POTENTIOMETRIC
REDOX TITRATION
BAUTISTA ,
Anne Judith
LARIN,
Michelle V.
OBJECTIVES
At the end of the experiment, the student should be able to:
1.Construct a potentiometric redox titration curve
2.Determine the % Fe in a sample by potentiometric redox titration
INTRODUCTION
Potentiometry
definition
indicator electrode
reference electrode
Potentiometric titration
applications
general procedure
similarities with redox titration
INTRODUCTION
Determining the endpoint from a potentiometric redox titration curve:
EXPERIMENTAL
Preparation of Cu/Cu2+ Reference Electrodes
5 cm Pasteur pipet: plugged
with cotton saturated KCl/KNO3,
0.1 M of CuSO4 solution
Copper wire voltmeter
Modelling clay
EXPERIMENTAL
Preparation of KMnO4
weight of KMnO4 = ?
300 mL of 0.01 M solution
Dissolve in 100 mL distilled water.
Dilute to reach 300 mL.
Store in a colored container.
EXPERIMENTAL
Standardization of KMnO4
0.3 g-0.4 g of Fe(NH4)2(SO4)2●6H2O
•100 mL beaker: 20 mL distilled water, 5 mL 2M H2SO4 voltmeter
2 mL increments of KMnO4 (Vtotal = 20 mL)
1 mL increments of KMnO4 (Vtotal = 30 mL)
Measure reduction potentials.
Repeat to make 3 trials.
EXPERIMENTAL
Standardization of KMnO4
10 mL unknown diluted: 100 mL
10 mL (diluted) + 5 mL of 2M H2SO4
2 mL increments of KMnO4 (Vtotal = 20 mL)
1 mL increments of KMnO4 (Vtotal = 30 mL)
Measure reduction potentials.
Repeat to make 3 trials.
RESULTS: TRIAL 1
RESULTS: TRIAL 1
RESULTS: TRIAL 1
RESULTS: TRIAL 1
RESULTS: TRIAL 2
RESULTS: TRIAL 2
RESULTS: TRIAL 2
RESULTS: TRIAL 2
RESULTS: TRIAL 3
RESULTS: TRIAL 3
RESULTS: TRIAL 3
RESULTS: TRIAL 3
DISCUSSION
Reference electrode, Eref
Salt bridge, Ej
Analyte solution and Indicator electrode, Eind
DISCUSSION
DISCUSSION
DISCUSSION
DISCUSSION
RECOMMENDATIONS
Voltmeter
CuSO4 solution
KMnO4