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 25oC.
- Take this KCl solution in a 100 ml beaker; the electrode was dipped in it. If the conductivity meter does not read 1412 µS/ cm, then adjust the instrument to read 1412.
b) Conductivity Measurement:
- 5 g of the soil is weighed into a beaker and to that add 25 mL distilled water.
- Stirred well for about 5-10 minutes and is allowed to settle for sometimes.
- The distillate is taken into another beaker and is used for conductivity measurements.
- 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 lab coat and gloves when you are in the lab. When you enter the lab, switch on the exhaust fan and make sure that all the chemicals and reagents required for the experiment are available. If it is not available, prepare the reagents using the components for reagent preparation.
- Properly adjust the flame of the Bunsen burner. The proper flame is a small blue cone; it is not a large plume, nor is it orange.
- Make sure to clean all your working apparatus with chromic acid and distilled water and ensure that all the apparatus are free from water droplets while performing the experiment.
- Make sure to calibrate the electronic weigh balance before taking the measurements.
- Ensure that the desiccator has sufficient amount of desiccant; Silica gel
- Use chromic acid to clean the crucible, then heat it and make sure to cool it and before placing in the desiccators. Ensure that you are handling the crucible, with cleaned tongs or with tissue paper .Never touch it with your hand.
- Switch on the oven and adjust the temperature to 1300 C. Make sure to use a cotton glove while working with a hot air oven.
- Make sure to clean the Kipp's apparatus tube with water and ensure that it has sufficient solid material; iron sulfinide and acid, H2SO4 for producing H2S gas.
- Clean all glass wares with soap and distilled water. Once the experiment completed recap the reagent bottles. Switch off the light, exhaust fan, hot air oven and Gas cylinder before leaving the lab.
- Discard the used gloves in a waste bin.