Wikipedia:Reference desk/Archives/Science/2024 April 9

= April 9 =

Mixing Ozone and Carbon Monoxide
I am having difficulty finding out what happens if you combine O3 and CO. As far as I can tell, O3 wants to be O2, and CO has no qualms about combining with other molecules. If I injected ozone into a airstream containing CO would the ozone seek it out to become O2 and CO2? Thanks,L3X1 ◊distænt write◊  02:53, 9 April 2024 (UTC)
 * It would not be seeking it out, but rather bumping into each other at random. The activation energy would have to be exceeded for a reaction to occur. This means that the gases would have to be warm enough. But a catalyst could make this happen faster. Graeme Bartlett (talk) 03:31, 9 April 2024 (UTC)
 * More in general, one should consider
 * p&thinsp;CO + q&thinsp;O3 ⇄ p&thinsp;CO2 + r&thinsp;O2
 * where p = 3q − 2r.
 * When (p, q, r&thinsp;) = (1, 1, 1), we have the case
 * CO + O3 ⇄ CO2 + O2.
 * In the troposphere, depending on the concentration of NO$x$, the reaction can go either way.
 * For (p, q, r&thinsp;) = (3, 1, 0) we get the reaction
 * 3&thinsp;CO + O3 ⇄ 3&thinsp;CO2.
 * I don't know under what conditions the reaction can be expected to go which way. --Lambiam 08:05, 9 April 2024 (UTC)
 * 3 CO + O3 ⇄ 3 CO2 would tend to run towards CO2; note that carbon monoxide can burn in oxygen and ozone decomposes into oxygen. That said, my understanding is that spin/conservation of angular momentum considerations can brake the oxidation of carbon monoxide, and you'd need a source of activation energy. Jo-Jo Eumerus (talk) 13:55, 9 April 2024 (UTC)
 * May be a little off-topic, but tragic experience has repeatedly shown that coal will slowly oxidise at relatively low temperatures in mines. Sometimes it only goes as far as CO giving the lethal White Damp, sometimes it goes all the way to Black damp which can be lethal by deprivation of oxygen.  If allowed to continue this slow relatively low temperature oxidation will start to heat the coal and eventually a mine fire can (rarely) occur. Martin of Sheffield (talk) 14:07, 9 April 2024 (UTC)
 * Would there be enough energy in the heat of exhaust gases from a jet engine to cause the reaction to happen? Thanks,L3X1 ◊distænt write◊  16:53, 10 April 2024 (UTC)
 * While still compressed in the exhaust, almost certainly yes, but the hot gas probably does not remain in the exhaust long enough for most of the molecules to engage in the reaction. I think the reaction speed can be calculated, but I do not know the theory needed for that. When the gas leaves the exhaust, it quickly gets decompressed and thereby undergoes adiabatic cooling. It will also mix with cooler air and get dispersed. --Lambiam 13:03, 12 April 2024 (UTC)

How to find a constellation...
...that a given right ascension and declination is in? Jo-Jo Eumerus (talk) 13:56, 9 April 2024 (UTC)


 * You could look here. For higher resolution I'd look in my copy of A Field Guide to the Stars and Planets, but I have the first edition and don't know how the later ones show this information. --142.112.220.50 (talk) 22:31, 9 April 2024 (UTC)
 * If the celestial coordinates are too close for comfort to a boundary in this image on the Commons, you can check the constellation boundaries defined by the IAU here. It is more work for some constellations (Draco!) then some others (Crux), but doable. --Lambiam 09:16, 10 April 2024 (UTC)
 * Note the following complication: The constellation boundaries were originally defined (for equinox B1875) such that the edges were ligns of constant right ascension or declination, so that the question could have been answered naively by a (in some cases lengthy) sequence of "less than" and "larger than" conditions. For J2000, the equinox that we're using now, this is no longer the case and a somewhat more sophisticated algorithm is needed. --Wrongfilter (talk) 10:00, 10 April 2024 (UTC)
 * How does the equinox impact the suitability of the (somewhat arbitrarily drawn) constellation boundaries? --Lambiam 14:53, 11 April 2024 (UTC)
 * What do you mean by "suitability"? The boundaries are still the same with respect to the stars, but the coordinates have changed due to precession. For Crux both eastern vertices (and the entire eastern edge) were at R.A. 12h50m, the western edges at 11h50m in B1875 coordinates (I think I have "east" and "west" correctly). In J2000 coordinates they are the R.A. values from the file you linked to; the values are of course different, and the edges are now also tilted with respect to a constant R.A. line. --Wrongfilter (talk) 19:33, 11 April 2024 (UTC)
 * As long as the coordinates of a spot on the celeastial sphere to be assigned to one of the 88 constellations are given with respect to the same epoch as those of the boundary list, everything should be fine. It seems simpler to me to adjust the coordinates of the spot than those of the list. --Lambiam 01:01, 12 April 2024 (UTC)
 * If you know and use Python, astropy has a function for that. --Wrongfilter (talk) 22:36, 9 April 2024 (UTC)
 * The celestial coordinates of constellations change owing to the precession of the equinoxes - the reference year shows the date of calibration. 2A00:23D0:443:BB01:EC7D:7F9E:B865:32A8 (talk) 15:08, 10 April 2024 (UTC)
 * The function uses the algorithm described in this paper by Nancy G. Roman. If you want to do it by hand, the tricky bit is to precess the coordinates you have (presumably in J2000) to 1875. This online tool can do that. --Wrongfilter (talk) 19:41, 11 April 2024 (UTC)
 * The algorithm in that paper is most suitable for being executed by a human computer. For an electronic computer, a version of the winding number algorithm may be simpler. --Lambiam 01:13, 12 April 2024 (UTC)
 * The astropy function that I referenced above implements the Roman algorithm for an electronic computer, the actual algorithm only needs a handful of lines, it uses boundary data that are a rearranged, but not precessed, version of the original definition. And it works. --Wrongfilter (talk) 08:47, 12 April 2024 (UTC)