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Electronic Spectra in Coordination Chemistry

The most intense absorption band in the visible spectrum of [Mn(H20)6}2+ is at 24,900 cm-1 and has a molar absorptivity of 0.038 mol -1 cm-1.
What concentration of [Mn(h20)6]2+ would be necessary to give an abosorbance of 0.10 in a cell of path length 1.00.

Solution Preview

molar absorptivity a = 0.038 mol-1 cm-1
absorbance A = 0.10
path length b = 1.00 cm
concentration c(mol/L) = ?

Because,by Beer-Lambert Law

A = a * b * c
=> c = A/(a*b) = 0.1/(0.038*1.00) = 2.63 mol/Litre ...

Solution Summary

The solution uses the relevant law to calculate the concentration of [Mn(h20)6]2+ necessary to give an absorbance of 0.10 in a cell of path length 1.00 for the absorbtion band described in clear steps as well as providing a proof of the formula below.

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