|
Science and Astronomy Questions
|
|
| spacer | Date: Thursday, 20.10.2016, 03:02 | Message # 871 |
 Star Engineer
Group: Users
Israel
Messages: 1258
Status: Offline
| i always wondered how human voice would sound in different atmospheres and atmopsheres pressures.
even if they are toxic. 
"we began as wanderers, and we are wanderers still"
-carl sagan
-space engine photographer
|
| |
| |
| Watsisname | Date: Thursday, 20.10.2016, 05:27 | Message # 872 |
 Galaxy Architect
Group: Global Moderators
United States
Messages: 2613
Status: Offline
|
^This balloon does not contain helium.
|
| |
| |
| spacer | Date: Thursday, 20.10.2016, 06:51 | Message # 873 |
|
Star Engineer
Group: Users
Israel
Messages: 1258
Status: Offline
| Watsisname, hehe. how does Sulfur hexafluoride created?
i know sulfur can make 2 bonds like oxygen, so the thing goes up to my mind is that the sulfur lost 4 electrons, maybe ion?
but if it will lost 4 electrons it will also be able to make only 2 bonds like with Boron that can only make 3.
maybe i just still didnt study that cases
"we began as wanderers, and we are wanderers still"
-carl sagan
-space engine photographer
|
| |
| |
| Watsisname | Date: Thursday, 20.10.2016, 10:02 | Message # 874 |
|
Galaxy Architect
Group: Global Moderators
United States
Messages: 2613
Status: Offline
| Sometimes sulfur bonds with 2 electrons, but it has other oxidation states, too. To bond with six fluorine atoms it must share 6 electrons, so that is our clue. Now look to sulfur's electron configuration: it is equivalent to a neon atom, with additional electron shells 3s23p4. It is that entire shell of 6 electrons that gets shared to make SF6.
Another example is when sulfur bonds with four oxygen atoms to make SO4: it makes two double bonds and two single bonds, so it's actually 6 electrons being shared there as well.
Apparently, to synthesize it, they simply 'burn' the sulfur in fluorine gas. Probably not something you want to try at home.
Also interesting is that it is among the most powerful greenhouse gases known -- 24,000 times more powerful than CO2! Its concentration in the atmosphere is about 8 parts per trillion and increasing by about 0.25ppt per year. Which is so small as to be pretty much irrelevant to climate even given its potency, but it's neat that we can measure such small changes in concentration.
Back to the question of what we sound like in different atmospheres, it's basically all to due with the speed of sound in the gas as the video explains. The formula for the sound speed is
but of these factors the only one that would really be important for us is the molar mass. Air made up of larger molecules has a slower sound speed which makes our voices deeper. 
|
| |
| |
| spacer | Date: Thursday, 20.10.2016, 10:11 | Message # 875 |
|
Star Engineer
Group: Users
Israel
Messages: 1258
Status: Offline
| Watsisname, ohh cool we soon will start to learn about Redox and oxidation. so i yet to learn it.
but i love to learn it before in school, so it will be more clear to me when i will study it.
now sulfur has 6 electrons in his last electron shell (i think that how it translated to english from my langauge)
its: 2,8,6
and acording to Lewis structure of sulfur:
i learned that the only bonds can be formed with the single electrons (dots)
while the pair of the electrons cant (they allready a couple)
so in case of SF6 also the couples doing bonds?
if so its something new to me
hard to ask it in english  translate the the sentences i learned etc
"we began as wanderers, and we are wanderers still"
-carl sagan
-space engine photographer
Edited by spacer - Thursday, 20.10.2016, 10:21 |
| |
| |
| Mosfet | Date: Thursday, 20.10.2016, 13:41 | Message # 876 |
 World Builder
Group: Users
Italy
Messages: 754
Status: Offline
| ... and now we switched to redox equations... Watsisname, you really are a resourceful guy. I wonder if there's a pocket-sized version of you
"Time is illusion. Lunchtime doubly so."
