Molecular Definition and 583 Threads

Homework Statement To show how conservation of angular momentum applied to to a collapsing MC core implies flattening during cloud collapse consider the equation of motion of a parcel mass m in a rotating initially spherical cloud of total mass M, initial angular speed w0 and radius r0...

I need to calculate the mean square speed of molecules in an ideal gas. Mean square speed is equal to 3RT/M, where M is the molecular weight. But what units do I use for the molecular weight if I use 0.08206 L.atm/(mol.K) as R? Thanks a lot.

DFT used electron density instead wavefunction, and in same time DFT use Schrodinger equation that use wavefunction. !?? so it still depend on wavefunction of Kohn-Sham and not depend on density only non interaction system wavefunction of still stand please I have many Paradox to...

Homework Statement 1.5000 g of diprotic weak acid H2A was dissolved in 100.00 mL volumetric flask. 25.00 mL aliqouts of this solution was titrated with a monoprotic strong base NaOH (0.08000 M). The titre volume of NaOH was 40.00 mL. Calculate the molecular weight of H2A. Homework...

Hi! I'm currently in 12th grade here in Hungary (= last year of high school), and have to decide which university I want to go to, and which course I want to take. I'm mainly interested in physics and a bit less in biology, programming and math. Don't get me wrong I like those as well, but...

NOT A HWK QUESTION! Molecular Theory PLEASE. Hi, Does anyone know the veracity of the quotation of experiments by Francis Bacon, in some books published around the turn of 20C., stating that he filled metal spheres with water and, upon applying sufficient pressure, saw water droplets on the...

Hi, Just wondering about the state of the literature regarding plane-wave molecular integrals. The coulomb potential seems to be causing problems for me. I assumed I would need to consider a general multipole expansion to integrate over a potential |r-r'|^-1 but I have had a look around and...

Homework Statement In his presentation of the de Broglie wavelength and the wave/particle duality, my quantum prof. has an exercise: "Find the de Broglie wavelength of a molecular vibration. Do quantum or classical laws apply?" Homework Equations wavelength = h/(momentum) ...

Homework Statement Greetings everyone I have been been asked to write a 10 page essay on Quantum Energy levels in atomic, molecular, nuclear and solid state physics. My problem is that this is such a huge topic and my knowledge of quantum energy levels and solid state physics is limited...

Now I'm undergrad student, majoring in Physics. But I think I prefer to be a physical chemist and want to be a university lecturer in department of chemistry. My research field is molecular biophysics and I need to have a basic knowledge of organic chemistry and biochemistry, but now I'm...

Is MO theory the most accurate model for atomic bonding we have so far? I've seen how it can be used to predict paramagnetism and diamagnetism but the idea of antibonding electrons and orbitals is seems fairly bizarre to me.

please tell me a quick for determination of empirical and molecular formula and also who invented it.

I don't know if this is a thermodynamics issue or a quantum mechanics one. It seems like there should be some relationship between the average heat and pressure of a system and the behavior of electrons orbiting nuclei. Does anyone know if there are any observations and experiments that have...

I know I know this isn't really related to molecular biology, but I figured since Biologists have a strong background in ecology in most cases, I'd be able to get more help here than the Earth forums (especially because biologists know a lot of chemistry). Basically I understand that CO2 keeps...

In my university (Catholic University of Leuven (Belgium) we have http://www.kuleuven.be/onderwijs/aanbod/opleidingen/E/SC_51017023.htm" with a few options: theoretical, nuclear, solid state, soft matter. I always wanted to do nuclear physics (and theoretical, but my math background isn't...

I have few questions regarding mercury vapor, except those related to health hazards. What is the mean molecular speed of mercury vapor at room temperature and speed of sound in a pure mercury vapor also at room temperature? Also, for the same density of air at seal level, can mercury...

Hello, I am interested in the electronic states of the N2 molecule. Now it is a homonuclear diatomic molecule and http://en.wikipedia.org/wiki/Molecular_term_symbol" ) but I do not understand what the Latin letters before the molecular term symbols mean. Here are some of the states X^{1}...

