PASCO Spectrometer: Beer's Law

Learn how to use the PASCO Wireless Spectrometer and Spectrometry software to perform a Beer's Law analysis of the concentration of a colored solution.
After calibration and selection of wavelength, we establish the relationship between the absorbance and concentration for standard solutions and then determine the concentration of an unknown.
PASCO Wireless Spectrometer:
pasco.com/go?PS...
free Spectrometry software (Windows, Mac, iPad):
pasco.com/suppo...

[@bravesquid6183]

Can you only change the concentration after you find the absorbance?

[@pascoscientific]

The known concentrations of the reference solutions can be entered in the upper table before, during, or after their absorbances are measured. The unknown concentration in the lower table can be entered only after its absorbance is measured.

[@ailatolentino6481]

How did you determined the unknown concentration of 0.10 at the end and how did you solved for it? I

[@pascoscientific]

Given that the absorbance of the unknown was measured to be 0.18, you could determine its concentration either visually by looking at the graph or algebraically by solving the linear fit equation. Visually, follow a horizontal line with absorbance 0.18 from the y-axis until it intercepts the linear fit line; there, drop down to the x-axis to determine that the concentration must be about 0.1 M. Algebraically, the fit equation tells us that A = m*C + b, with the values of m and b provided in the fit box. Solve that equation for the concentration C, and then plug in the measured absorbance A of 0.18 to determine the concentration of the unknown.

[@user-rd1lu7yx1b]

did u do the black, with the white solution?

[@pascoscientific]

If you're referring to the calibration procedure that starts at 0:50, both the dark reference and light reference measurements are performed with the same cuvette containing the experiment's solvent, which is water in this case). Thanks for watching.

[@user-rd1lu7yx1b]

@@pascoscientific oh ok because at school we have a black cuvette to do the black