Molecular Definition and 545 Threads

What exactly is the concrete difference between those three?

Homework Statement Use the data: P/bar a: 0.1000 b: 0.5000 c: 1.000 d: 1.01325 e: 2.000 vs. density/(g/L) a: 0.1771 b: 0.8909 c: 1.796 d: 1.820 e: 3.652...for an unknown gas at 300K to determine the molecular mass of the gas...

Hi guys, If the value of v for which f(v) has its maximum value is known for a sample of a gas, is there a way of determining the corresponding maximum of f(E)/g(E)?

Homework Statement A sealed container of 0.10 m3 holds a sample of 3.0x1024 atoms of helium gas in equilibrium. The distribution of speeds of the helium atoms shows a peak at 1100 m s-1. Take the mass of a helium atom to be 4.0 amu. I, calculate the temperature and pressure of the helium gas...

Hope this is in the right place, apologies if not. We have studied green flourescent protein GFP and others (RFP, CFP etc) as a means of analysing an organism / sample, you need two that have unique fluorophores. We have also studied the use of FRET pairs such as florecein-florescien or...

I have thought the HCl is an ionic compound since it disassociates in water. However I read in my chemistry book that HCl is molecular. So what is it? Are all acids molecular or just the ones like HF, HCl, HBr, etc?

I understand photon absorption/emission by electrons in atoms, that transition them between energy levels, producing sharp spectral lines. However, I am having difficulty understanding photon absorption/emission by the vibrational and rotational modes of molecules, with respect to black body...

My general understanding of Molecular Orbitals is as follows: N atoms come together to form N molecular orbitals. N/2 of the orbitals will be spatially asymmetric with symmetric spins.This corresponds to the antibonding orbital. N/2 will be spatially symmetric with antisymmetric spins. This...

Homework Statement I'm trying to construct a molecular orbital correlation diagram for a tetrahedral compound [NiX4]2- considering the ligand pi-orbital basis. I've already constructed a diagram wherein the only the sigma-orbital basis is considered. In that diagram, I had 12 electrons for the...

Homework Statement Got a homework question for what kind of molecular structure you would get by combining these to metals: Thorium and rubidium, thorium and phosphour. Got to draw the Lewis diagrams and VSEPR model for these molecular structures, and predict the geometry - bond angles - bond...

Homework Statement When reacted with a small quantity of water, SiCl4 produces an oxychloride X, SixClyOz. The mass spectrum of X shows peaks at mass numbers 133, 149, 247, 263 and 396. You should assume that the species responsible for all these peaks contain the 16O, 35Cl and 28Si isotopes...

How would one go about estimating the relative position of the center of charge density (with respect to oxygen) in ruthenium oxide vs. silicon oxide? (Hypothetically) My real quandary is with the relative screening experienced by oxygen core electrons in silicon dixoide vs. ruthenium dioxide...

Hello, While I'm reading though various threads here on PhysicsForums, I thought I'd make a post asking for some advice/insight from those who have already gone though the process of finishing a degree and gained valuable life experience. I have a few questions which I'll post at the latter...

Can someone tell me What should I take in Community College to become a Molecuar Biologist? Should I take a Associates of Applied Sciences in BioTechnology or a Associates of Biology in Science(AS) or Associates of Science?However in the future I would like to work at a Biotech company,but I...

I am unable to prove step 8.3 in this proof of the path integral formulation of molecular dynamics https://files.nyu.edu/mt33/public/jpc_feat/node11.html Any help would be much appreciated.

Imagine a special air filter placed in a window of a house. The tiny holes in the filter allow only air molecules moving faster than a certain speed to exit the house, and allow only air molecules moving slower than that speed to enter the house from outside. What effect would this filter have...

The derivation of the ideal-gas equation included the assumption that the number of molecules is very latge, so that we could compute the average force due to many collisions. However, the ideal-gas equation holds accurately only at low pressures, where the molecules are few and far between...

If I have ice, water and vapour at the triple point and they are in equilibrium at a temperature of 273.16. Does this mean that the average kinetic energy of the particles is the same in each state? If so how can the molecules in the water be moving with the same mean squared speed as the...

