Molecular Definition and 545 Threads

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 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...

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

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...

If the vapor of a liquid is NOT really ideal, how would this affect the calculated molecular mass?

Hi guys i came across molecular orbital theory and i don't understand why sometimes there is orbital mixing. For example B,C,N have no orbital mixing while O,F have orbital mixing. May i know how to know when there is orbital mixing?

In molecular orbital theory, there are two molecular states. (see below) I don't know the differences between these two states?

How would you determine which layer is which without using the densities?

Q: When water and chloroform, CHCl3, are mixed, the two components separate into two distinct layers, each of which smells strongly of chloroform. Account for these observations in terms fo the polarity of the two substances involved. Describe how you could very quickly determine which of the...

Hi, I thought that ClF3 is trigonal bipyramid or triangular bipyramidal. But it is not, so I don't know what it should be named in molecular geometry. Thank you so much to whom ever will answer my confusing thoughts right now! Thank you!

[SIZE="5"]Question Based on my background and interests, what graduate schools and programs would be best for me as a PhD-seeking biophysics student intending to ultimately study learning and memory? [SIZE="5"]Background I am a undergraduate in the USA that is preparing to receive four B.S...

Homework Statement The empirical formula of a compound is C3H2O. If the molar mass of this compound is 192.8, what is its molecular formula? 1. C12H8O4 2. C7H4O 3. C9H6O3 4. C15H10O5Homework Equations The Attempt at a Solution I'm having trouble with this question, I am not getting a whole...

Homework Statement Digiton is a substance that technologists use to determine cholesterol levels. It contains only (C,H, and O) and its percent composition is 54.71% C, 7.54% H, and 37.74% O by mass. The experimentally determined molecular mass is 1229g/mol. What is the empirical amd molecular...

I am having trouble identifying the difference between VB theory and molecular orbital theory. To me, they seem to be one and the same. In VB theory, two atomic orbitals overlap and share electrons forming a bond... Wouldn't this combination of two Atomic orbitals make a molecular orbital?

Molecular orbitals... don't get it Hi I'm new, to this forum and molecular science Reading a bit about molecular orbitals, and I have to say the whole concept of anti bonding orbitals and bonding orbitals got me quite confused. when atomic wave functions add you get bonding orbitals when...

Homework Statement I'm trying to do some numerical stuff with vibrations of H20 and I'm working in mdyne, angstroms, atomic mass units, and angles are given in radians. What would the corresponding unit of time be when I calculate my normal mode frequencies? femtosecond, 10e-15?

Nanotechnology, is a study of the control of matter on an atomic and molecular scale right? I'm currently studying taking this course in my college and I'm wondering if Nanotechnology plays a part in researching cancer cells. Does Nanotechnology helps in treatment of cancer cells? If...

Dear all, I am not sure if this is the right place to ask the following. (Moderators, please move this thread to the right sub-forum if necessary.) The question I am having is related to molecular dynamics. In the book "Molecular Dynamics Simulation: Elementary Methods" by J. M. Haile, a...

I have a few questions on molecular orbital theory which I hope you guys can help me settle! So I understand orthogonality meaning that the molecular orbitals have zero overlap, due to the Pauli Exclusion Principle. How do a 2s and 3s molecular orbital achieve orthogonality? Is it due to a...

Homework Statement \Delta9-Tetrahydrocannabinol (THC) is the primary psychoactive constituent of marijuana. Its metabolites include 11-hydroxy- \Delta9-THC (11-OH-THC) and 11-nor-9-carboxy- \Delta9-THC (THC-COOH). 1)Write down the molecular structure of these three compounds. 2)Develop an...

What do you guys think would be more fun particle physics or molecular biology? I love science and math and i love the idea of working on the most fundamental things of the universe, but i could do more practical things in molecular biology, so I am asking you guys what do you think?

In NMR for molecules, one can collapse the nuclear spin wavefunction \psi_{nucspin} by applying the magnetic moment operator \mu. That is, \psi_{nucspin} becomes one of the eigenfunctions of \mu. This physically corresponds to hitting the nuclei with photons in the radiofrequency range. In...

I get this formula in a MD paper:Wavelet-based multi-scale coarse graining approach for DNA molecules P(d)=A*exp(-U(d)/kT) P(d) is the distribution function, U(d) is the potentital. How does this formula come? In the paper I read about this, they get the distribution first, and obtain the...

Homework Statement A certain gas is at a temperature of 27 degrees Celcius. What would the temperature of the gas have to be to increase the rms speed of the molecules in the gas by 12 percent? Homework Equations V rms = √((3RT)/(M)) The Attempt at a Solution We know R and T...

Homework Statement Look up the enthalpy of formation of atomic hydrogen in the back of the book. This is the enthalpy change when a mole of atomic hydrogen is formed by dissociating 1/2 mole of molecular hydrogen (the more stable state of the element). From this number, determinethe energy...

This is the question I was given: "Describe the bonding within and between the molecules in liquid chlorine." I suppose the obvious problem is, I have no idea what the answer is. Any help will be appreciated! :D

Hello everybody, I currently have a degree in chemistry and I am working on another in physics. I plan on going to grad school when I finish the second degree. That will probably be in four years or so. I'm working full time for the next couple of years while taking classes and then I will...

Lambda is the quantum number for the total orbital angular momentum of the electrons about the internuclear axis. Unlike in atoms, the cylindrical symmetry created by the strong electric field of the nuclei in a linear molecule destroys the relationship [H ,L^2] = 0. Can anyone tell me...

Atoms have Terms Symbols such as S (L=0), P (L=1), D (L=2), etc...In case of molecules, L no longer exists as other symbols are uesd: which ones?

Hi, I have a little question about atomic models 1. Does Rydberg equation only apply to hydrogen 2. What is the purpose and limitations of molecular obitals

I've always wondered about this. Bimolecular fluorescence complementation allows the incorporation of fragments of the green fluorescent protein (GFP) at the N and C-terminus of separate monomers. If the monomers dimerize, the process allows the GFP fragments to come together and form a...