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Chemistry: Post your doubts here!

Aarjit

Aarjit

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smartangel said:
OH. so they want us to memorize the spectrum..that sounds weird. but anyway thanks:)
Click to expand...

I know.. but we have to learn it in quantum physics too [continuos and line spectra].

This will give you a rough estimate:
V I B G Y O R
400 - 700 nm
 
Romeo10

Romeo10

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Pleaseeeeeee guys can anyone tell me how do u balanceeee the equationnnn in Number 5 in N07 paper 4 pleaseeee help guysssss i just cant balance the equation
 
mr_perfect

mr_perfect

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Aarjit said:
The degenerate d-orbitals split because of the existent repulsion between the electrons. This helps to form transition-metal-complexes. While forming a complex with a ligand the d-orbitals interact with the surrounding electron cloud, causing it to become non-degenerate (variable energies). This causes photons to be absorbed by the electrons (which then undergo state transitions) to emit radiations with corresponding frequencies (f) to the energy (E) of the photons [where E=hf].

P.S. Electrons in d-orbitals are repelled from the electrons in the ligands, based on electrostatic interactions. This causes two of the d-orbitals (dz2 & dx2-y2) [which have a stronger (repulsive) interaction with the ligand] to be at higher energy than the other three (dxy, dyz, dxz).
Click to expand...

u say electrons absorb photon. where exactly do theese photons cum from ? and where does the radiation they emit go to ? . thnx for the knowledge btw :)
 
Aarjit

Aarjit

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mr_perfect said:
u say electrons absorb photon. where exactly do theese photons cum from ? and where does the radiation they emit go to ? . thnx for the knowledge btw :)
Click to expand...

Good questions. Allow me to answer them in bullets:
  • Photons can come from electron transitions or almost any source of LIGHT;
  • Electrons absorb the energy from photons and get promoted to discrete higher energy levels (this is also referred to as adsorption, but wanted to keep the rudiments simple);
  • The radiation/photons (ref. wave-particle duality) can then be used to excite other atoms in their ground states, or simply are visualized by our eyes (i.e. if their wavelengths happen to fall in the visible-light spectrum).
I hope that adequately clarifies your doubts. :)
You surely are pedantic, mr_perfect.*

*no pun intended ;)
 
mr_perfect

mr_perfect

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oldfashionedgirl said:
look, for finding heat of formation when enthalpy changes of combustion are given, the formula to use is pretty simple:
heat of combustion of reactant elements - heat of combustion of product

so if u substitute the values given u'll get the answer like this:

2(-393.7)+ 2(285.9) - (-1411) = +51.8 KJ/mol
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xcuse me oldfashionedgirl cud u change your profile pic please . tnx . it is very disturbing .:sick:
 
mr_perfect

mr_perfect

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tell me this. in group 4 tetrachlorides down the group the bond length increases right? that means bond strength increases right ? so isn't boiling piont supposed to LINEARLY increase down the group ? WHY DOES BOILING POINT NONLINEARLY DECREASE DOWN THE GROUP ????
 
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