Hello everyone, I will be entering my third year of university majoring in applied math and biology. I am currently looking for graduate school opportunities. My interest leans slightly towards the biology side but I am terribly worried about not getting a decent job after graduation if I do...

Dear All, I would like to know about (question related to computational chemistry): what is valence molecular connectivity index of 3rd order cluster. Please provide an example? Thanks for your help. Regards, Rajini.

I am interested in knowing whether what changes would happen at the molecular and atomic level, to a material subjected to Cooling. 1. Does the minimum temperature that can be achieved has limit? 2. Is it Zero Kelvin? 3. If so, is it a global standard for minimum temperature for any material...

In Molecular orbital theory, when two atoms A & B come close to each other, their atomic orbitals (say their s orbitals) combine and make two molecular orbitals, one bonding and the other anti-bonding. How about molecular orbitals of three or more atoms? For three atoms say A & B & C we would...

Hi, I'm an applied math major who wants to go to grad school for molecular biology. In my plan, I have included: Intro to cell biology & lab Intro to genetics Intro to microbiology molecular biology & lab advanced cell biology bioinformatics biological sequence analysis intro to...

Can anyone help with the following - which I have been musing about for some time. mThe general idea is that when heat is applied to a substance the molecules / atoms in that substance vibrate more and more (until the bonds in the molecule break). OK - so can anyone help with the following...

Hi I spotted on an MCAT book I am studying off of that the shading of the lobes(from a figure of p and sp3 orbitals) in an orbital represents the direction of spin for the electron and that in order for the electron density to overlap, the electrons must have the same spin. Firstly, I thought...

I am attempting to complete a basic question involving molecular separation from Alonso & Finn "Fundamental University Physics" Second Edition, Chapter 2, Question 9. The Problem states "Using the data in table 2-1 and A-1, estimate the average separation in molecules of hydrogen at STP (gas)...

I have read previous topics, but still the difference in compounds is not clear to me. As far as I understood, molecular compounds are made of covalent bonds, while ionic compounds by ionic bonds. I understand why Mn2O3 is ionic compound, because neutral Mn and O would make only MnO IN CASE...

hi! i have a doubt, how can i know the total number of bonding and antibonding electrons given a diatomic molecule's electronic configuration in therms of sigma and pi orbitals? I have to add these σ and π orbitals are of the type gerade and ungerade. does anyone can help me?

Hello all; I'm in an odd position. I graduated with a degree in molecular biology 2 years ago and now work in a quality control lab for a pharmaceutical manufacturer. My job involves doing things like running gene-amplification reactions for recombinant microorganisms used in drug-production...

Hi, I'm very interested in understanding how molecules in nutrition play a role in sustaining the human body so I'm looking for some good chemistry/molecular nutrition book describing some of the following: *The chemical and metabolic pathways taking place in the body (such as glykolysis...

I am a retired electrical engineer, now able to get back to studying what I really enjoy - mathematics and physics. As a genuine old geezer, my modern physics knowledge, which was never very deep, is now way out of date. I purchased a copy of "Modern Physics", by Kenneth Krane, and have been...

Homework Statement Consider a molecular system containing X type molecules and Y type molecules. X and Y can interconvert, and each has two energy levels (given below). The population in moles (n), of each energy state for X and Y, are given at equilibrium of T=300K. For X n0=0.8 and E0=0...

Hi I have a question regarding Molecular orbital theory: Is it correctly understood that if we combine 2 or more atoms the atomic orbitals can become 2 things: They can either become Hybrid orbitals which are the orbitals that form sigma bonds between atoms, or they can become Molecular...

I am making a human stem cell from its molecular components(just pretending to do it right now but might be able to do later in life). I have extracted my DNA and formed a liposome. I have the DNA replicating in an incubator at 98.6° F, 5% CO2, and 95% humidity. The temperature is because it...

