Atomic Absorption and Emission Spectroscopy
This lab can be done in parts!!
Absorbance is a unitless number
Make sure that you make GOOD observations and describe the colors that you see! Make sure
that all boxes are filled in! Does the substance sparkle when burning, is a lot of smoke given off??
These are things to comment on in the observation section!
You can and should use both ends of a Q-tip! Waste not!!
It’s pipet time! If you do NOT know how to use a pipet – ASK!! You are using a pipet incorrectly
if you are doing any or all of the following:
Liquid getting sucked up into the bulb
Liquid falling out of the bottom of the pipet as you are trying to quickly transfer it into
another container
Using the pipet bulb to squirt out the liquid like a firehose!!
Please ask! And please practice a few times with water before moving onto the colored (dye)
solutions!
Make sure that you obtain the dye where the concentration is KNOWN. You will not be able to
use a calibration plot from the unknown substance and will have to repeat the entire
dilution/calibration plot! The KNOWN dye is in the LARGER container!
In order to determine the concentrations of dye that you make, you will be performing a dilution.
The equation for the dilution is
C1V1 = C2V2
Where C1 = concentration of known dye
C2 is the concentration you are looking for (unknown – what you are
solving for!!!)
V1 = amount of concentrated dye you used
V2 = TOTAL volume (dye + water!!)
Please make sure that you plug your colorimeter into channel 1 (if it is not already done!) before
opening the program. Otherwise, LoggerPro does not recognize the apparatus. You should make
sure that Experiment 11 is open – go to File, open, Chemistry with Computers and find Expt 11!!
Start with the weakest concentration first and work up to the strongest concentration. Do rinse the
cuvette between uses. Make sure that the ribbed sides are where you hold the cuvette. Wipe off
your grimy fingerprints before inserting the cuvette into the colorimeter with Kimwipes. Make
sure the light source goes through the clear sides of the cuvettes, not the ribbed sides!
Make SURE for Question 1, Part D when you are asked to read the concentration off your plot –
you need to:
1.)
On your plot, using a pen, mark the concentration point that corresponds to your
unknown absorbance
If you make a mistake entering a concentration let the lab instructor or Karina know – we can help
fix that!!