Use the data table below to prepare a calibration curve (absorbance versus concentration in ppm). Fit the data to straight line and find the equation for the straight line and the R2 value. (Hint: Think about what to do with the absorbance of the blank.)

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ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
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Chapter1: Chemical Foundations
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The red color of soil is often due to the presence of iron. Metal ions are extracted from soil by stirring the soil in acid and then filtering the solution. One method for the analysis of Fe2+ is to form the highly colored Fe2+–thioglycolic acid complex. The complex absorbs strongly at 535 nm.

Calibration standards of 1.00, 2.00, 3.00, 4.00, and 5.00 ppm are prepared by transferring appropriate amounts of a 10.0 ppm working solution of Fe2+ into separate 50-mL volumetric flasks, each of which contains 5 mL of thioglycolic acid, 2 mL of 20% w/v ammonium citrate, and 5 mL of 0.22 M NH3. After diluting to volume and mixing, the absorbances of the standards are measured.

 

a)Use the data table below to prepare a calibration curve (absorbance versus concentration in ppm). Fit the data to straight line and find the equation for the straight line and the R2 value. (Hint: Think about what to do with the absorbance of the blank.) 

Absorbance
0.086
Blank
0.192
1.00 ppm
2.00 ppm
3.00 ppm
4.00 ppm
5.00 ppm
Soil Sample
0.284
0.388
0.480
0.595
0.345
Transcribed Image Text:Absorbance 0.086 Blank 0.192 1.00 ppm 2.00 ppm 3.00 ppm 4.00 ppm 5.00 ppm Soil Sample 0.284 0.388 0.480 0.595 0.345
Fe+ + CH2SH
CH;SH
00C +2H*
COOH
Thioglycolic acid
`HSH;C
ferrous thioglycolate
a) What color is the complex?
400 nm
500 nm
600 nm
700 nm
Transcribed Image Text:Fe+ + CH2SH CH;SH 00C +2H* COOH Thioglycolic acid `HSH;C ferrous thioglycolate a) What color is the complex? 400 nm 500 nm 600 nm 700 nm
Expert Solution
Step 1

The beer lambert's law is compared with line equation as follows:

A=mC+b      y=mx+cC=A-bmWhere,C is concentrationx-axis A is abosorbancey-axisb is interceptm is slope

 

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