Douglas N. Adams
My mods
Asus x555ub: cpu i5-6200u - ram 4gb - gpu nvidia geforce 940m 2gb vram
|
| |
| |
| spacer | Date: Thursday, 20.10.2016, 21:10 | Message # 877 |
|
Star Engineer
Group: Users
Israel
Messages: 1258
Status: Offline
| Mosfet, haha i need Watsisname, to sit next to me in class or come be teacher here
"we began as wanderers, and we are wanderers still"
-carl sagan
-space engine photographer
|
| |
| |
| Watsisname | Date: Friday, 21.10.2016, 02:53 | Message # 878 |
|
Galaxy Architect
Group: Global Moderators
United States
Messages: 2613
Status: Offline
| Eh, my knowledge shouldn't be overstated. I'm pretty good in a few areas, especially the natural sciences where my formal education has been, but I definitely don't know a lot about everything. I still have to do research and I am always learning, too. I think a desire for learning is one of the best things a person can have in life.
Quote spacer (  ) i learned that the only bonds can be formed with the single electrons (dots)
while the pair of the electrons cant (they allready a couple)
Yeah, this is a very good model for how bonds form, from the available unpaired electrons in the outer orbitals, and that the atoms 'want' to either fill or empty that outer shell completely. However, don't take this model as scripture. It doesn't always work that way. Here's a good example to think about (also using sulfur) -- try working out the electron dot diagram for the bonding of SO2. If you assume that only the unpaired electrons form bonds, then you'll have a tough time getting it to work.
A more useful model for this case is that something much more fluid happens.
Added: This probably seems really strange, since if you count up the electrons connected with sulfur, you get 10, not 8. To explain this, they're not quite double bonds, but also not quite single bonds. They're sort of in between. (Sometimes this figure is instead drawn with a double bond to one oxygen and a single to the other, but that gives an impression which is not quite correct, either.)
This 'model' of bonding also helps us understand the formation of SF6. Rather than those paired electrons staying that way, they spread out to all form single bonds with the unpaired electron in each of the six fluorine atoms. These bonds also spread out as much as possible in three dimensions, to produce an octahedral structure:
Which as a dot diagram we might represent as
or in faux-3D:
|
| |
| |
| spacer | Date: Friday, 21.10.2016, 04:48 | Message # 879 |
|
Star Engineer
Group: Users
Israel
Messages: 1258
Status: Offline
| Quote Watsisname ( ) If you assume that only the unpaired electrons form bonds, then you'll have a tough time getting it to work.
mmm i can think that the sulfur lost 2 electrons so its S+2 and now the sulfur is like carbon and can make bonds with 2 oxygens.
but i know that with ions, the Nonmetals are the ones that become - (minus) but maybe it can also be + (maybe i still didnt learn that)
ohhhh and wanted to say that meanwhile we learned only about nonmetals, and with metals we only learned about the first and second columns (Alkaline earth metal, and alkaline metals) while all of the metals in the middle of the table we still didnt learn about them because the electrons there act with different rules than the nonmetals ones like the 2,8,5 etc.
i will try write SF6 like with the notebook image and see if i do it well and understand it!
EDIT:
ok i tried to do it with my notebook, sorry about the mess. i wanted to show that the 2 electrons that not a pair in the sulfur become a pair and then every electron in some pair doing a bond with the flourine electron?
"we began as wanderers, and we are wanderers still"
-carl sagan
-space engine photographer
Edited by spacer - Friday, 21.10.2016, 05:12 |
| |
| |
| Watsisname | Date: Friday, 21.10.2016, 08:27 | Message # 880 |
|
Galaxy Architect
Group: Global Moderators
United States
Messages: 2613
Status: Offline
| Quote spacer ( ) mmm i can think that the sulfur lost 2 electrons so its S+2 and now the sulfur is like carbon and can make bonds with 2 oxygens.
Not a bad guess. However, this leads to a couple predictions which don't agree with observations. First is that the resulting SO2 molecule would have a +2 charge, while we know that in reality it is neutral. Second is that the SO2 molecule would be straight and nonpolar due to the symmetry, whereas we know it really is polar and bent.
Both of these observations tell us that those two electrons must still be there, and they must be on the sulfur.
You got the right idea with SF6. But don't think about it as each electron in an electron pair forming a single bond. Remember these electron dot diagrams are just a model. It is a useful tool for figuring out what the shape and bonding structure of a molecule is based on the sharing of electrons of the atoms that make it, but it doesn't tell you what each electron actually does as the molecule is formed. What the electrons 'really do' is some crazy quantum mechanics, and it's not too important for the chemistry.
If you'd like some more practice with these, give ozone (O3) a try. Hint: It is not a triangular loop!
