Variations of Molar Conductivity with Concentration

Specific conductivity, also known as conductivity of an electrolytic solution at any given concentration, is the conductance of a unit volume of solution held between two platinum electrodes having a unit area of cross-section and separated by a unit length. Conductivity of a solution reduces with dilution because the amount of ions per unit volume that carry the current in a solution decreases with dilution. kappa is the symbol for it (k). The unit of conductivity is denoted by the following symbol:

k = siemen x m^-1

some of the variables that influence conductivity:

It is an extremely sensitive physical quantity that can be altered by a variety of circumstances…. The following are some of these considerations.

• Electrolyte’s chemical makeup
• The ion’s mass is measured in millimetres.
• The strength of the solution’s concentration.
• Temperature
• The solvent’s chemical make-up

Molar conductivity

Molar Conductivity is a measure of how well a substance conducts electricity or water.

The molar conductivity of a solution at a particular concentration is defined as the conductance of volume V of a solution containing one mole of electrolyte held between two electrodes with an area of cross-section A and a distance of unit length.

Molar conductivity = ⋀m = k/c 

Where,

⋀m = molar conductivity 

c =  Specific conductivity

C = concentration in moles per volume

 Molar conductivity can be calculated using the equation 

⋀m (S cm2 mol-1) = k(S/cm)×1000/molarity(mol/L)

Variation in the conductivity of molar solution

The molar conductivity of a solution containing one mole of electrolyte increases as the total volume, V, of the solution grows, while the molar conductivity decreases with decreasing concentration. As a result of dilution, the concentration decreases. When the concentration of a solution hits zero, the molar conductivity of the solution is referred to as the limiting molar conductivity of that solution. Molecular conductivity fluctuations with concentration differ between solid and weak electrolytes.

Variation of Molar Conductivity Changes as a Function of Concentration

Electrolytes employed in the experiment have different molar conductivities, which can be measured. In greater detail, the following variations are addressed below:

1. Electrolyte with a high concentration

Diluting strong electrolytes results in a reduction in molar conductivity. The following equation can be used to represent this decrease:

⋀m = ⋀m⁰ – Ac^1/2

By plotting a straight line from A to ⋀m, we obtain an intercept equal to the limiting molar conductivity (⋀m), a slope equal to -A, and an intercept equal to ⋀m. During the dissociation of an electrolyte in a solution, the value of A is determined by the charges on both the cation and anion that are produced.

Consequently, either the graph or the Kohlrausch law can be used to get the value of the limiting molar conductivity.

When it comes to electrolytes, Kohlrausch’s law of independently migrating ions states that the limiting molar conductivity is expressed as a sum of the amounts of cation and anion present.

⋀m⁰ = ⋀⁰cation+ ⋀⁰anion is a mathematical equation.

2. Electrolyte with a Low Sodium Concentration

Weak electrolytes, on the other hand, exhibit a linear increase in molar conductivity with increasing concentration. This is due to the decreased degree of dissociation that occurs in such electrolytes when they are present in concentrated solution.

The basic conductivity of a solution is well understood to increase as the electrolyte content in the solution grows. In a unit volume of a solution, the specific conductivity is determined by the amount of ions present. It is possible to increase the quantity of current-carrying ions in the solution by increasing the dissociation with dilution. While dilution increases the number of ions in a unit volume of solution, it decreases the number of ions present in a unit volume of the solution. As a result of this, the conductivity is reduced.

Conclusion

The presence of free ions in electrolytes leads them to conduct electricity. It’s similar to the way free electrons promote the conduction of electricity in metallic conductors, which is equivalent. When it comes to electrolytic conduction, the Arrhenius equation or principle is used to describe it.

We’re all aware of electrolytic solutions, which are created by dissolving a variety of salts in a solution. It is not necessary for the salts to be ionic all of the time. The only prerequisite is that the compound be composed of ions with diametrically opposed charges.

After dissolving an electrolyte in water, the Arrhenius principle states that the electrolyte molecules will be separated into two distinct charged ions, each with a different charge.

The charged particles have complete freedom to move about in the solution. Positive ions, also known as cations, may migrate towards a negative electrode, also known as a cathode, in order to lessen their own charge. Positive ions or anions will go toward the positive electrode or anode and oxidise themselves at the same time. Electric conduction is caused by the passage of charged particles across a fluid medium.