Molecules Definition and 543 Threads

I would like to see how far I can get writing some novel & simplified simulator code for molecular modeling based on QM. ------ Background follows ---- skip to next post to get to the details of the project & starter QM question.. My son took chemistry this last semester (High-school...

can anyone tell me how i should approach this problem calculate the number of molecules of air in a beach ball of volume 6.0*10^-2m^3. The air is at temperature 35degrees, a pressure of 1.1*10^5Pa and can be trested as an ideal gas. i just want to know what area of classical physics it is

As you know I've been asking questions about alternative fuels and honestly its getting me no where, because I desire a lot more power than what our time has to offer with electricity and other things lol BUT if there is one thing i know about, it is a flippin car motor and how to make a lot...

If a diatomic molecule's vibrational energy is increased to the dissociation energy of that molecule, will that cause the molecule to rip itself apart? Is it the change in vibrational energy that causes the molecule to dissociate?

I think I did understand this once but now I am confused. If we choose the center-of-mass frame for a diatomic molecule, it also obeys the force law F=-kr, where r=(x,y,z), so why isn't it a 3-d harmonic oscillator, like an atom in solid? I know it may have something to do with the fact that gas...

An excellent laboratory vacuum has a pressure of 4.00x10^-18 atm, or 4.04x10^-13 Pa. How many gas molecules are there per cubic centimeter in such a vacuum at 297 K? n/v = p/rt n/v = 4.04x10^-13 / (8.31x297) = 1.66x10^-16 mol/m³ 1.66x10^-16 mol/m³ * (1/100cm)³ = 1.66x10^-22 mol/cm³...

Homework Statement What is the potential energy between the atoms in a body? Its a huge exercise, so I am not going to type the whole thing, but this is where I got stuck. Homework Equations You tell me. The Attempt at a Solution I found out what the temperature of the body was...

I know that KE=3/2KbT, but doesn't the KE of gas molecules also equal U=3/2nRT? When do I use which? And also for the second equation if it is for a monoatomic gas, n=1, why isn't the n deleted?

Homework Statement The mass of the deuterium molecule D2 is twice that of the hydrogen molecule H2. If the vibrational frequency of H2 is 1.22 × 1014 Hz, what is the vibrational frequency of D2, assuming that the “spring constant” of attracting forces is the same for the two species? Answer...

Homework Statement From the average separation between air molecules at STP, and their mean speed, estimate how long it would take one molecule to move into the region occupied by another. Assume that air consists mainly of nitrogen molecules. Homework Equations v(rms)=sq root(3kT/m)...

How easily do benzene molecules interact with london forces? I imagine that the relatively large surface area of the aromatic ring coupled with the pi-ring, which is a pretty large orbital makes london forces of a pretty large magnitude possible, but I am not certain. Does anyone have any...

1. A quantity of molecular hydrogen (H2) gas fills a one liter container at a temperature of 200 K and pressure of 1 atm. What is the average (rms) speed of the molecules? Homework Equations KE_trans = 1/2 M<v^2> Energy_trans = 3/2kT = 3/2RT H2 = 2g/mol The Attempt at a Solution...

Hi, I need to know what is the product I would get from the reaction between Linolenic Acid 8http://dl.clackamas.edu/ch106-06/images/fatty10.jpg) and Luteolin (http://upload.wikimedia.org/wikipedia/commons/archive/f/f9/20070124191456!Luteolin.png) I think Linolenic Acid would act as an...

This may seem like a simple question, but I am hoping to find a rather in depth answer. My father and I were discussing a lesson I had learned in Chemistry on Absolute Zero, when we got to the topic of why Molecules move. I answered him, that it was because they receive heat, and...

Dear all, Any quantum mechanical software (e.g., Gaussian03) can compute the fundamental frequencies (3N-6) and force constant for each frequency.. I don't understand exactly about force constant..?? For a particular mode of vibration what does this force constant mean? For a molecular with...

