(REVISED - This question is in reference to an experiment entitled Colorimetric
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(REVISED - This question is in reference to an experiment entitled Colorimetric determination of an equilibrium constant in aqueous solution. The following curves were obtained.······Concentration vs absorbances ofa solution to obtain its Molarity. It is referring to the sample (in liquid form) to be assayed that has been graphed). The solvent for an experiment was prepared by adding a volume of a stock solution (viagraduated pipette) to a 100 ml volumetric flask. The Solvent was added to a “mark" to make it up to a 100ml of the solution. Next, considering all the data generated data (See graphs below). The first six (6) points were graphed on an expanded scale. If it is decided to reject the first 3 data points. Will it be ok to remove these first 3 data points when considering the experiment? Please provide justification/s in removing these data set points from the entire data set based on the method used to prepare the solution? Least Squares Fit of all the data 16points y N 0.0472x + 0.026 R1 9769 8.00 Massaged Data A 1200 y 0.058x-0.0353 n°·0.9959 o .800 b 0.600 0.200 0.00 Data Collected ? ? ? Plot of ALL DATA XI UMA 0.15 0.28 0.55-1-0040 1.34 | 0.046 ? 2.05 0.068 2.56 | 0.103 191 4.10 | 0.167 0.030E Chart Area 0.800 4.50 0.270 6500.347 9.80 13.86 0.800 17.00 0.959 10.00 15.00 20,00 25.00 0.00 1.100 200 1.250 27.00Explanation / Answer
The experiment based on colorimetric based on beers and lambert law, which give relation between absorbance and cocentration
A = ecl
where e= molar extinction coefficient
A= Absorbance
c= Concentration
l= path length of cuvette
So, based on above formula the graph between absorbance and concentration must pass through origin and a straight line, if some points are not matching on straight line we can delete them because there is error while making solution either you take more parent solution or add little solvents ,thats why your data deviates from straight line. It is not creating any problem we remove two/three points.
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