Creating Solutions Of Standard Molarity

Name: Luis Paredes
Date: October 13, 2010
Creating Solutions of Standard Molarity
Purpose:
The purpose of this lab was to create a solution of the correct molarity, create a correlation chartbetween concentration and absorbance, and to learn how to operate a Spec 20 and use it to make
meaningful measurements.
Procedure:

Part 1 - Measuring the absorbance of standards
The Spec 20 wascalibrated by setting the 0% transmittance and 100% transmittance points
according to Appendix 3. A cuvette was filled with the 0.200 M standard solution of
CuSO4-5H2O, leaving at least 1 cm unfilledat the top of the cuvette. The maximum
absorbance wavelength (minimum % transmittance) was found for three wavelengths 580, 590, and 600 nm. The Spec 20 was set to the wavelength for maximumabsorbance. The
percent (%) transmittance for the 0.500 M, 0.200 M, and 0.100 M, and 0.050 M CuSO45H2O standard solutions were measured.
Part 2 - Measuring the concentration of solutions
20.0 mL of a 0.500M solution from solid CuS0 4-5H20 was created. After mixing the
w ater and the solid, the mixture w as transferred b ack and forth between the graduated
cylinder and a beaker to ensure that all ofthe crystals had dissolved. Once a
homogeneous solution was gotten, the percent transmittance of the sample in the Spec
20 was checked. F rom the s olution j ust created, 20.0 mL of a 0.200 MCuSO4-5H2O
solution was created. The percent transmission of the sample in the Spec 20 was checked
to ensure that the concentration was correct. This process was repeated to create 20.0 mL of
a 0.100 MCuSO4-5H2O solution, then 20.0 mL of a 0.050 M CuSO4-5H2O solution, and
confirm the concentrations using the Spec 20.
Part 3 - Deducing the concentration of a solution
A clean cuvette was filledwith the CuSO4-5H2O solution of unknown concentration. The
percent transmittance of this solution was measured and recorded .

Data/Calculations:

Part 1 - Measuring the absorbance of standards...