Formation Definition and 480 Threads

How would you calculate the standard enthalpy of formation of N2O5(g) in kJ/mol from the following data (all species are gases): 2 NO + O2-----2 NO2 ∆H° = –114.1 kJ 4 NO2 + O2-----2 N2O5 ∆H° = –110.2 kJ N2 + O2------2 NO ∆H° = +180.5 kJ Any help is greatly appreciated!

I was just wondering if somebody could check to make sure my logic is correct for this lab exercise. The setup is basically this: using an ophthalmoscope, a doctor can peer into the pupil of a patient to view the retina and innards of the eye. The opthalmoscope is a device with a built-in...

Got a question about the energy dissipated during the formation of hydrochloric acid, upon the reaction of hydrogen and chlorine (photochemical reaction). Whats the exothermic energy involved and the intensity of light needed to activate this reaction, in other words the activation energy. And...

:redface: How is White light form? I know that it is a combination of 7 colours...But just want to know how the 7 light with different frequencies merged?

i have tow questions from eth question list which I think will be present in this exam..Would you please tell me 1.when teh babies brain will be formed in mothers ? 2.if any, how a smoking mother would afftec her child's brain at that time ? Thank you so very much if you could offered me...

Dissolve a chloride into a water, add excess nitric acid, then pour silver nitrate solution. A white precipitate is formed. What's it ?

Has there ever been a hypothesis or theory propsed (current or obsolete) proposing that the rocky planets formed from gas giants whose ring system collapsed and combined with the core of the gas giant forming the bulk of a new rocky planet? Just wondering if this has ever been proposed or...

In ammonia, why the N atom is sp3 hybridized and not sp2 hybridized...since there are only 3 bondings... Also, in ethyne, that is H-C(triple bond)C-H...for the formation of 2 pi bonds, why it is the unhybridized 2px orbital and 2py orbital of each C atom overlap with each other? How about the...

Hi I've been reading a lot about esters and have the general idea but I am not sure about exact amounts of acid catalyst needed. say the following experiment was tro be carried out to form an ester R-C=O(O-R2) *X moles of R-C=O(OH) *10X moles of R2-C-OH *How much H2SO4 would be needed? i...

Hi all, I'm a sixth year student in Scotland hoping to go onto study astrophysics at university. Keeping with this i have chosen to do my project on the formation of craters from meteor impacts. I am wondering if anyone could direct me to a site or suggest some advice on going about this...

According to the big-bang model, it is assumed that when the universe was young enough (lets say z > 1100), the density fluctuations did evolve in the linear regime. Due to this fact, one can make use of simple linearized formulas such as the continuity, Poisson and Euler equations to model the...

how are lines of induction formed due to 2 horseshoe magnets that are placed side by side but no contact? Are there websites that would show me about it?

In the nucleus of a spiral galaxy the most stars are old population II stars, and there is no star formation (which occurs in the spiral arms). Why? Thanks.

Can someone tell me which is the favoured theory for planetary formation, core accretion or Gravitational instabilities, and if these are the only valid theories?

[FONT=Comic Sans MS] Okay, this is a general question.. i just read this thread (https://www.physicsforums.com/showthread.php?t=28343) and started wondering about it. THis planet is considered "young", and it is a million years old. SO, my question was why does planet formation take so long? i...

Ok, a lens is held upright with a piece of clay. In front of it is a bulb, and behind it is a screen at the location of the image of the bulb. Now, what would happen to the image if the top half of the lens were covered by a mask? And what if the mask had a small hole in the center and were...

how is a black hole formed exactly from a neutron star or a white dwarf?? what is it? is it a star? is it defined as a matter?? and what happens when light gets sucked into it? there ought to be an increase in energy in it right? what happens to this energy?

stars are formed from gas clouds, these gas clouds posses potential energy and kinematic energy, they may also exhibit a density contrast, theory tells us that collapse of the gas cloud starts when PE overcomes KE, but i can find no explanation for the trigger to this collapse ,put another...

This is my first post, so I am going to get straight into a double barreled question that has been bugging me for a while. (1) How long does it take for stars to conglomerate around a general loci, in order to form a proto-galaxy. ? I ask this in the light of the most recent Hubble images...

Hi. I was reading through my organic chemistry book and they had a little piece on carbonic acid. So CO2 reacts with water and produces carbonic acid, very nice, I read about this before. But now that I've been enlighted with organic chemistry and the idea of mechanisms behind every reaction I...

At standard temperature and pressure, what is the heat of formation of water vapor?

In the experiment that I did today, there's a very strange step. After mixing two solutions in a beaker, according to the lab manual, we needed to scratch the bottom of the beaker using a spectula so as to help forming ppt. My question is why does scratching the beaker help forming ppt?

I wrote this short article for my grandson concerning the formation of clouds at an atomic level. I would be interested in constructive criticism before I put it away until he gets older. If anyone is aware of websites or other sources of information concerning this subject, I would be...

"Wisconsin crop circle formation was not made by hoaxers." "A Crop Circle, an eyewitness, photos, recorded anomalies and a meeting with a member of "The USAF Special Crop Circle Investigative Unit"! On July 23-24, 2003, a private scientific research team documented physical evidence that...

"Mysterious lights were videotaped emerging from the thirty-seven circles discovered in young wheat below the Ridgeway at Ogbourne St. George, Wiltshire, England, on Sunday, June 15, in a pattern nearly 600 feet in diameter." http://www.earthfiles.com/news/news.cfm?ID=551&category=Environment

My question pertains to atmosphere. Forgive me if it sounds stupid, or obvious, but I just don't know how atmospheres come about. I understand how planetoids and planets are formed, but when/how does it get an atmosphere? Any help would be appreciated.

Greetings ! Some less popular theories, at this time, suggest that planets formed or at least began to form before the Sun had formed. I'm not sure that I agree with that, but it's worth remembering as another counter example to the idea I just thought about. Anyway, the idea I just...

Hi, I'm an amateur cosmologist/physicist and I was hoping that someone more well-versed in these areas may be able to comment on this idea that I have. Assuming space-time is quanitized and the universe is limited to 3 spatial dimensions (as in Loop Quantum Gravity), has any research been...

hi,was the formation of our galaxy inevitable after the BB or could there have been a different outcome, if the former is true then that implies that information or rules were stored pre BB, if the later is true what other outcome could arise. wolram.

If some of the people that frequent this area of PF could please post their findings and or opinions on this debate I would appreciate the input very much. Did the planets of our solar system form uniformly; basically at the same time, out of the same solar material? Or, did some form sooner...