Question

In a different titration, the absorbance after adding 75 mL of ferric nitrilo-triacetate to 1.500 mL of Apo transferrin was 0.222. Find the corrected absorbance.

Short answer

The corrected absorbance is$\approx 0.293$

Step-by-step solution

Find corrected absorbance:

$\mathrm{Corrected}\mathrm{absorbance}=\left(\frac{\mathrm{Total}\mathrm{volume}}{\mathrm{Initial}\mathrm{volume}}\right)(\mathrm{Observed}\mathrm{absorbance})$

To find total volume,

$\mathrm{Total}\mathrm{volume}\mathrm{of}\mathrm{solution}=\mathrm{Volume}\mathrm{of}\mathrm{EDTA}+\mathrm{Volume}\mathrm{of}\mathrm{drinking}\mathrm{water}$

Given,

$\mathrm{Volume}\mathrm{of}\mathrm{EDTA}=8.94\mathrm{mL}$

volume of drinking water = $5.00\mathrm{mL}$

Substitute in above equation,

Total volume of solution = $8.94\mathrm{mL}+5.00\mathrm{mL}$

$\mathrm{Total}\mathrm{volume}\mathrm{of}\mathrm{solution}=13.94\mathrm{mL}$

$\mathrm{Corrected}\mathrm{absorbance}=\left(\frac{\mathrm{Total}\mathrm{volume}}{\mathrm{Initial}\mathrm{volume}}\right)(\mathrm{Observed}\mathrm{absorbance})$

Consider,

Initial volume =$5.00\mathrm{mL}$

Total volume=$13.94\mathrm{mL}$

Observed absorbance =$0.105$

Substitute in above equation,

$\mathrm{Corrected}\mathrm{absorbance}=\left(\frac{13.94\mathrm{mL}}{5.00\mathrm{mL}}\right)\left(0.105\right)$

Corrected absorbance$\approx 0.293$