Other hints: Count up the total number of valence electrons before you start (three oxygen with 6 valence electrons each gives 18 electrons to work with). All of these electrons should be accounted for in your final molecule -- either as bonds (2 electrons each) or electron pairs. Finally, feel free to move electrons around from atom to atom.
|
| |
| |
| spacer | Date: Friday, 21.10.2016, 08:32 | Message # 881 |
|
Star Engineer
Group: Users
Israel
Messages: 1258
Status: Offline
| Watsisname, i will try today! thanks.
for now i only know energy levels of the atmos with 2,8,5 for example, while the orbitals with S,P,D letters i still dont know.
maybe that what confuse me a bit because all around the internet with SF6 case i see ppl talk about the orbitals.
i will try O3 today evening and will post it here.
"we began as wanderers, and we are wanderers still"
-carl sagan
-space engine photographer
Edited by spacer - Friday, 21.10.2016, 08:32 |
| |
| |
| spacer | Date: Saturday, 22.10.2016, 17:15 | Message # 882 |
|
Star Engineer
Group: Users
Israel
Messages: 1258
Status: Offline
| http://www.physics-astronomy.com/2016....meh9670
and that how our understanding of our universe is reset!
need to study again!
"we began as wanderers, and we are wanderers still"
-carl sagan
-space engine photographer
|
| |
| |
| JackDole | Date: Saturday, 22.10.2016, 18:21 | Message # 883 |
 Star Engineer
Group: Local Moderators
Germany
Messages: 1742
Status: Offline
| Quote The discovery of the accelerating expansion of the universe won the Nobel Prize, the Gruber Cosmology Prize, and the Breakthrough Prize in Fundamental Physics. It led to the widespread acceptance of the idea that the universe is dominated by 'dark energy' that behaves like a cosmological constant – this is now the 'standard model' of cosmology.
If this proves to be true, will these prices have to be returned? 
Don't forget to look here.
|
| |
| |
| Watsisname | Date: Saturday, 22.10.2016, 23:24 | Message # 884 |
|
Galaxy Architect
Group: Global Moderators
United States
Messages: 2613
Status: Offline
| Quote spacer ( ) http://www.physics-astronomy.com/2016....meh9670
and that how our understanding of our universe is reset!
Nonsense. They did not reset a thing. They still found accelerating expansion, a non-zero cosmological constant (dark energy), and derive cosmological parameters consistent with those from WMAP and Planck. Their results are in agreement with the ΛCDM model of cosmology.
Let's look at their plot for uncertainty ellipses in the ΩΛ Ωm plane. ΩΛ is the mass density of dark energy. Ωm is the mass density of matter (both regular and dark). The combination of these which would produce constant expansion is the dashed line:
What is true is that they derived a smaller statistical significance for the accelerating expansion. Constant expansion is excluded to about 3 sigma. Which is not really surprising. From supernovae data at redshift between z=0 and z=1, the difference between accelerating expansion and constant expansion is very small. It doesn't become obvious until you get to redshifts of 2 and more, but that's in the realm of GRBs and quasars. So it is very hard to get high statistical significance from these data.
Fortunately, we have a lot of other data sources. To derive cosmological parameters and test various models of the universe, we use a combination of techniques:
-Supernovae
-Baryon Acoustic Oscillation (BAO)
-Cosmic Microwave Background radiation [CMB]
Each of these provide a different form of constraint on the values for how much matter and dark energy there is. Here's a plot with all of them together:
So, yeah. They haven't changed anything fundamental about our understanding of the universe. We're still very confident that it is expanding, that it contains dark matter and dark energy, and that the expansion is accelerating. The consensus values for ΩΛ and Ωm are around 0.7 and 0.3, respectively. Which is, without question, an accelerating universe, unless we overthrow general relativity.
|
| |
| |
| PlutonianEmpire | Date: Sunday, 23.10.2016, 00:35 | Message # 885 |
 Pioneer
Group: Users
United States
Messages: 475
Status: Offline
| How do I figure out how many hadley cells an alien planet may have, especially if it has different physical and atmospheric characteristics (such as radius, air temp, pressure, etc) than the Earth?
Specs: Dell Inspiron 5547 (Laptop); 8 gigabytes of RAM; Processor: Intel® Core™ i5-4210U CPU @ 1.70GHz (4 CPUs), ~2.4GHz; Operating System: Windows 7 Home Premium 64-bit; Graphics: Intel® HD Graphics 4400 (That's all there is :( )
|
| |
| |
ENG
New site
Israel 
United States 
Italy 
Germany