he below information is to be used in answering the remaining Questions. Using d
ID: 568743 • Letter: H
Question
he below information is to be used in answering the remaining Questions. Using different volumes of a 37.7 mg L-1 iron stock solution, a series of ferrous ion complexes were made Each solution was diluled to firal volume of 100 0 rnL The absorption of each of these solutions was measured and the resulting data is reported below 16 8.4 0.686 9.65 Ploting this data and fiting to a Inear functon yekds a line with slope 0.227 L mg-1 and R2 0.994 Question 10 What is the concentration of iron in the unknown solution (betore it was diluted), in mg L 1.00 Enter a numenic answer only, do not include units with your answer 080 Enter Your Answer: 0.70 0.60 0.30 0.00Explanation / Answer
Using Beer's law ,
Absorbance=e*l*C
where e=absorptivity of species(Fe2+)
l=path length of light(1 cm)
C=concentration of species (in mg/L)=Cs*Vs/V
where Cs=concentration of stock,Vs=volume of stock used,V=total volume=100ml
Cs/V is constant ,so Abs=el (Cs/V)*Vs
Absorbance Vs Vs (as per given data) gives a linear plot of the form y=mx+c ,c=intercept=0,m=slope=el (Cs/V)
Also from the given callibration curve, slope=0.227 L/mg=el
from data table:
for,Vs=0.99ml
Abs=0.089=el (Cs/V)*Vs =(0.227 L/mg)*(Cs/100ml)*0.99ml
or,0.089=(0.227 L/mg)*(Cs/100ml)*0.99ml
Cs=39.603 mg/L
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