Wikipedia:Reference desk/Archives/Science/2023 December 30

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December 30

gallium and carbon

Hi. I was watching random science Youtube and came across videos of gallium showing its fascinating properties.

1. Upon reading "Gallium forms alloys with most metals" in the gallium article, now I'm curious which common metals are not reactive with gallium. Is there such a list out there?

I figured that the list of metals that alloy or react with gallium is so long that it would not be informative, hence why I'm looking for the inverse list.

2. I'm also interested in which non-metals do not react with gallium. In particular, I'm interested in whether carbon reacts with liquid gallium or not. So far, I found this paper[1] where solid carbon float out of an gallium magnesium alloy, so I'm guessing that elemental carbon do not react with gallium at all. But I'd like a confirmation on this.

3. In researching for the two questions above, I've been searching "gallium XXXXX" in google. This is slow and error-prone. I don't have specialized training in chemistry, so I am not able to correctly interpret the search results even. Is there a more efficient way of doing this search?

I'm guessing that one of the databases in List of chemical databases would be helpful here, but there is so much information on that page that I don't even know where to start. Liberté2 (talk) 03:10, 30 December 2023 (UTC)

@Liberté2: You can check phase diagrams at this Russian-language site (the data is reproduced from reliable sources). You can often search for papers by Googling "chromium gallium system" (or perhaps using chemical symbols like "Cr-Ga system"). The metals least reactive to Ga seem to be refractory metals like W. The Pergamon volume on the group 13 metals also says that refractory Nb, Ta, Mo, and "above all" W are most resistant to Ga. (That said, intermetallics between Ga and the former three are known.)

Carbide says that Ga, In, and Tl do not form carbides even though Al does. This seems to be the only nonmetal with no binary compound with Ga, as I can find references to GaB₁₂, and Ga reacts with Si and Ge. I haven't found if all the binary Ga–nonmetal compounds form on direct reaction of the elements under some conditions, though. After all, GaN only forms by such direct reaction at 1200°C per doi:10.1021/j150340a015. Double sharp (talk) 04:12, 30 December 2023 (UTC)

@Double sharp Thank you! Liberté2 (talk) 07:02, 1 January 2024 (UTC)

The forces acting on my cell phone

Okay, here's the setup: the layout of my current city was designed by a drunken mule two centuries ago and hasn't really been corrected since. That, combined with incessant construction and street repair, means that I often make use of my phone's GPS. When I do, I lay my phone onto the charging tray in my center console so that I can glance at the map if things get confusing (otherwise, I just use the audio). The charging tray is pretty small, so my phone only fits on it sideways, but that's okay since I have to turn my head a bit to see it anyway. Here's the thing: my phone constantly ends up with the picture inverted (i.e. top to bottom), making it hard to read and necessitating me angling up the phone until it corrects itself so I can lay it down. I am not asking about preventing this behaviour; I know I can just force the screen to always stay a certain way; my question is: why doesn't the phone correct itself? Clearly, the centripetal force while making turns tricks the phone into thinking it needs to right itself, but why does it only get fooled once and then stay that way? Once the picture is inverted, it won't correct itself until I fix it manually. Why doesn't the situation undo itself when I turn in the other direction? Matt Deres (talk) 15:37, 30 December 2023 (UTC)

It's not clear to me what you mean by "sideways" when you describe how the phone is positioned. If you mean that the long axis of the phone is perpendicular to the front-back axis of the car, then I would assume that the inversion is caused by braking rather than turning. In that configuration, braking would apply a force directed toward the front of the car and would cause the phone to think that that direction is "down". But the opposite force when the car accelerates is usually not as strong as the braking force, so may not be strong enough to convince the phone that "down" is now in the backwards direction. CodeTalker (talk) 18:48, 30 December 2023 (UTC)

Not quite, though it's hard to describe without images. Normally, your phone and your car would be in parallel (i.e. the top of your phone would be up and, if you laid it down, it would point to the front of the car), but the cradle is wider than it is long, so, when I lay my phone down, the top of the phone is pointed towards the passenger door. It starts off fine, but through the course of driving invariably end up so that, although the phone hasn't physically changed orientation, the display has been inverted so that the top of the screen is now pointed toward the drivers side. That is, the phone seems to think that the passenger door is now "down" and never switches back to the driver door being "down" (which is how it was physically placed initially). Matt Deres (talk) 02:57, 31 December 2023 (UTC)

You drive on one side of the road, either left or right, depending on your country. This means that one can expect a systematic difference in the centripetal acceleration between left turns and right turns. The turns to the passenger side are tighter. There may be a speed difference too. On roundabouts, the turns to and from the roundabout are tighter than the turn on the roundabout. Further, the road surface is normally not level, but running down to the sides of the road, to help drainage. That puts the passenger side a bit lower than the driver side. PiusImpavidus (talk) 10:23, 31 December 2023 (UTC)

Makes sense - thanks. Matt Deres (talk) 17:27, 2 January 2024 (UTC)

If you turn your entire phone around, does it flip again? It may be that it has a preferred orientation and it flips to than when laying down, meaning that it has nothing to do with the car. It is just a design of the phone's hardware. 12.116.29.106 (talk) 19:04, 2 January 2024 (UTC)

The auto-rotation stuff works based on input from the phone accelerometer. This only, as the name implies, detects acceleration. It can't tell absolute directions, up down left right. Hence, the phone OS can get "confused" by non-uniform acceleration in different directions; this happens for me sometimes just holding it. The simple solution is to just disable the auto-rotation. I know Android lets you; don't know about iOS. Web search for instructions if needed. Slowking Man (talk) 04:45, 4 January 2024 (UTC)

Wisconsinite barn owls

The maps say barn owls are found in only a small area of Wisconsin, which has a lot of farmland. The map also says they live in Washington, which barely has any farmland. Are there any sightings of barn owls north of their range in Wisconsin EAGLITIZED (talk) 17:30, 30 December 2023 (UTC)

Of course, into Canada, see this birdwatcher database entry. Abductive (reasoning) 17:58, 30 December 2023 (UTC)

By the way, I actually knew they live in Canada, I was asking if they were found anywhere in Wisconsin, besides the small south-central area. 2600:6C44:627F:5865:D028:C3FF:FE4B:8D02 (talk) 19:02, 31 December 2023 (UTC)

Um, look at the map... Abductive (reasoning) 20:49, 31 December 2023 (UTC)

Whenever the edge of the range of some species of bird doesn't coincide with a sharp edge in biotope, one can expect the edge of the range to be fuzzy too. Even when depicted sharp on the map. PiusImpavidus (talk) 09:53, 1 January 2024 (UTC)