Homework Statement Find the pH of 0.20 M Iron (III) sulfate. Homework Equations The metal ion becomes hydrated (water is a ligand) and forms iron hexahydrate. The sulfate ion is a weak base. The Attempt at a Solution Now, in considering the pH of this solution, should I consider the...

Hello Everyone, I understand that sometimes in physics we make a model of some physical system purely for theoretical convenience, as it allows us to calculate certain properties of the system very easily; although, sometimes these models aren't actually what is going on, but it doesn't matter...

A portion of an mRNA molecule has the sequence CCUAGGCUA. What is the sequence of the anti sense strand of the corresponding DNA molecule? The anti sense strand is the coding strand. The 3' to 5' strand from which mRNA builds. Does that mean the sequence would be backwards?

Hi, I am looking for online molecular emission spectra database for spectroscopic analysis of plasma. It would be great if searching in it is based on a wavelength of spectral lines/bands. For atomic spectra I found this database: http://physics.nist.gov/PhysRefData/ASD/lines_form.html But I...

I have a question about allowed transitions and molecular states. For an electric dipole transition between two states (say molecular or atomic) to have a non-zero probability of occurring, the transition dipole moment \langle \psi_{f}|\textbf{μ}\left|\psi_{i} \right \rangle must be non-zero...

http://chemwiki.ucdavis.edu/Theoretical_Chemistry/Chemical_Bonding/Molecular_Orbital_Theory/How_to_Build_Molecular_Orbitals Hi, I'm currently trying to understand MO theory and how diagrams are made and interpreted. I stumbled across this website and it shows the general MO diagrams...

Hello everyone. I'm am looking for some literature (articles or books) containing information about how is the relation between the liquid water pressure (macroscopic thermodynamic quantity) and it's quantum molecular dynamics (collisions, vibrations, etc.). Like: The pressure increase...

We have common detectors for radio, microwaves, visible, ultraviolet, xray and gammy rays.. but how about the infrared frequencies from molecular vibrations. The frequencies of molecular vibrations range from less than 10^12 to approximately 10^14 Hz. These frequencies correspond to radiation...

Does anyone know of a good code-oriented book on molecular electronic structure theory? I've been looking for a good modern book that teaches how to write SCF code to solve simple cases of the kind of problem that standard quantum chemistry packages (e.g. Gaussian, Orca) are used for without...

A compound contains boron (40.3%), nitrogen (52.2%), and hydrogen (7.5%) - by mass. If 6.32g of this compound if dissolved in 100g of benzene, the solution freezes at 1.30 celcius. If the cryoscopic constant is 5.12 and freezing pt of benzene is 5.48, what is the molecular weight of compound...

Molecular Vibration... I'm not sure if this is a Chemistry question or a Physics question. Please take time to correct me if I have posted in the wrong area. How do you find the frequency which a certain molecule vibrates? Like Melanin, or Serotonin, or Insulin. My brother and I are...

Homework Statement What is the electron pair geometry of the following? SCN− BeCl2 O3 The Attempt at a Solution SCN− Linear BeCl2 Linear O3 Trigonal Planar Homework Statement Would the following structures be polar or nonpolar? (Not applicable if the structure is an...

Homework Statement Number 17: http://i.minus.com/jbqSc694thPeBA.jpg Homework Equations I'm not even sure where to start. The Attempt at a Solution I know that tetrahedral shapes are non-polar if all of the attached elements are the same (e.g. CH4 or CCl4). I know all the answer...

Hello, a newbie here. I need to understand the relationship between MO and Energy Bands. Although i have searched and researched about this topic in Google, but i am yet to understand this part clearly. It is said that Energy Bands occur as the number of MO increase due to the various...

Homework Statement An unknown organic compound was analyzed in a carbon-hydrogen analyzer. The combustion of a sample of the compound produced 35.2 g of carbon dioxide and 18.0 g of water. The molar mass of the compound was found to be 116.28 g/mol. Determine the molecular formula of the...

Hi forums. I have what I think is a simple question but I'm making myself confused. I'm trying to work out the relationship between energy density ( u = energy per unit volume ) and temperature in a multi-species ideal gas (no molecules just different mass ions). The simplest example of...