Procedure

Apparatus:

Conductivity Meter, Physical Balance, Beaker, Glass Rod, etc.

Determination of Soil Conductivity:

a) Calibration of Instrument Using 0.01 N KCl Solution:

Dissolve 74.5 g KCl in 100 ml conductivity water free from CO₂. This is the standard reference solution whose conductance is 1412 µS/cm at 25°C.

Take this KCl solution in a 100 ml beaker; dip the electrode in it. If the conductivity meter does not read 1412 µS/cm, then adjust the instrument to read 1412.

b) Conductivity Measurement:

• Weigh 5 g of soil into a beaker and add 25 mL distilled water.
• Stir well for about 5–10 minutes and allow it to settle for some time.
• Transfer the distillate into another beaker for conductivity measurement.
• Thoroughly rinse the cell one or more times with the sample.
• Read the sample conductivity directly from the conductivity meter.

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 and check availability of all required chemicals and reagents.
• Prepare reagents if not available using appropriate components.
• Adjust the Bunsen burner to a proper flame – a small blue cone.
• Clean all apparatus with chromic acid and distilled water. Ensure they are free from water droplets.
• Calibrate the electronic weighing balance before taking measurements.
• Ensure the desiccator contains sufficient desiccant like silica gel.
• Clean the crucible with chromic acid, heat it, cool it, and handle only with clean tongs or tissue paper (never by hand).
• Switch on the oven and set the temperature to 130°C. Use cotton gloves when working with the oven.
• Clean the Kipp's apparatus tube with water. Ensure it contains enough iron sulfide and H₂SO₄ to produce H₂S gas.
• Clean all glassware with soap and distilled water. Recap reagent bottles after use.
• Switch off lights, exhaust fan, oven, and gas cylinder before leaving the lab.
• Discard used gloves in the designated waste bin.