# Procedure as explain in the lab manual except the 5

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The red color can absorbed by spectrophotometer at 480 nm using a green filter. Procedure: As explain in the lab manual except the 5 ml of unknown is added to the first unknown tube with 1.5 ml of distilled water. Also, 6.5 ml of unknown added to the unknown tube with (0 ml) of distilled water. Results:
Tube # Absorbance at 480nm Conc. Of standard phosphorus (ppm) 0 0 0 1 0.133 5 2 0.206 10 3 0.328 15 4 0.395 20 5 0.483 25 Unknown 1 0.038 ?? Unknown 2 0.047 ?? Table1: the absorbance value for each conc. of standard iron. Calculation by using excel graph: 0 1 2 3 4 5 6 7 8 9 0 0.1 0.2 0.3 0.4 0.5 0.6 f(x) = 0.04 x absorbance vs. consentration of iton (ug/ml) conc. ug/ml absorbance at 480nm Solution # Calculation of conc. of unknown iron from equation y= 0.0201x
# 6 y= 0.0201x , x = y 0.0201 x = 0.038 0.0201 = 1.89 ug / ml #7 y= 0.0201x , x = y 0.0201 x = 0.047 0.0201 = 2.33 ug / ml The calculation of unknown # 6 in (mg/ml) 1.89ug/ml 1ml X 100ml, X= 1.89 x 100 = 189 ug/100ml 189 ug 1g X 30g, X = 5670 ug/30g 1mg 1000 ug X 5670 ug, X =5670/1000 ug , X= 5.67 mg The calculation of unknown # 7 in (mg/ml) 2.33ug/ml 1ml X 100ml, X= 2.33 x 100 = 233 ug/100ml 233 ug 1g X 30g, X = 6990 ug/30g 1mg 1000 ug X 6990 ug, X =6990/1000 ug , X= 6.99 mg
The average of iron conc. ¿ 5.67 + 6.99 2 = 12.66 2 = 6.33 mg / 30 g Calculation by using manual graph: