Beer’s Law Lab Conclusion Questions CALCULATIONS: 1. Calculate the concentration of each of your stock solutions (sol’n A) you made in Molarity (both CuSO4·5H2O and CoSO4·7H2O). 2. Calculate the concentration of each of the diluted solutions you made (sol’ns B, C, D) for both Cu and Co. 3. Plot a concentration (x) vs absorbance (y) calibration curve for both Cu and Co. You may put both on the same graph but label each line clearly. Different colors for the different solutions is suggested. You must use graph paper if doing manually or you can use Excel or other software to generate your graph. 4. Determine the slope and the equation for both lines. 5. Using the equations, calculate the concentration of the unknowns. Be sure to include the unknown number. CONCLUSIONS: 1. Why were the wavelengths of 800 nm for copper and 500 nm for cobalt used with the spectrophotometer? 2. Why did you have to make the standard solutions and determine their absorbance before determining the absorbance of the unknowns? 3. a) What are the three factors that affect absorbance? b) Which did you change in the experiment? c) How/why were the other two kept constant? 4. a) Why are some solutions colored? b) Can a spectrophotometer be used for colorless solutions such as an aqueous NaCl solution, to determine concentration? Why or why not.