Could someone please help me get a very basic intuitive understanding of what rotational and vibrational quantum numbers mean? For simplicity, assume a diatomic molecule. For example, does a higher rotational quantum number mean that the molecule is rotating faster? Is the vibration number a...

From what I understand of nanotechnology, a lot of it is based around assembling individual molecules one by one to make superior materials such as graphene and nanotubes. If this is correct, will most materials be made out of carbon in the future (assuming that they are manufactured with...

Can someone explain to me, what are the factors/reasons that when certain atoms bond together, they form anti-Bonding or Bonding Molecular Orbitals? I am confused, and this is not in my syllabus(equivalent to Grade 12). P.S. It would be helpful if you included wavefunctions as well.

Homework Statement The relative motion of two atoms in a molecule can be described as the motion of a single body of mass m = 3 x 10-26 kg moving in one dimension, with a potential energy given by the equation U(r)=(A/(r^12))-(B/(r^12)) n this equation A = 10^10 J m^12 and B = 10^20 J m^6 are...

I understand half-lives, how various atoms decay through the various types of emissions (alpha, beta, gamma, etc). It's easy to do the math (or read the decay chain) for various things to see what the end-stable result if (eg U-238 and 235 decay to a thorium isotope, eventually to lead)...

what is the molecular formula of nitrite

Homework Statement A gaseous hydrocarbon weighing 0.185g occupies a volume of 110.cm^3 at 26 celsius and 743mmHg. what is the molecular weight of this compound? Homework Equations PV=nRT The Attempt at a Solution i have no idea where to start ;(

So I've always realized that organic chemistry and physical chemistry were huge gaps in my scientific background, and I still can't fill them up for some time, as I have many other subjects to study. But I've read large sections of molecular biology books (like Alberts and Lodish), and I've...

The question is as follows: A compound contains only carbon, hydrogen and oxygen. When 1g of the compound is reacted completely with oxygen, 2.2 g CO2 and 1.2 g H2O are obtained. The molar mass is close to 60. What is the molecular formula? I first wrote the equation: compound + O2 = CO2...

when a substance cools, its molecules vibrate at a slower speed and when a substance is heated its molecules vibrate quicker, right?. Is the increase in the molecules vibration a result of the heat energy being applied to it, or is it the increase in the vibrational energy of the molecule what...

Hey! How can we compute the molecular geometry for molecules and further use the VSEPR since electrons are continouly in motion, of which i actualy expected to hav temporary geometries ie. Oscilatin once an not a fixed or rigid which shows as if the system is static!

Homework Statement Ok, firstly, I apologise for posting something which is probably trivial to any physics student, but my understanding of physics is pretty poor, so baby steps would be appreciated! Homework Equations PV=nRT E = 1/2 mv2 The Attempt at a Solution My understanding of it so...

Glucose (C6H12O6) is a monomer that can form naturally occurring polymers. What would be the approximate molecular weight of a polymer made from 5 glucose monomers? a) 810 b) 828 c) 882 d) 900 i said D, but my friend in convincing me its B :S

Homework Statement What is the Empirical and Molecular Formula of caffeine, given these information: 0.376g caffeine would yield to 0.682 CO2 , 0.174g H2O and 0.110g N. The molecular weight if caffeine is 194 g/mole. Homework Equations --- The Attempt at a Solution 0.682 CO2...

Homework Statement The question involves a HI could in the ISM with an observed 21-cm emission line. I'm asked whether formation of molecular Hydrogen is likely. Homework Equations Not entirely sure The Attempt at a Solution First of all, I should say that this is a...

Hello, I am doing my undergraduate in the dept of 'mechanical design of intelligent systems' in Japan. During the fourth year we don't have any lectures and just work on research and our thesis. My field of research for the whole year will be molecular dynamics. Although this field uses...

