Question

How would you solve for octahedral splitting?

Absorbed wavelength	Octahedral splitting	Formula
(nm)	(kJ/mol)
533	?	[Co(NH3)5Cl]Cl2
483	?	[Co(NH3)6]Cl3
510	?	[Co(NH3)5CO3]NO3

Answer 1

1)

Given
lambda = 5.33*10^-7 m

Find energy of 1 photon first

use
E = h*c/lambda
=(6.626*10^-34 J.s)*(3.0*10^8 m/s)/(5.33*10^-7 m)
= 3.729*10^-19 J
This is energy of 1 photon

Energy of 1 mol = energy of 1 photon * Avogadro's number
= 3.729*10^-19*6.022*10^23 J/mol
= 2.246*10^5 J/mol
= 2.246*10^2 KJ/mol
Answer: 2.246*10^2 KJ/mol

2)

Given
lambda = 4.83*10^-7 m

Find energy of 1 photon first

use
E = h*c/lambda
=(6.626*10^-34 J.s)*(3.0*10^8 m/s)/(4.83*10^-7 m)
= 4.116*10^-19 J
This is energy of 1 photon

Energy of 1 mol = energy of 1 photon * Avogadro's number
= 4.116*10^-19*6.022*10^23 J/mol
= 2.478*10^5 J/mol
= 2.478*10^2 KJ/mol
Answer: 2.478*10^2 KJ/mol

3)

Given
lambda = 5.1*10^-7 m

Find energy of 1 photon first

use
E = h*c/lambda
=(6.626*10^-34 J.s)*(3.0*10^8 m/s)/(5.1*10^-7 m)
= 3.898*10^-19 J
This is energy of 1 photon

Energy of 1 mol = energy of 1 photon * Avogadro's number
= 3.898*10^-19*6.022*10^23 J/mol
= 2.347*10^5 J/mol
= 2.347*10^2 KJ/mol
Answer: 2.347*10^2 KJ/mol