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vedmecum

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Posts posted by vedmecum

  1. what you wanna say about this ?

     

    1s - 1

    2s - 2

    2p - 3

    3s - 3

    3p - 4

    4s - 4

    3d - 5

    4p - 5

    5s - 5

    4d - 6

    5p - 6

    6s - 6

    4f - 7

    5d - 7

    6p - 7

    7s - 7

    6d - 8

     

    now we are got same n+l values for some orbitals , which is going to filled first ?

     

    so i feel Aufbau is the most general one .

  2. me and my friend amit performed this exp. in same lab . now we are trying to relate these abnormal color shift with CFSE (crystal field stablisation energy ) . we noticed that color shifted from high wavelength to low wavelength region i.e. with passage of time energy required to excite electron from low energy level to high energy level decreases . these will only happen if any other chemical species (may me O2 or any other ) attack on complex or the extent of bonding b/n Ni and DMG decreases . BUT THESE IS COMPLETELY AN APPARENT GUESS .

     

    waiting for comments .........

  3. No these is different from hypothermia . i think we need to relate it with transpiration . As in case of plants , transpiration results outer surface little cooler but internal temp. remain same . Same observed in humans when irritating sweat irritate .

  4. yesterday my friend gave me a beautiful cut on my palm and as nature's rule blood >:D.... my teacher advised me to apply FeCl3 an it really works . i don; know how ? please suggest me an appropriate ans .

     

    thanks:eyebrow:

  5. In an inert solvent, retention of configuration of the substrate is observed, whereas in the presence of certain other compounds, like pyridine for instance, inversion of configuration is observed.

    This is because the pyridine complexes with the HCl formed initially, and this makes the chloride ion free, and the chloride attacks from the back side of the leaving group (SO2 in this case)

    In the first case, after elimination of HCl, the Cl directly attacks the electrophilic carbon from the same side as the leaving group.

     

    why not Cl- attacks from the same side (in second case) as in case 1 ? i think the probable ans. is in 1st case , Cl of SOCl2 acts as nucleophile , these leads to cyclic intermediate and hence retention of configuration

     

    while in second case , pyridine or any base generate strong nucleophile Cl- which can attack only from back side as front side is blocked by cyclic intermediate .

  6. that is why i prefer to add KI (excess) . this increase the solubility of iodine in sol. and the loss of iodine will be minimized . if you perform the same in high light intensity , then you need not to put your sol. for more than 10-15 min .

  7. hydrogen bonding does not exist in hydrocarbons. Your book was wrong, or you misinterpreted it. Hydrogen bonding only occurs in molecules with a bond between a hydrogen atom and a very electronegative atom such as F, O or N, and sometimes Cl. Carbon isn't electronegative at all and so any molecules containing only hydrogen and carbon cannot contain hydrogen bonding.

     

    every element has some electronegativity .

     

    i think there is bit confusion on defination of hydrocarbon :- amit you have given an example of CHCl3 , which you can't count as hydrocarbon .

  8. hye . you can't calculate the exact percentage of the product by simple chemical equation because their are other factors which affect the reaction rate for ex relative proportion of h2so4 and hno3 , effect of bromine , and the most factor orientation i.e. o and para product . i know these makes your problem more complicated but ........

  9. one can purchase it from chem shop as it is not banned and it is also cheap i got pure sample of sodium acetate from my chem lab and did the same procedure as shown on youtube presentation . but i failed to get such type of ice .

    can anybody suggest me what mistake i probably did?

  10. dear jian , ionisation means removal of e- from atom this result in formation of ion , but the color is due to the excitation of e- from one energy level to another.

     

    and u are relating color to intensity of photon which is against both KIRCHOFF'S and Plank hypothesis. colour depends on frequency(wavelenth) of incident light.

     

    when light strikes on surface , atom or molecules or any other absorb some part of light of characteristic frequency(Kirchoff's law) and transmit other . absorbed light excite e- to higher energy state, and when e- comes back it emit that light .

  11. hye . copper oxide will not definetly form because copper is not able to displace H from H2O as this is below in electrochemial series.


    Merged post follows:

    Consecutive posts merged
    hye . copper oxide will not definetly form because copper is not able to displace H from H2O2 as this is below in electrochemial series.
    but i don't know the right ans.
  12. electronegativity is the tendency of an atom to attract shared pair of electron . fluorine has the highest tendency so it is assigned an electonegativity 4 and all other elements has lesser electronegativiy than fluorine . the appropriate scale is one developed by Pauling . and i think the charge dependency of electronegativity is completely wrong .

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