Answer to Question #90789 in General Chemistry for Lori Miller

Question

How do you find the concentration of your unknown substance from a set of data?

Answer 1

If a set of data is absorbance vs concentration, one may:

1. construct a calibration plot of concentration on x-axis and absorbance on y-axis using Excel;
2. find a best-fit straight line (click on any point of the plot and choose "add trendline") and extend the line to intersect;
3. display equation on the chart. This represent the equation of the plot. Now, one may substitute the y-value for the absorbance value of analyte in this equation to find a concentration.