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  1. H

    Adiabatic Gas expansion

    Thank you! That ws really helpful!
  2. H

    Adiabatic Gas expansion

    ok, I will do that tomorrow when I get back home... what if my sheet here at school is asking me to calculate the work... like a numerical value? Do i just calculate one side of the equation?
  3. H

    Adiabatic Gas expansion

    Oh God, i keep forgetting to address your question. Yes, they were absolute pressures.
  4. H

    Adiabatic Gas expansion

    ok, so I got it down to ΔlnT/ΔlnP = 1 - 1/γ what do i do next? I am still puzzled as to how this is gonna help me find the work done by the expanding gas... :/ thanks though
  5. H

    Adiabatic Gas expansion

    so then, R ΔlnP = ΔlnT (Cv + R) ?
  6. H

    Adiabatic Gas expansion

    ΔU = Cv * ΔlnT = R * Δ(lnV) = R (ΔlnT - ΔlnP) do I keep going? Cv ΔlnT = R*ΔlnT - R*ΔlnP -> ΔlnT ( Cv - R) = - R*ΔlnP ? still lost... sorry :( (could you share a link where I can read about this topic, maybe i can save you some time if you could just direct me to the right topic)
  7. H

    Adiabatic Gas expansion

    Thank you. That is indeed very difficult to visualize... i can see the difference between this and piston that just allows the gas to expand rather than expand and escape. integrating gives me ΔU = nCv*ΔT = nRTln(v2/v1) is this correct? then what? do i use the left side of the...
  8. H

    Adiabatic Gas expansion

    I am having difficulties trying to understand the external pressure... You are saying that the pressure of the gas 'escaping' is now the external pressure of the gas that remains inside? How then do I calculate the work done by this expansion? w = nRT ln(v2/v1) ? but T isnt constant.. im very...
  9. H

    Adiabatic Gas expansion

    Also, we did not intend to reach any specific final or initial pressure reading (due to the difficulty of the experiment itself, holding the stopper of the flask was very difficult to do and thus we needed to be quick). Due to this, our readings vary a lot and thus the degree of expansion is...
  10. H

    Adiabatic Gas expansion

    well, i know the temperature change because the probe was measuring the temperature inside of the vessel at all times... what is the difference between a reversible and irreversible expansion... sorry but i took p.chem long ago and i forgot already some stuff... EDIT: Also, in a reversible...
  11. H

    Adiabatic Gas expansion

    Absolute pressure. The gas is allowed to expand against the atmosphere, no valve involved. Because the stopper was opened for a split second and thus some of the compressed air pushed against atmosphere (left the vessel) while still some remained slightly compressed. I think I didnt explain...
  12. H

    Adiabatic Gas expansion

    isnt the gas pushing against the atmosphere?
  13. H

    Adiabatic Gas expansion

    Sorry. The vessel had a stopper that you could open and let the gas expand... That's what i meant..
  14. H

    Adiabatic Gas expansion

    I have come up with something. Since w = p (V2 - V1) i am thinking.... w = p ( nRT2/P2 - nRT1/P1) ... assuming n = approximately constant... would this work? thanks
  15. H

    Adiabatic Gas expansion

    Homework Statement Hi, I did a lab experiment where I took a 5L vessel made of some material that isolates gas inside and thus behaves like an isolated system (adiabatic). I then pumped gas from ~90kPa to up to 150 kPa... recorded the temperature, then let the gas 'expand' by opening the...
  16. H

    Gel filtration chromatography

    Hi, I am studying for my biochemistry lab exam. While going over one of the questions... I came across one that I can't answer...help will be appreciated. Question under analysis is related to a previous question. (Previous question) A gel filtration (size exlcusion) is set up and the...
  17. H

    Momentum operator

    Thanks! I know it was something easy and silly. Thanks again.
  18. H

    Momentum operator

    This is not really a homework problem but rather a homework-related question.. When I came across my homework (and my textbook: Atkin's physical chemistry 9th Ed.), they defined the momentum operator as: p_x = - ( \hbar / i ) * d/dx... but i have seen in other sources that they define it...
  19. H

    Can anyone help me make sense of my lab results?

    Hello, I recently did an experiment of nanoparticles (specifically Au Nanoparticles) We did the Turkievich method and the borohydride method) for the turkievich method we got good results and this is indicated by the UV spectrum of the sample.. for borohydride though... we got a...
  20. H

    Electron Configuration

    Yes, I found this guy's explanation very accurate. Check it out. 'At the beginning of the first transition series (scandium), the 4s orbital is lower in energy than the 3d orbitals. Thus Sc has the configuration [Ar] 4s2 3d1. This continues as far as V which has the configuration [Ar] 4s2 3d3...
  21. H

    Equilibrium problem

    how did you come to the conclusion that it is ammonium phosphate? Not challenging you, but your answer my help me understand your procedure better and potentially help you.
  22. H

    Electron Configuration

    Borek is correct, the d orbital is close in energy to the s orbital so when an electro jumps from s to d, the energy is much less than jumping from a p or f to a d. They are close enough to allow this.
  23. H

    Selectivity of free radicals in halogenation.

    thank you, but still dont understand about selectivity... :(
  24. H

    Selectivity of free radicals in halogenation.

    Hi, can anyone please explain what selectivity of free radicals is? For example, there is an MCAT question that I recently came across and that can't seem to make sense of the answer. Which of the following halogens will give the greatest percent yield of tertiary alkyl halide when reacted...
  25. H

    Interference - two wave source

    Oh ok thank you again.
  26. H

    Interference - two wave source

    Thankss for replying, can you explain in more detail what you meant? are you saying that the difference in wavelengths must be a whole number otherwise the formula won't work?
  27. H

    Interference - two wave source

    Im sorry I didnt mean to get you upset or anything, but I wish to understand this fully for my upcoming test. They both arrive at 2.5 wavelengths so the interference is constructive I believe.
  28. H

    Interference - two wave source

    In the presence of the building, you can fit 1 wavelength, in the absence you can fit only half. Let me see if I get this, assume we move the building to the very end of the 40m length. So up to 30m, there are 1.5 wavelengths, but when the wave enters the building, then it can 'fit' one...
  29. H

    Interference - two wave source

    Thank you! you two are awesome, I am working on the one with the building, any help will be appreciated.
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