In: Chemistry
This is my lab and I am very confused regarding the calculations! It is supposes to demonstrate Le Chatelier’s principle.
After doing the following I need to calculate the molar absorbance for Co(H20)6 2+. The path length is 1cm and absorbance is .551. I got 5.51 L/mol *cm.
I also need to calculate the CoCl4 2- molar absorbance which I do not understand. The absorbance is .570 and the path length is 1cm. I do not know how to find the concentration.
1.Obtain a 10 mL graduated cylinder and three, 1 cm diameter spectrophotometer cells (cuvettes).
2. Fill one cuvette about ¾ full with deionized water. This cuvette will be used as the blank, to zero the instrument.
3. Fill a second cuvette about ¾ full with 0.10 M Co(NO3)2 .6H2O.
4. Prepare 100 mL of a 0.010 M Co(NO3)2 . 6H2O solution. Add exactly 10.0 mL of 0.10 M Co(NO3)2*6H2O to a 100 mL volumetric flask and dilute with deionized water to the mark.
5. Use the 10.0 ml graduated cylinder to prepare a solution of [CoCl4]2-. To the 10 mL graduated cylinder add 1.0 mL of 0.010 M Co(NO3)2 * 6H2O (prepared in step 4). Carefully pipette 4.0 mL of 12 M HCl into the graduated cylinder so that the total volume is 5 mL. Mix well.
6. Fill the third cuvette about ¾ full with the solution from step 5.
7. Obtain an equilibrium mixture from your instructor. This will be cuvette 4.