6. Standard addition was performed to determine the iron contained in Shiraz red wine from south central Australia using a flame-atomic absorption spectrometer. Absorbance (A.U.) Fe content in South Australian red wine 0.12 0.1 0.08 0.06 0.04 0.02 0 0 0.5 y = 0.0506x +0.013 R² = 0.9987 1 1.5 Concentration (ppm) 2 A) Calculate the concentration of iron in the red wine sample (in ppm). 2.5 B) How is the R2 value used in linear regression? What is an ideal R2 value? What does R² value tell you? C) Should the linear regression line in the above plot go through 0,0? Yes/No D) Why does the line not go through 0,0 on the standard addition plot? 3 E) The absorbance measurement was obtained three times for each sample and averaged by the instrument. Is the %RDS more likely to be higher when the actual concentration of the sample or standard being analyzed is low or high? Why?
6. Standard addition was performed to determine the iron contained in Shiraz red wine from south central Australia using a flame-atomic absorption spectrometer. Absorbance (A.U.) Fe content in South Australian red wine 0.12 0.1 0.08 0.06 0.04 0.02 0 0 0.5 y = 0.0506x +0.013 R² = 0.9987 1 1.5 Concentration (ppm) 2 A) Calculate the concentration of iron in the red wine sample (in ppm). 2.5 B) How is the R2 value used in linear regression? What is an ideal R2 value? What does R² value tell you? C) Should the linear regression line in the above plot go through 0,0? Yes/No D) Why does the line not go through 0,0 on the standard addition plot? 3 E) The absorbance measurement was obtained three times for each sample and averaged by the instrument. Is the %RDS more likely to be higher when the actual concentration of the sample or standard being analyzed is low or high? Why?
Chemistry
10th Edition
ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Chapter1: Chemical Foundations
Section: Chapter Questions
Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...
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Transcribed Image Text:6. Standard addition was performed to determine the iron contained in Shiraz red wine
from south central Australia using a flame-atomic absorption spectrometer.
Absorbance (A.U.)
Fe content in South Australian red
wine
0.12
0.1
0.08
0.06
0.04
0.02
0
0
0.5
y = 0.0506x+0.013
R² = 0.9987
1
1.5
Concentration (ppm)
2
A) Calculate the concentration of iron in the red wine sample (in ppm).
2.5
B) How is the R² value used in linear regression? What is an ideal R2 value? What does R²
value tell you?
C) Should the linear regression line in the above plot go through 0,0? Yes/No
D) Why does the line not go through 0,0 on the standard addition plot?
3
E) The absorbance measurement was obtained three times for each sample and averaged by the
instrument. Is the %RDS more likely to be higher when the actual concentration of the sample
or standard being analyzed is low or high? Why?
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, chemistry and related others by exploring similar questions and additional content below.![em1.png Part 3: Q9 Average absorbance Flask 8 Flask 9 Flask 10 1:1 Ratio so, Flask 11 Part 3: Q Flask 8 Flask 9 Flask 10 Flask 11 Part 3: Q10 Flask 8 Flask 9 Flask 10 Flask 11 Part 3 0.146 0.166 [Fe] -0.002mol/L 0.215 0.294 [FESCN³mol/L) 4.59% 10 5.18*10* 6.64*10* 9.08*10* [FXmol/L) 5.00 *10* 5.00*10* Y=3362x-0.0083 R² = 0.9993 5.00*10* 5.00*10* (Amounts of flask 8 (9 - 11's values are in the spreadsheet) 71% volume 5.00mL Molarity of Fe(NO3))3 = 0.2M Volume of Fe(NO3))3 = 5.00mL Moles of Fe³= Molarity x volume(L) Moles of Fe¹ = 0.2M X 0.005L = 1x10-³mole x [SCN][mol/ 4x10 5×10-4 7x10 1×10 1 Concentration of Fe³ = mole of Fe³ Volume mole of Fe³1x10³ mole G.O05L 8, Average absorbance for solution 8 (same for 9 - 11) Average absorbance for flask 8 = sum of all absorbances / number of readings (0.145 +0.147 +0.148) 3 Using equation of calibration curve's line(slope) of best fit, the average absorbances of the unknown concentrations to determine [FeSCN-Jat equilibrium in solution 8:…](/questions-and-answers/em1.png-...-part-3-q-average-absorbance-flask-and-11-ratio-so-flash-d-flask-10-flask-11-part-3-q-fla/c9657571-599f-4ed4-a5e6-fabcbd26b888){kind=link}
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