Procedure

Materials Required:

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

Reagents:

• 0.01, 0.02, 0.03, 0.04 and 0.05 mM Ascorbic acid standards
• 0.5 M acetate buffer
• 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 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 in the lab.
• Switch on the exhaust fan upon entering the lab.
• Ensure all required chemicals and reagents are available or prepare them as needed.
• Clean all apparatus with chromic acid and distilled water; ensure they are dry before use.
• Calibrate the electronic weighing balance before measurements.
• Ensure the spectrophotometer is functioning properly.
• Handle the cuvette using tissue paper only; never touch with bare hands.
• Wipe the cuvette before inserting it into the spectrophotometer.
• Clean all glassware after use and recap reagent bottles.
• Turn off lights and exhaust fan before leaving the lab.
• Discard used gloves in a waste bin.