# What gas is heavier than air? **URL:** \ **Category:** Factual Questions\ **Created:** [March 17, 2001, 3:50am UTC](https://boards.straightdope.com/t/what-gas-is-heavier-than-air/58334 "2001-03-17T03:50:28Z")\ **Posts on this page:** 10\ **Page:** 3
**Author:** ![eltro102](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@eltro102](https://boards.straightdope.com/u/eltro102)\ **Post date:** [March 10, 2013, 1:13pm UTC](https://boards.straightdope.com/t/what-gas-is-heavier-than-air/58334/41 "2013-03-10T13:13:30Z")
> [@ZenBeam](#): > > So are there any liquids lighter than the heaviest gas? Could I have a bucket with a light liquid floating on a heavy gas? not exactly in the way you wanted, but if you splash liquid nitrogen over warmer things, like your hand, the little droplets will float above it because they’ll be constantly exuding nitrogen gas which gives them a cushion (a bit like a hovercraft) ---
**Author:** ![Malacandra](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Malacandra](https://boards.straightdope.com/u/Malacandra)\ **Post date:** [March 10, 2013, 1:29pm UTC](https://boards.straightdope.com/t/what-gas-is-heavier-than-air/58334/42 "2013-03-10T13:29:26Z")
> [@eltro102](#): > > not a planet, but on titan the air is a lot denser than on earth, so any balloons would float up (and the gravity is a lot lighter too, so you could conceivably float using a bunch of earth air balloons) > the venusian atmosphere is a lot denser too, but the balloons would probably cause the air to combust and/or be crushed by pressure > pretty much the same thing on jupiter/saturn/neptune/uranus below certain altitudes Except that Titan’s atmosphere is mainly nitrogen, and the only reason why it’s denser at the planet’s surface is that the pressure is higher. But if you take a balloon there then it too will be subject to the same pressure, and the air in it will be just as dense as Titan’s nitrogen. The gas giants have a lot more hydrogen, methane and ammonia than Earth, so a less dense (per pressure) atmosphere than Earth, meaning once again that a balloon full of an 80:20 nitrogen/oxygen mix would still be heavier than the local “air”. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [March 10, 2013, 1:57pm UTC](https://boards.straightdope.com/t/what-gas-is-heavier-than-air/58334/43 "2013-03-10T13:57:43Z")
> [@snailboy](#): > > If you want to up the temperature some (168 F), xenon hexafluoride is quite the heavy gas with a molecular weight of 245. I’m guessing a balloon filled with that would hit the floor pretty quickly. Yeah, but that’s cheating a bit; it’s got to be a gas at standard temperature and pressure. Otherwise any substance that vaporizes at incandescent temperatures could be a contender. ---
**Author:** ![crucible](https://avatars.discourse-cdn.com/v4/letter/c/5f8ce5/32.png) [@crucible](https://boards.straightdope.com/u/crucible)\ **Post date:** [March 10, 2013, 3:00pm UTC](https://boards.straightdope.com/t/what-gas-is-heavier-than-air/58334/44 "2013-03-10T15:00:18Z")
> [@DaveRaver](#): > > If you put helium in a balloon, it rises because helium is lighter than air. My question is: what gas could you put into a balloon to make it sink like a stone? What gas is heavier than air? two minor points regards the discussion. Xenon is incredibly expensive and difficult to find. I doubt a HS or college or research facility would play with it. Argon, on the other hand, is one of the minor components of air and is, when separated, significantly heavier than ‘air’. Case in point. A place I worked almost had a fatality because they had a compressor in a low area inside the plant that was converted to pumping argon gas flashing off the liquid argon storage tank (the plant made, among other things, mixes of argon with other gases for various welding purposes). Compressing the flashoff into receivers, then using it to equalize with evacuated cylinders ready to fill would save the expensive argon from being wasted. The plant manager was inspecting the compressor because someone had reported a leak in the piping between compression stages… The leak was enough that it had filled the low area around the machine with mostly argon. He passed out and a worker noticed him and went in to see what was wrong. He passed out. The third person to come along realized that two men down meant a hazardous atmosphere and he sounded the alarm. Another man held his breath and went in to drag his buddy part way out. Another man did the same for the manager. After several tries, and some wooziness, they succeeded in getting the men out of the low area and reviving them. ---