Hello guys, This might be a stupid question but artery has an inner endothelium and muscle outside. So if molecules diffuse out from the endothelium do they diffuse out of the muscle cells as well. How is that done, do muscle cells have the same membrane proteins as endothelium? Thanks :smile:

What do i and j stand for here? My teacher substituted them for masses (in our example, atoms in a molecule) although I'm not sure that makes sense since when you take the Hessian force constant matrix (on the next page of the link) I believe it must have dimensions determined by the number of...

hi before anything don't blame me much cause I'm chemical Eng & don't know physics much! I'm about to run a computer simulation which is strongly related to physics so I need your help. I need to simulate the motion of molecules when I heat them up likely a heavy liquid perhaps some...

Is it possible for one kind of molecule to be the cause of various odors? Maybe... this will happen when different parts of the molecule bind to the receptors in my nose?

1. You have a container of 3300 cm^3. Half of it is diatomic oxygen and half is monotonic helium. Pressure is 17 atm and temperature is 25 degrees C. How many molecules of each substance are in it? 2. PV = 2/3 N(1/2 mv^2) -> PV = 2/3 N (K) -> N = 1.5 PV/K K_monotonic = 3/2kT = 3/2...

Homework Statement "A perfect gas containing a single species of molecular weight M is in a container at equilibrium. Gas escapes into a vacuum through a small circular hole of Area A in the wall of the container. Assume wall container is negligibly thick and planer in vicinity to hole. The...

Homework Statement "A perfect gas containing a single species of molecular weight M is in a container at equilibrium. Gas escapes into a vacuum through a small circular hole of Area A in the wall of the container. Assume wall container is negligibly thick and planer in vicinity to hole. The...

Homework Statement 0.75 moles of NH3 molecules contain how many moles of hydrogen? Homework Equations The Attempt at a Solution

Homework Statement What is the number of moleules on human's body? Homework Equations The Attempt at a Solution Is this some kind of theory question and I just have to memorize it or does it involve calculation? I have tried searching a bit and found out that a person, about...

Since the water pressure at the bottom of the swimming pool is very high, are the water molecules there bouncing faster , or are they closer together?

Homework Statement A cubic centimeter of water has a mass of 1.00g. How many molecules does it contain? How many atoms are in 1.00g ice cube? Homework Equations 1 mole=6.02 x 10^23 molecules(or atoms) 1 mole of H20= 18g The Attempt at a Solution The answers are: 3.3 x10^22...

Homework Statement The rms speed of molecules in a gas at 20.0°C is to be increased by 1.4 percent. To what temperature must it be raised? k = 1.38E-23 (Boltzmann's Constant) Ratio in speed: 1.014 : 1 Ratio in Volume: 1.014² = 1.0282 : 1 T1 = 20°C = 293°K The Volume of 1 mol of an ideal...

Hey everyone, I'm not a math or physics major. I've just read a bit about quantum physics and find it interesting. If i understand it correctly, with the two slit experiment, when you send one particle at a time through without a particle detector by the slit, it results in an interference...

I took physics in high school many-many-many moons ago. Mr. Smith taught that molecules can only exist inside a three dimensional environment. Is that true?

temperature is the measure of average kinetic energy of the molecules of a gas , also temperature is the measure of hotness or coldness of a body , but how does this molecular motion motion produce heating effect that we can feel?!

How many molecules of H2O in 100kg of snow?? don't know where the density comes in! Homework Statement How many molecules of H2O are there in 100kg of snow? Density of snow is given as 800 kg/m3 Homework Equations 1 mole = 6.023x10^23 molecules mass/molecular mass = number of moles...

1. A canister containing 150kg of an ideal gas has a volume of 8 m^3. If the gas exerts a pressure of 5*10^5 Pa, what's the rms speed of the modecules? I can't get the temperature of the canister...

Homework Statement Given that the integral [between infinity and 0] v3e-av2dv = 1/2a2 calculate the average speed vav of molecules in the gas using the maxwell-boltzmann distribution function Homework Equations The Attempt at a Solution i don't really know what to do some...

I think the reason for molecules with 100 or so electrons to annihilate faster with a positron is because the electrons are quantum mechanicly smeared across a larger area.