Homework Statement I'm trying to figure out the electron pair geometry of NH3. I know that its molecular geometry is a trigonal plane, and it has 4 electron pairs total, including one lone pair.Homework Equations N/A just nh3 molecular geometry The Attempt at a Solution Should the e- pair...

The moderators here decided my explanation of evaporation was wrong, but they failed to explain why. They simply said I was an idiot and locked my thread. So... I ask the gods of physics here that moderate this board: How does evaporation work at the molecular level? Say you have a body...

Homework Statement An unknown compound contains 21.8 g of phosphorus and 28.2 g of oxygen. It's molar mass is 284 g/mol. what are its empirical and molecular formulas? Elements and the Weight: P = 31 g/mol O = 16 g/mol Given Measurements: 21.8g P, 28.2g O, MM = 284g/mol 2. The...

The specific heat at constant volume of an unknown solid is measured at high temperature to be 319.5Jkg-1K-1. Estimate its molecular weight. Cv=3R Attempt. I used the above equation to get a mass of the solid to be 0.0128kg but I have no idea of what to do next!

is there any corrolation between thermal conductivity coefficient and molecular wieght Mw according to the units [K] W/(m·K) it is independant of mass units (kg or g/mol etc) in my question i am asked to show with a graph, but i have no idea what graph they are talking about

Guys, The question is as follows: Q) I currently simulate organic systems using the Molecular Dynamics (MD) program. Previously, I have used MD to simulate primarily Silicon and Boron interaction at relatively high energies which is fine with the classical approach used with MD. I was...

which one of them has the strongest intemolecular bond CH4 ,Ne ,KI ,MgSO4 ,CO? there are london powers van der vals hydrogen bonds i don't know how to apply it here ?

I posed this thought experiment elsewhere, so the tone may seem a bit odd. It's based on what I've been reading on physical chemistry, atmospheric radiation and thermal physics. Just wondering if my interpretation is on the money or if I've made any incorrect assumptions. "Time for another...

Could someone explain the rudimentary parts of this model? Also, I don't understand how the Electron Configurations work for this. They seem to follow a particular pattern for certain elements and another pattern for other elements. Or is it the same for all elements? Here's what I think I...

Molecular Thermodynamics Hi guys, This is a molecular thermodynamics problem: can anybody help me on solving this problem? The vapor phase properties of propane are quite well correlated with a Lennard- Jones potential. Adjust the two Lennard-Jones parameters of methane to the following...

As simple as the questions seems, I can't seem to find an answer. 1. Can atomic hydrogen by chemical reaction, be converted to molecular hydrogen? 2. what happens when putting electrodes in a reaction that would give me atomic hydrogen? would it be collected at the cathode like molecular...

While both molecules have a very similar molecular weight, their boiling and melting points vary significantly. Explain the behavoir. i have look everywhere to try and figure out why the bp and mp are different from mw but i just can't get anywhere!

That's my question: how can I tell, from the molecular form of the compound, if a compound is an intrinsic semiconductor, an extrinsic type-N semiconductor, or an extrinsic type-P semiconductor? I can tell the pure intrinsic semiconductors: Si, Ge, C (diamond), etc. I know that if I add an...

Hey. Is there a sort of percentage known of how much mass in the universe is in molecular clouds compared to stars. I need this for a work I am doing. Thanks

Mods, I hope I'm not breaching any guidelines here, haven't had any responses in General Physicsand thought perhaps the question might be more at home here. I understand that CO2 molecules absorb infrared at 2.7, 4.3 and 15 microns, this makes them become vibrationally excited (rocking...

I understand that CO2 molecules absorb infrared at 2.7, 4.3 and 15 microns, this makes them become vibrationally excited (rocking, stretching, bending, I don't know all the modes). I have a few questions from this point: 1. When the CO2 molecule re-emits that energy is it obliged to do so...

Homework Statement I'm having trouble drawing a wedge-and-dash, 2 dimensional molecular structure for Vitamin C (ascorbic acid). All of the diagrams I've looked at (on the Wikipedia page, and some .edu websites) are incomplete: they either don't include the carbon and/or hydrogens molecules, or...