Determining the Concentration of a Solution: Beer's Law

Last week in chemistry we did a lab where we had to find the concentration of a solution. For this lab you will need the following materials:

1. Power Macintosh or Windows PC
2. Vernier Computer Interface
3. Logger Pro
4. Colorimeter
5. One Cuvette
6. Five test tubes
7. stirring rod
8. 30ml of 0.40 M NiSO4
9. 5ml of NiSO4 unknown solution( the concentration they have to find)
10. two 10ml pipets, pipet pump or pipet bulb
11. distilled water
12. test tube rack
13. two 100-ml beakers

To start follow the below procedure

1. add about 30ml of 0.40M NiSO4 stock solution to a 100-ml beaker
1. add about 30ml of distilled water to another 100-ml beaker
1. you might need more this is just to start off
2. label four test tubes 1-5 
1. in test tube one place 2ml of 0.40 M NiSO4
1. then put 8 ml of H2O in
2. in test tube two place 4ml of 0.40 M NiSO4
1. then put 6 ml of H2O in
3. in test tube three place 6ml of 0.40 M NiSO4
1. put 4 ml of H2O in
4. in test tube four place 8ml of 0.40 M NiSO4
1. then put 2 ml of H2O in
5. in test tube five place10ml of 0.40 M NiSO4
1. then put 0 ml of H2O in
3. Put all this data in a table:

1. Trial Number	0.40 M NiSO4 (mL)	Distilled H2O (mL)	Concentration (M)
   1	2	8	0.08
   2	4	6	0.16
   3	6	4	0.24
   4	8	2	0.32
   5	10	0	0.40

   
   
4. Once each tube has both the 0.40 M NiSO4 and water stir them each with a stirring rod
5. next connect the Colorimeter to you computer and open Exp Colorimeter in the experiment 11 folder of Chemistry with Computers. Te vertical axis should read the absorbance scaled from 0 to 0.6mol/L and a horizontal concentration axis from 0  to 0.5mol/L
6. Now you are ready to calibrate the Colorimeter
1. you need to fill the cuvette 3/4 full with distilled water
2. holding the cuvette by the upper edges, place it in the cuvette slot in the Colorimeter and slide the top shut
3. Now you are at the point where you are going to calibrate the Colorimeter
1. choose calibrate from the experiment menue and the click Perform No
2. turn the wavelength knob on the Colorimeter to the 0%T position
3. then type zero in the edit box
4. when the display voltage reading for Input 1 stabilizes click keep
4. Part two 
1. turn the knob of the Colorimeter to the Red LED position (635 nm)
2. type 100 in the edit box
3. when the display voltage reading for Input 1 stabilizes click keep then click ok
7. Now we are going to collect the absorbance data for the five standard solutions
1. click collect and then take out the cuvette and dump out the water
2. take the solution from test tube one and pur it into the cuvette until it is nearly full
3. place it back in the Colorimeter and shut the lid
4. wait for the absorbance value to display on the screen then click keep
1. your data should be shown on a graph
1. repeat steps 2 through 4 on the remaining test tubes
2. you should also make a chart of the data you are collecting, since the data is already there i'll show you the table
1. Unknown absorbance will be different then the one I have down
1. make sure to so the first five before you do the unknown

2. Trial	Concentration (mol/L)	Absorbance
   1	0.080	0.186
   2	0.16	0.255
   3	0.24	0.511
   4	0.32	0.595
   5	0.40	0.726
   6	Unknown	0.45

   
   
3. Since the unknown solution in my class was different the results will be different, heres my graph

1. Trial	Concentration (mol/L)	Absorbance
   1	0.080	0.186
   2	0.16	0.255
   3	0.24	0.511
   4	0.32	0.595
   5	0.40	0.726
   6	Unknown	0.45

   Concentration of Unknown

   0.23 mol/L

   
   
5. Now using the absorbance level locate the level of concentration of the unknown using the graph.
6. Once you have figured out the unknown solution the lab is done make sure to properly discard the solutions and clean the test tubes.