**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:** [March 10, 2013, 5:54pm UTC](https://boards.straightdope.com/t/what-gas-is-heavier-than-air/58334/45 "2013-03-10T17:54:24Z")
> [@crucible](#): > > two minor points regards the discussion. Xenon is incredibly expensive and difficult to find. I doubt a HS or college or research facility would play with it. > > Argon, on the other hand, is one of the minor components of air and is, when separated, significantly heavier than ‘air’. > > … Nitpick - Xenon and Krypton are produced the same way Argon is - fractional distillation of liquid air. However, their concentrations are much lower - xenon is a REALLY “minor” component (Xenon is about 0.09 parts per million by volume, as opposed to about 9300 for Argon). Hence, yeah, it’s expensive. They also have to do additional distillation steps to extract xenon and krypton - they are initially trace “contaminants” in the oxygen fraction. If they weren’t commercially valuable, I suspect they would leave them there. A commonly quoted price for xenon seems to be about $120 per 100 grams. I suspect that’s the price you would pay through a scientific supply house for fairly small quantities. Not prohibitive for use in classroom demonstrations, but you’re spending several dollars to fill a small balloon with it. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [March 10, 2013, 6:28pm UTC](https://boards.straightdope.com/t/what-gas-is-heavier-than-air/58334/46 "2013-03-10T18:28:07Z")
Just throwing this in here because of turn towards processing of noble gases. Everybody in my introductory chemistry course reading this (were any of those words true) is thinking the obvious question: so what’s up with Kryptonite? From the long and detailed [Wiki on the subject:](http://en.wikipedia.org/wiki/Kryptonite) Under standard chemical naming procedures, the -ite suffix of kryptonite would denote an oxyanion of the element krypton. However, krypton is a noble gas that forms compounds only with great difficulty, and such an oxyanion is not known. Nevertheless, the University of Leicester presented the Geological Society with krypton difluoride to commemorate the 70th anniversary of Superman. No oxyanion: correct? Krypton diflouride: hard to make? Actually used for anything anywhere? What would lead the University of Leicester guys to choose Krypton diflouride as being the most Kryptonite-y?\* \*It’s also a crying shame that ferners had the wherewithal to do this and not 'Mercuns. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [March 10, 2013, 8:27pm UTC](https://boards.straightdope.com/t/what-gas-is-heavier-than-air/58334/47 "2013-03-10T20:27:45Z")
> [@Malacandra](#): > > enon’s actually an effective anaesthetic, and not merely an asphyxiant. That’s kinda counter-intuitive for a noble gas. Not in the least. Anesthetic ability for these sorts of substances is directly correlated with its fat solubility. It works exactly like nitrous oxide. No chemical reactivity required. So no high school demos with Xe. SF[sub]6[/sub] is typical. ---
**Author:** ![snailboy](https://avatars.discourse-cdn.com/v4/letter/s/97f17d/32.png) [@snailboy](https://boards.straightdope.com/u/snailboy)\ **Post date:** [March 10, 2013, 10:09pm UTC](https://boards.straightdope.com/t/what-gas-is-heavier-than-air/58334/48 "2013-03-10T22:09:30Z")
> [@Lumpy](#): > > Yeah, but that’s cheating a bit; it’s got to be a gas at standard temperature and pressure. Otherwise any substance that vaporizes at incandescent temperatures could be a contender. Yeah, it could be considered cheating which is why I made sure to mention the boiling point. However, it’s not so hot that the experiment couldn’t be done practically (if you could find enough of the chemical). The balloon should be alright at that temperature and I’ve heard of humans surviving when temporarily exposed to it or you could just take it out of an oven and quickly drop it. I figured it was worth a mention. ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [March 10, 2013, 10:23pm UTC](https://boards.straightdope.com/t/what-gas-is-heavier-than-air/58334/49 "2013-03-10T22:23:07Z")
A balloon filled with air on Venus would float. If you float it at the level in the atmosphere where the temperature is about the same as that found on Earth, the internal pressure will be around 1 atmosphere. That makes the atmosphere of Venus the second most habitable location in the solar system. See ‘Colonisation of Venus’ by Geoffrey Landis [http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20030022668\_2003025525.pdf](http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20030022668_2003025525.pdf) (pdf) ---
**Author:** ![Trinopus](https://avatars.discourse-cdn.com/v4/letter/t/2bfe46/32.png) [@Trinopus](https://boards.straightdope.com/u/Trinopus)\ **Post date:** [March 11, 2013, 2:20am UTC](https://boards.straightdope.com/t/what-gas-is-heavier-than-air/58334/50 "2013-03-11T02:20:17Z")
> [@samclem](#): > > **DDG** Air weighs the same as air. Therefore the balloon wouldn’t sink or rise. > > But if you _blew it up_, perhaps the carbon dioxide you expelled into the balloon would be heavier than the _air_ and it would sink. Also, compressed air weighs more than air at ordinary “room pressure.” So when you fill a stretchy rubber balloon, you have to blow hard (hey, I’m good at that) and the air is now compressed. So that, too, is part of why the balloon falls to the ground. (You also have the weight of the rubber to contend with…) [Previous page](https://boards.straightdope.com/t/what-gas-is-heavier-than-air/58334.md?page=2)