Data: Code # unknown used: ____ Molarity of Cu^2+ Absorbance readings: in primar
ID: 516959 • Letter: D
Question
Data: Code # unknown used: ____ Molarity of Cu^2+ Absorbance readings: in primary standard: ______ M _______ Standard a # 1:_______ M _______ Standard # 2: ______ M _______ Standard #3:______ M ______ Absorbance reading of the unknown Cu^2+ solution: ________ Analysis of data: Plot the above data on a piece of graph paper (manually-10 sq/inch paper) From the graph: the molarity of Cu^2+ in the unknown solution: ______ Questions Discuss some possible systematic and random errors which you may have encountered in this experiment. On the graph-find the slope "k". Show the setup on the graph paper. K = ______ Given that absorbance is proportional to the concentration (Molarity): A = k M What would be the absorbance of a 0.120 M solution of Cu^2+?Explanation / Answer
some of the possible errors
1. erros are possible during dilution of sample
2. If the reference sample contains some percentage of the sample to be measured, the straightline results may not be possible
Since Absorbance (A)= ebC, e= molar extinction coefficient , b= path length and C= concentration
Hence a plot of A vs C has to be straight line with slope of eb.( eb=K)
The plot is drawn and shown below
hence A= 12.01* concentration , Slope K= 12.01 /M
when A = 0.165, C =0.165/12.01=0.0137
when C=0.12M, A= 12.01*0.12=1.44
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