventions (compare (methane, ethane, propane, butane) with (methanol, ethanol, isopropyl alcohol, butanol) and it still gets spectacularly complicated. ---
**Author:** ![jayjay](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jayjay/32/6765_2.png) [@jayjay](https://boards.straightdope.com/u/jayjay)\ **Post date:** [December 20, 2011, 7:36pm UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/11 "2011-12-20T19:36:39Z")
> [@Robot\_Arm](#): > > The number and variety of carbon-based compounds is staggering. There are categories (alkanes, alcohols, etc.) and naming conventions (compare (methane, ethane, propane, butane) with (methanol, ethanol, isopropyl alcohol, butanol) and it still gets spectacularly complicated. Hell, it’s a whole branch of chemistry (organic chemistry) that’s actually vastly larger and more complicated than general chemistry. That amazed me when I was taking chemistry classes in college, that a single branch of chemistry devoted to the compounds of ONE element could so outpace everything else. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [December 20, 2011, 8:21pm UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/12 "2011-12-20T20:21:41Z")
> [@jayjay](#): > > Hell, it’s a whole branch of chemistry (organic chemistry) that’s actually vastly larger and more complicated than general chemistry. That amazed me when I was taking chemistry classes in college, that a single branch of chemistry devoted to the compounds of ONE element could so outpace everything else. it might seem like that as an undergraduate. chemistry is one of the sciences where what you learn as an undergraduate is like being in a wading pool. ---
**Author:** ![Bill\_Door](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@Bill\_Door](https://boards.straightdope.com/u/Bill_Door)\ **Post date:** [December 20, 2011, 8:39pm UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/13 "2011-12-20T20:39:27Z")
> [@Robot\_Arm](#): > > The number and variety of carbon-based compounds is staggering. There are categories (alkanes, alcohols, etc.) and naming conventions (compare (methane, ethane, propane, butane) with (methanol, ethanol, isopropyl alcohol, butanol) and it still gets spectacularly complicated. Tell me about it. I still wake up from nightmares trying to answer the question; “Using alcohols of four carbons or less and any necessary inorganic reagents, design a series of reactions to make the following compounds.” And then there’s a series of compounds beginning with the philosopher’s stone, phlogiston, and ending up with luminiferous ether. ---
**Author:** ![AWB](https://avatars.discourse-cdn.com/v4/letter/a/bb73d2/32.png) [@AWB](https://boards.straightdope.com/u/AWB)\ **Post date:** [December 20, 2011, 9:50pm UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/14 "2011-12-20T21:50:30Z")
> [@jayjay](#): > > Hell, it’s a whole branch of chemistry (organic chemistry) that’s actually vastly larger and more complicated than general chemistry. That amazed me when I was taking chemistry classes in college, that a single branch of chemistry devoted to the compounds of ONE element could so outpace everything else. From [Los Alamos National Labs: Periodic Table](http://periodic.lanl.gov/6.shtml) > [@](#): > > There are close to ten million known carbon compounds, many thousands of which are vital to organic and life processes. ---
**Author:** ![VOW](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/vow/32/3043_2.png) [@VOW](https://boards.straightdope.com/u/VOW)\ **Post date:** [December 21, 2011, 2:40am UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/15 "2011-12-21T02:40:20Z")
I wanna know how “organic” morphed from carbon-based chemistry (mostly petrochemicals, IMHO) to being “natural” with no chemical additives/fertilizers/pesticides. Doesn’t it seem strange that NON-organically raised crops are fertilized and treated for pests with organic compounds? ~VOW ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [December 21, 2011, 2:46am UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/16 "2011-12-21T02:46:40Z")
> [@VOW](#): > > I wanna know how “organic” morphed from carbon-based chemistry (mostly petrochemicals, IMHO) to being “natural” with no chemical additives/fertilizers/pesticides. > > Doesn’t it seem strange that NON-organically raised crops are fertilized and treated for pests with organic compounds? The definition of “organic” is “of, relating to, or derived from living organisms.” Organic _chemistry_ is about carbon-based molecules, because you find a lot of those in living organisms. Organic agriculture has nothing to do with it, except that both things have the word “organic” in them. Just keep in mind that if you want to afford the organic chem textbook, don’t buy the organic eggs. ---
**Author:** ![VOW](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/vow/32/3043_2.png) [@VOW](https://boards.straightdope.com/u/VOW)\ **Post date:** [December 21, 2011, 3:48am UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/17 "2011-12-21T03:48:08Z")
I took organic chemistry back when the dinosaurs still roamed the Earth (early Seventies). And that is when the big “organic” concept was beginning to blossom: people wanted everything “natural, wholesome, and pure.” Tell folks you’re taking organic chemistry, and you get, “Oh, wow, man, how cool is that?” THEN explain that organic chemistry means carbon-based, products of the petroleum industry. MAJOR disconnect! Even to this day, seeing the “organic” label on stuff in the grocery store makes me do a mental giggle. ~VOW ---
**Author:** ![GameHat](https://avatars.discourse-cdn.com/v4/letter/g/ed655f/32.png) [@GameHat](https://boards.straightdope.com/u/GameHat)\ **Post date:** [December 21, 2011, 4:16am UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/18 "2011-12-21T04:16:15Z")
It doesn’t make things any easier, but from a chemical engineering background you just consider all these things as “fluids” - as in, in any given system, depending on pressure, temperature and composition, there’s some liquid, some vapor, and it takes a healthy load of (imperfect) equations and formulae to figure out how much of each, and in which phase. /hey, there’s a reason this degree took five years. ---
**Author:** ![IvoryTowerDenizen](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ivorytowerdenizen/32/17937_2.png) [@IvoryTowerDenizen](https://boards.straightdope.com/u/IvoryTowerDenizen)\ **Post date:** [December 21, 2011, 4:19am UTC](https://boards.straightdope.com/t/are-these-gases-related-to-each-other-how/606845/19 "2011-12-21T04:19:05Z")
> [@VOW](#): > > I took organic chemistry back when the dinosaurs still roamed the Earth (early Seventies). And that is when the big “organic” concept was beginning to blossom: people wanted everything “natural, wholesome, and pure.” > > Tell folks you’re taking organic chemistry, and you get, “Oh, wow, man, how cool is that?” THEN explain that organic chemistry means carbon-based, products of the petroleum industry. > > MAJOR disconnect! > > Even to this day, seeing the “organic” label on stuff in the grocery store makes me do a mental giggle. > ~VOW That’s funny because when I think of organic molecules, the last thing I think of is “petrol products”. I think of the “molecules of life” (proteins, carbs, lipids and nucleic acids). That’s the biochemist in me, I guess!