Using a cell with a path length of 1.00 cm, you recorded an absorbance of 0.452

Question

Using a cell with a path length of 1.00 cm, you recorded an absorbance of 0.452 for a solution of thiocyanate, Iron(III) and thiocyanoiron (the reaction is EQUILIBRIUM). Knowing that the absorptivity constant of FeSCN2+FeSCN2+ is 4700.0 L mol-1 cm-1 at the wavelength used, calculate the concentration of FeSCN2+FeSCN2+ in solution #1. If you dilute this solution in the cell with a small amount of water, would you expect the absorbance to increase, decrease or remain the same?

PLEASE ANSWER CAREFULLY, COMPLETELY AND LEGIBLY. MANY THANKS FOR YOUR HELP.

Explanation / Answer

absorptivity constant = 4700.0 L mol-1 cm-1

absorbance = 0.452

path length = 1.00 cm

absorbance = concentration x absorptivity constant   x path length

0.452 = concentration x 4700 x 1.00

concentration = 9.62 x 10^-5 M

from the relation : absorbance = concentration x absorptivity constant   x path length

absorbance increases with increase in the concentration of the sample from the above relation.

but concentration decreases with increases in volume or dilution .because molarity = moles / volume

so volume or dilution increases absorption decreases

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