The conductivity of water is a measure of the capability of water to pass electrical flow. This ability directly depends on the concentration of conductive ions in the water. These conductive ions originated due to inorganic materials such as chlorides, alkalis, carbonate and sulphide compounds and dissolved salts. In this article, let’s study the conductivity of water.
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What is Electrical Conductivity?
Electrical conductivity is nothing but the measure of the capability of the material to pass the flow of electric current. Electrical conductivity differs from one material to another depending on the ability to let the electricity flow through them. Protons, electrons, and neutrons present in the material carry the current. Protons carry a positive charge, and each electron carries a negative charge wherever it goes. The flow of electrons inside the material is referred to as the electric current.
Electrical conductivity is denoted by the Greek letter ρ.
The Electrical conductivity is the inverse of the resistivity and is given by
σ = 1/ρ
Where,
σ = electrical conductivity
ρ = resistivity
This ability of conductance in water is directly proportional to the concentration of the ions present in the water.
The Compounds which dissolve into the ions are known as the electrolytes. The more the number of ions present in the electrolyte, then the higher the conductivity of water. Similarly, the fewer ions present in water, the less conductive the conductivity of water. Deionized or distilled water can also act as an insulator due to the very low conductivity value. Seawater is said to possess a very high value of conductivity.
Pure water is said to be a bad conductor of electricity. Normal water is said to have impurities from ions called minerals etc. These ions are known to be responsible for the conduction of electric current in the water. Because the electrical current in water is transported by the ions present in them, the electrical conductivity is said to increase with the increase in the concentration of ions in them.
The conductivity of water is a measure of the capability of water to pass electrical flow. This ability directly depends on the concentration of conductive ions in the water. These conductive ions originated due to inorganic materials such as chlorides, alkalis, carbonate and sulphide compounds and dissolved salts.
What is Conductivity of Water?
The degree to which water conducts or transmits electricity or heat or sound in is called the conductivity of water.
Conductivity of Water Units:
The conductivity of water can be measured using multiple units. Some of them are:
| SI units | Siemens per meter [S/m] |
| U.S units | millimhos per centimeter [mmho/cm] |
Value:
The value of conductivity of water for various types of water is given below:
| Types of water | Conductivity Value |
| Pure distilled and Deionized water | 0.05 µS/cm |
| Seawater | 50 mS/cm |
| Drinking water | 200 to 800 µS/cm. |
| Rain or Snow water | 2 to 100 µS/cm |
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Salt Water Conductivity
Saltwater is a good conductor of electricity. Its conductivity is greater than normal water. This is because salt molecules contain sodium and chlorine ions (NaCl).
How is conductivity achieved?
Till now, we have learned that conductivity is purely the result of conductive ions present in the water. But how it actually conducts is the question. It can be simply explained by the following steps:
- The ions in the water conduct electricity because of their positive and negative charges.
- When the electrolytes tend to dissolve in the water, they get split into cation or positively charged and anions or negatively charged particles.
- As dissolved substances tend to split in the water, the concentrations of positive and negative charges remain the same.
This shows that, though the conductivity of the water increases with the addition of ions, it tends to remain electrically neutral.
What is Specific Conductance?
Specific conductance is the conductivity measurement made at 25° C. This is called the standardized method of achieving conductivity. As the temperature of the water affects the conductivity reading, reporting the conductivity at about 25° C allows the data to be compared easily. The Specific conductance is basically reported in uS/cm at about a temperature measuring 25° C.
If the measurement of electrical conductivity is accomplished at a temperature of 25° C, then it can be called the specific conductance. And, If the measurement is done at different temperatures and later corrected to the temperature of 25° C, then it is called the temperature coefficient.
Frequently Asked Questions – FAQs
How conductivity and salinity are related?
Conductivity is directly proportional to salinity. That is, when salinity increases, the conductivity will also increase.
How is temperature related to the conductivity of water?
When the temperature increases, the water’s conductivity will also increase.
What factors affect conductivity in the water?
The factors affecting the conductivity of water are-
How is the conductivity of water tested?
What is the conductivity of distilled water?
The distilled water conductivity is 0.05 µS/cm.
What is the conductivity of drinking water?
The drinking water conductivity is 200 to 800 µS/cm.
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