CHM 111 Solutions and Spectrophotometry

Revised 11/29/17 Name ________________________________ Station # ____ Date _________________ CHM 111 Solutions and Spectrophotometry Report Sheet PROCEDURE A: Mass of CuSO4 .5 H2O needed ____6.25g________ Show calculation: 0.05M*0.050L=0.0025*250g/mole= 6.25g PROCEDURE B: Table I Flask # Cuvette #1 Flask #2 Flask #3 Flask #4 Flask #5 Volume of 0.50 M CuSO4 stock solution (mL) 10.0 Volume of DI water (mL) 0.0 Molarity (M) 0.50 M 0.40 M 0.20 M 0.10 M 0.05 M PROCEDURE C: Table II Cuvette # Concentration Absorbance 1 0.50 M 1.351A 2 0.40 M 0.594A 3 0.20 M 0.127A 4 0.10 M 0.078A 5 0.05 M 0.073A 6 Unknown # 0.062A 7 Unknown # 0.060A 8 Blank (DI water) 0.504A Page 1 of 2 Revised 11/29/17 1. Check Beer’s Law by plotting absorbance vs molar concentration using Excel. 2. Is Beer’s Law valid for this system? Explain your answer. 3. If Beer’s Law is valid, the value of “E” should be constant. Use A = E*C*L or E = A/(E*L) and the data from Table II to calculate values of E for the five solutions below. The value of L is normally 1 cm so E = A/C in this experiment. Table III Solution # Calculated Values of E 1 2 3 4 5 Concentration of unknowns found from graph: Unknown # value _____________% error____________ Unknown # value concentration ______________ Absorbance value ____________ Reference concentration ______________ Absorbance value ____________ Reference _____________% error____________ Page 2 of 2