Page 48 - Practical book PC406-MNU-2025

MANSOURA NATIONAL UNIVERSIY
PHARM D- CLINICAL PHARMACY LEVEL II INSTRUNENTAL ANALYSIS (PC 406)

II- Colorimetric determination
of Potassium chromate

P Pr ri in nc ci ip pl le e

K2CrO4 (M.Wt.= 194.19 g) has a yellow color in aqueous solution, so can be

determined colorimetrically at max = 390 nm .

Stock concentration of K 2CrO 4 solution (standard solution) = 0.6 gm%.

Molecular weight of K2CrO4 = 194.19 gm.

P Pr ro oc ce ed du ur re e

1) Transfer 2.0, 4.0, 6.0, 8.0, 10.0 mL of stock solution and 10.0 mL of unknown

sample solution into 100-mL measuring flask (every student take only one

volume in his measuring flask).

2) Complete to the mark with water, shake well.

3) Measure the absorbance at 390 nm and draw the standard calibration curve

4) Measure (A) of unknown sample

5) Calculate the concentration of the unknown sample from previously plotted

calibration curve and calculate a, 1% , ε.
 cm 1

20 | P a g e S e c o n d s e m e s t e r 2 0 2 4 - 2 0 2 5