Determination of Electrical Conductivity of Water

laboratory technician at the work.

Introduction:

The importance of conductivity is related to the measure of the chemical or solids usually inorganic present in the water such as nitrate, phosphate, chloride, and sulphate ions being anionic and magnesium, sodium, calcium etc. Being cationic. The compounds such as phenol, sugar, alcohol, oil don’t conduct the electricity. This quality of water is highly affected by the changes in the atmosphere.

The geology of the prevalent area however also affects the conductivity residing with the abilities of water. The beds comprising of granite as the bed material have a lower rate of conductivity due to the presence of abundant inert elements in their reducing the conductivity rate.

The clayey based rivers have an increased conductivity rate due to the ionization property of its composition. The other surfaces which have the flow of the water are also based on the same principle of conductivity.

The water conductivity is based on the discharge capacity. The sewage system is highly conductive due to the presence of excess chlorides in the sample. Its unit of measurements are mho or Siemen.

Related theory:

The electrical conductivity of water is one of the most important parameter to determine the quality of the sample of water. This variates with the difference in the elevation along with the other factors. The one with the best quality is then kept as a standard for others or an indicator to determine the quality of the structure.

The electrical conductivity is defined as:

“Ratio of the electric field intensity to the current density of the sample being an opposite to the resistivity of the sample.”

S = J/e = 1/r

Sample Conductivity
Ultra-pure drinking water 5.5*10-6 S/m
Drinking water 0.005 – 0.05 S/m
Sea Water 5 S/m

 

This quality of the sample is determined by using a probe along with a meter. The probe is provided with the voltage to the two electrodes in it which is later immersed into the sample of water. This eventually causes a certain drop in the resistance of the sample resulting into a source to be used for the calculations of the conductivity rate of the sample.

It converts the values into the units of micromhos/cm for the declaration of the results. The meter with high precision and accuracy however adopted is highly cost effective being 350$ able to determine the samples accuracy its potentials and other credentials precisely.

This however can be determined in the labs by the virtue of the sample already collected from the field if the provision of lab testing is not kept mandatory.

The field sample collection however is taken up with care. The sample is to be stored either in a glass bottle or a bottle of polyethylene washed in a detergent being phosphate-free followed by a proper rinsing through the water samples of both tap and distilled water. The packs prepared in factories i.e. Whirl-pack can also be adopted for the very use.

Diagram Description automatically generated

Standards:

The standard method that can be adopted for this method is #2510, APHA 1992.

Apparatus:

  • A jar for measuring
  • Conducting material
  • Magnetic stirrer
  • A standard flask
  • A beaker of 250 ml
  • A funnel
  • Tissue papers
  • A solution of kCl.
  • A sample of distilled water.

Procedure:

The following procedure is however adopted.

  1. The sample stored from the field in the laboratory is provided with the electricity for the generation of the electric current.
  2. The sample is now prepared of 0.1N solution of kCl.
  3. The field sample is now placed in the electrode setting as shown in the above picture.
  4. The knobs along with the other aspects are set as per the standards.
  5. The solution is than added up with the prepared solution to undergo the conductivity.
  6. The readings are than observed to determine the conductivity of the sample.
  7. The set of readings are adopted being 3 to have an accuracy level. The analysis is to be carried out within the 12 hours of the collection of the sample. It should be filtrated against a filter paper of 0.45micro placed at a temperature of 4

Observations:

Sample Temperature Conductivity (սmho)
#1 ——– ——–
#2 ——– ——–
#3 ——– ——–

Comments:

The results obtained are determined.

Table Description automatically generated

Precautions:

The following precautions are to be adopted.

  • The sample obtained from the field is to be kept in proper atmosphere along with the conditions as listed along with the standards mentioned.
  • The instruments adopted are to be properly cleaned and obtained along the considerable instructions provided.
  • The setup provided is maintained at its best.
  • The other parameters such as salinity or TDS can be determined later but the conductivity is to be dealt with high precision and care.
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