Homework Statement determine the electron dot structure of molecules a and b http://session.masteringchemistry.com/problemAsset/1144353/2/MMAt.05.067.jpgHomework Equations The Attempt at a Solution A) ::O: H | | H-C=N-HB) H | .. H-C-N=C=O:: | H I am not at all sure...

Homework Statement The graph below shows all of the quantized energies (bound states) for one of these molecules. For this molecule, E0 = -2.5 eV, E1 = -1.20 eV, E2 = -0.72 eV, and E3 = -0.30 eV. What is the minimum amount of energy required to break a molecule apart, if it is initially in the...

Homework Statement Below about 80 K the heat capacity at constant volume for hydrogen gas (H2) is 3/2k per molecule, but at higher temperatures the heat capacity increases to 5/2k per molecule due to contributions from rotational energy states. Use these observations to estimate the distance...

Does the rms speed of a gas change when the no of molecules are lowered, isothermally? I know that at same temp, avg kinetic energy remains the same. m1 (v1)2 = m2 (v2)2 If m2 = m1/2, v22 = 2 v12 Is this correct?

Some chem students need help with homework problems similar to these later this week. and I want to make sure I've got the concepts down before I try to explain anything. This is for introductory chemistry. 1. Can a molecule have only nonpolar bonds and have a dipole? My first thought was...

Homework Statement A test tube of cylindrical shape having a length of 10 cm and a diameter of 2 cm contains 20 * 10 ^23 molecules (molecular size d = 3 * 10^-10 m). What is the mean free path of these molecules?? Homework Equations λ = 1/ pi * d^2 * n The Attempt at a Solution...

Homework Statement Explain why molecules in water at room temperature behave like classical particles. Homework Equations E = \frac{3}{2}kT = \frac{p^{2}}{2m} p = \frac{h}{p} \lambda = \frac{h}{\sqrt{3mkT}} for room temp, T = 300K. m is mass of water molecule k is boltzmanns...

I was browsing about the double slit experiment and found the following tidbit on Wiki: (emphasis mine) I knew that electrons could interfere with themselves - I understand how an electron can act like a wave. Even an atom I can understand. But a molecule? This isn't merely suggesting...

Homework Statement There are 3.344 x 10^25 molecules in 1 kg (1 litre) of water. What is the distance between the molecules? Homework Equations The Attempt at a Solution I found the density of water in kg/m^3, then found # moles in 1 litre (55.6) and then from that using Na I...

I've read in quite a few textbooks, chemistry and physics, that we can approximate a gas as many molecules which are floating in space and bouncing off each other. I want to know on what basis we make this approximation. What forces do we ignore and why? Here are some of the questions I...

Homework Statement http://img406.imageshack.us/img406/6418/problemo.jpg Homework Equations <V>=( Integral-from-0-to-inf(V*f(V)*dV) ) / ( Integral-from-0-to-inf (f(V)*dV) ) (second integral is for normalisation)The Attempt at a Solution http://img32.imageshack.us/img32/529/thermalphysics.jpg

I want to know if there is a way to push or disrupt air molecules around an object, or the device. Like some time of electrical field maybe? How would one attempt to go about creating a space evacuated of air around the device, with a field, or a vacuum nearing evacuation.

Homework Statement This question is about microwave (rotational) spectroscopy. Which of the following molecules have a microwave spectrum? H2, N2, NO, N2O, CH4, CO2, OCS, H2O, Ethene, Benzene. The Attempt at a Solution According to my textbook, it appears that all molecules have a...

Im trying to name the following molecules 1- CH3-CH2-CH-CH2-CH-CH2-CH2-CH3 l l CH3 CH2 l CH3 2- CH3-CH2-CH-CH2-CH-CH3 l l CH2 CH2...

Homework Statement Microwave oven I. The glass window isn't important to the microwave oven's operation, but the metal grid associated with that window certainly is. The grid forms the sixth side of the metal box that traps the microwaves so they cook food effectively. What is the approximate...

Homework Statement I am doing an exercise from my physics book right now. I am given: 1 molecule of hydrogen corresponds to 3.7x10^-26 m^3 1 molecule of led corresponds to 2.99x10^-29 m^3 the ratio of these volumes is 1.22x10^3 Q: Determine that the order of magnitude of the ratio...