Recent content by Einstein Mcfly

  1. E

    Standard corrections to GFE for uni and bi molecular rxns

    Sorry, I'm not talking about getting the sign of delta G, I'm talking only about the correction in going from 1 atm to 1M. In that case delta G is the difference between the Gs at STP plus the difference between the correction terms for each G. Clearly the effect of the correction term will be...
  2. E

    Standard corrections to GFE for uni and bi molecular rxns

    Hello everyone. I have a weird question regarding the calculation of free energy changes in a multi-step mechanism. Now, if you have a bunch of calculated free energies in gas phase at 1 atm (say, from an electronic structure program) and you want to model in solvent, you need to get them in a...
  3. E

    DFT Hybrid Functionals: Inclusion of HF Exact Exchange Energies

    There are times when certain DFT software packages provide a very poor initial guess on the density, and so running a single point HF calculations first to get a set of orbitals that is reasonable is sometimes recommended. That is an instance where running a HF calculation first is a good idea...
  4. E

    Change in concentration vs. reaction rate

    What you're describing is a unimolecular reaction. If you have a reaction that is more than just one thing changing on its own, you have at least a bimolecular reaction and you can't talk about it just in terms of a single concentration. The units of the rate constant are whatever they have to...
  5. E

    Can biofuel replace petro oil, or can petro oil be farm produce?

    Of course. Solid state catalysts, pyrolysis followed by upgrades etc. The process that occurs naturally to make petroleum out of living things is just removing the oxygen so that when everyone's favorite redox reaction occurs (that is, combustion) it's not already partially oxidized (that's why...
  6. E

    Can biofuel replace petro oil, or can petro oil be farm produce?

    This is a much more complicated issue than is being expressed here. Firstly, there are a number of ways that biomass derived chemicals can be "upgraded" into gasoline, jet fuel or diesel fuel. There are also calculations that, depending on the bio-fuel that you're interested in, the feedstock...
  7. E

    Differences between the triplet and singlet states

    Your conclusion is not general. It's not always the case that singlet spin multiplicity is higher in energy than a triplet. The things you listed all depend on the particular case.
  8. E

    Hot water freezes faster than cold?

    http://www.iflscience.com/chemistry/hot-water-freezes-faster-cold-and-now-we-know-why I thought that this had never been shown to happen with closed containers. I always thought that this was an issue of open containers allowing for evaporation and hence a smaller amount of frozen water, and...
  9. E

    Why molecules of small atoms have hybridization and the big ones don't

    This is a bit of an old thread, but just for anyone who comes across it, we should make it clear that "hybridization" is a model for explaining covalent bonding by simple localized orbitals which are simple superpositions of atomic orbitals. It's not that some molecules "do" it and others "don't...
  10. E

    VBT AND Schrodinger(not sure about spelling)

    To be clear, electrons are always described by their wavefunctions, which are abstract "probability distributions", but they can be localized, such as the instance of an electron striking a detector. In this case, the wave function is an eigenstate of the position operator and is described the...
  11. E

    VBT AND Schrodinger(not sure about spelling)

    I'm not sure I get the point of this post. Please elaborate.
  12. E

    Exchange energy of electrons in degenerate orbitals

    I'm not sure I understand your question. I don't think it's about "electrons wanting to exchange their positions", I think it's a mathematical factor that depends on the overlap of different orbitals.
  13. E

    Quantum mechanics in chemistry

    Doesn't Hund's paradox just apply to chiral systems? I thought his question was more about non-degenerate isomers (boat versus chair and all that).
  14. E

    Quantum mechanics in chemistry

    Each arrangement of nuclei for a given number of electrons will have its own wave functions (solutions to the SE for that particular potential). That wave function doesn't "know" anything about any other wave function based on any other potential (due to different coordinates for the nuclei or...
  15. E

    Quantum mechanics in chemistry

    The SE will give you energy spectra that you can then along with statistical mechanics to get macroscopic properties like pressure. As for isomers, what you specify in the SE are, as was mentioned above, potentials. These will depend on distances between nuclei and how many electrons there...
Back
Top