7/21/2019 ChemLab Prelab2.docx

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Pre-Lab #2

1) The purpose of this lab is to find out the concentration of a certain red allura dye in a

sample of Kool-Aid using a colorimeter.

2) Transmittance is the uantity of light transmitted onto a sample di!ided by the amount

of light that originally fell onto the surface. Absorbance is the negati!e logarithm of the

transmittance.

") eer-Lambert la$ is defined as A % e&l&c' $here e is a constant' l is path length' and c

is concentration.

() log*+.,+2) % +.1+"

) An absorption spectrum is a graph plotting of a samples absorbance at different

$a!elengths.

/) A calibration plot is a plot of absorbance !s. concentration for solutions $ith a 0no$n

concentration.

) ou prepare a blan0 by filling a cu!ette $ith distilled $ater. A standard solution is a

solution that has a 0no$n concentration of solute.

3) 12+++ 4-1 cm-1 & +.+++3 4 & 1cm % ,./