Conductivity

Conductivity refers to the process through which energy is transferred via contact with materials. Conductivity is of various types; however, the primary three are electrical, thermal, and ionic conductivity. Any material can either be an insulator or a good conductor.

Various materials possess conductivity of different degrees. Different types of energy being transferred also determine the unit of measuring conductivity. If we take the example of electrical conductivity, it gets measured in siemens per metre.

Several factors determine the degree of conductivity. They are – temperature, material composition, structure, etc. The conductivity of any material tells a lot about its uses and applications in real life. 

Different Types of Conductivity

Energy that can be conducted through a material can be of any form – electricity, sound energy, thermal energy, or ionic energy. These types of conductivities are explained as follows:

• Thermal conductivity: It’s the ability of a material to conduct heat (thermal) energy. Thermal energy is measured in W/mK or watts per metre-kelvin. Materials that possess good thermal conductivity, such as metals, transfer heat very well and release the heat quickly. They are thus often used in heat sinks. On the other hand, gases have low thermal conductivity and thus form a good insulator. 
• Hydraulic conductivity:  It measures how well water penetrates through a porous substance such as rock. One crucial application of hydraulic conductivity is within the study of hydrology and agriculture.
• Acoustic conductivity: Acoustic conductivity is the capacity of any material to propagate sound waves within its structure. Essentially waves of sound cannot travel in a vacuum, unlike electromagnetic waves; however, they require any medium such as air to travel. 
• Electrical conductivity: Polarised materials, as well as metals, are very good conductors of electricity. The SI unit for measuring electrical conductivity is SI unit siemens per metre. Those materials that are good conductors of electricity form an essential part of generating and transmitting electricity. Industries or households, as we know, are dependent on these materials, which are good conductors of electricity. Copper is one such metal that is an excellent conductor of electricity and is also cheaper and more abundant. 
• Ionic conductivity: It is quite similar to electrical conductivity, however, on a molecular level. Ionic conductivity is how the charge of particles or ions move across the molecular structure of any matter. Electrolytes are chemicals that allow ions through their crystalline or molecular structure. One crucial application of ionic conductivity can be seen in how batteries work.

These types of conductivity are important to us in the study of chemistry to analyse the behaviours of different materials under varied conditions. Take an example of measuring the ionic conductivity of any substance that can help researchers design better batteries with increased longevity. 

Determining Electrical Conductivity

When studying conductivity notes, it is also essential to understand the conductivity of different solutions. The conductivity of a solution depends upon and is directly proportional to the ions the solution contains. 

In order to determine conductivity, an electrical current is passed throughout a solution. Siemens per litre per mole is the measurement unit for determining electrical conductivity. 

Ionic Conductivity

Ionic conductivity means the tendency of the ions of a substance to move from one side to the other when in an aqueous solution. Some of the substances like ions essentially do not conduct any form of electricity when in a solid state. However, when they dissociate in an aqueous solution, their ions start moving freely, thereby conducting electricity. Some of the important applications of ionic conductivity include building materials to insulate buildings from heat, checking the purity of metals like silver and copper. 

Thermal Conductivity

Essentially conductivity requires a medium that is solid. So, we can define thermal conductivity as the rate through which thermal energy can be transferred via a substance. It is generally measured as per the unit cross-sectional area of a substance. In order to allow the conduction of thermal energy, it is important for a temperature gradient to exist. 

It is important to note that thermal conductivity is significantly different from convection or radiation. As in the process of convection heat is essentially carried through a fluid, particularly gas or molten substance. Similarly, radiation also does not essentially require a medium and mainly propagates through electromagnetic waves.

Conductivity of Water

It is important to note that pure water is not a good conductor of electricity and essentially increases with the rise in ionic concentrations. The following are the purity of types of water and their conductivity:

1. Seawater: 5 S/m
2. The conductivity of Drinking Water: 0.005-0.05 S/m
3. Distilled Water Conductivity: 5.5 × 10-6 S/m

Conclusion

Hopefully, through the conductivity notes, you have been able to understand conductivity, the different types of conductivity, and how conductivity can be measured. It is important to understand the concept of conductivity as it is one of the most widely used phenomena that is applied in various industrial processes.