Procedure

Materials Required:

• Polarographic Instrument
• Beaker
• 10 mL Pipette
• Wash bottle
• 100 mL volumetric flask

Reagents:

• 1, 2, 3, 4 and 5 mM Cadmium standards
• 2 M KCl solution
• 0.2% gelatin solution
• Distilled water

Procedure:

1. Select the concentration from the list.
2. Click “Load Cadmium Sample” button.
3. Select “Scan Analysis”.
4. Click “Plot Graph”.
5. Select the unknown concentration from the concentration list.
6. Repeat steps 2, 3, and 4.
7. Enter the concentration values on the worksheet.
8. Plot the calibration curve by clicking the “Plot” button on the worksheet.
9. Calculate the unknown concentration value from the calibration curve.

Observations and Calculations:

No	Concentration (mM)	Diffusion Current (id) (µA)
1
2
3
4
5

Plot: Concentration vs Diffusion Current

id of unknown concentration = ...................... µA

Therefore, concentration of the given solution = ...................... mM

Result

Unknown concentration of the given solution = ...................... mM

Points to Remember While Performing the Experiment in a Real Laboratory

• Always wear a lab coat and gloves when you are in the lab.
• Switch on the exhaust fan before starting.
• Ensure all chemicals and reagents required for the experiment are available. If not, prepare them as needed.
• Clean all working apparatus with chromic acid and distilled water. Make sure they are dry before use.
• Calibrate the electronic weighing balance before taking measurements.
• Ensure the spectrophotometer is functioning correctly.
• Handle cuvettes using tissue paper only—never touch them with bare hands.
• Wipe the cuvette with tissue before inserting it into the spectrophotometer.
• Clean all glassware with soap and distilled water after use.
• Recap reagent bottles and switch off lights and exhaust fans before leaving the lab.
• Discard used gloves in the designated waste bin.