The absorbance of several known concentrations of FeSCN^2+ were measured using a

Question

The absorbance of several known concentrations of FeSCN^2+ were measured using a spectrophotometer to determine the Beer's Law constant, C, from Eq. 3. These data can be found in Table 4 below. The calibration curve needs to pass through the origin, i.e., when the concentration of FeSCN^2+ is zero (0), the absorbance of that solution is also zero (0). Be sure to include this point in your graph as well. a. Use Excel to prepare a calibration curve for this data using Eq. 3: A = CM. In a graph of two variables, one is an independent variable while the other is the dependent variable. The dependent variable is always plotted on the y-axis while the independent variable is plotted on the x-axis. In this case, the absorbance depends on the concentration. A video lecture showing an example of creating a calibration curve in Excel is available by cutting and pasting the following URL into your browser: http//media.collegeanywhere.org/view/content/18553 b. Determine the slope of the best fitting line. The slope is equal to C. C = _____

Explanation / Answer

Since Absorbance,A= ebC, where C= concentation, e= molar extinction coefficient and b= path length

a plot of dependent variable(A) vs concentration ( independent variable) gives a straight line whose slope is eb.

The plot is shown below

the slope is 4500/M

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