Question

Define (a) voltammograms, (b) hydrodynamic voltammetry, (c) Nernst diffusion layer, (d) mercury film electrode, (e) half-wave potential, and (f) voltammetric sensor.

Short answer

(a) A voltammogram is a graph or the plot of the current, expressed as a function of the applied potential.

(b) Hydrodynamic voltammetry is a type of voltammetry technique in which the solution containing the analyte flows with respect to the electrode being used for the purpose of measurement.

(c) Nernst diffusion layer is defined as a thin stationary layer of the solution, which is near to surface of the electrode.

(d) Mercury film electrode is a type of electrode in which there is a thin mercury film that is electro deposited on the inert electrode like glassy carbon.

(e) Half wave potential can be defined as the applied potential on a voltammetric wave on which the value of the current is half of the limiting current.

(f) The voltammetric sensor is a type of a voltammetric transducer that is selective for a particular type of species when it is covered with a membrane or porous material.

Step-by-step solution

Part (a) Step 1: Given Information

The definition of the voltammograms is to be stated.

Part (a) Step 2: Explanation

There are a variety of voltammetry methods available. These include linear sweep voltammetry, staircase voltammetry, alternating current voltammetry etc.

Voltammetry involves plotting the current against the applied potential.

A voltammogram is a curve expressing the current as a function of the applied potential.

This type of measurement is usually used to study the electrochemical properties of the analytes in the solutions or the molecules that have been adsorbed on the electrode.

Part (b) Step 1: Given Information

The definition of hydrodynamic voltammetry is to be stated.

Part (b) Step 2: Explanation

There are a variety of voltammetry methods available. These include linear sweep voltammetry, staircase voltammetry, alternating current voltammetry etc.

One such method is the hydrodynamic voltammetry. In this method, the solution is made to flow past the electrode. It is necessary to achieve a controlled mass transfer in order to obtain the desired results.

Part (c) Step 1: Given Information

The definition of Nernst diffusion layer is to be stated.

Part (c) Step 2: Explanation

The diffusion layer is an interface at which the concentration of the bulk keeps changing due to migration of the particles. Nernst diffusion layer is a thin stationary layer of the solution near to surface of the electrode.

The thickness of the diffusion layer can be decreased by the agitation. As the temperature rises, the thickness of the diffusion layer gets reduced.

Part (d) Step 1: Given Information

The definition of mercury film electrode is to be stated.

Part (d) Step 2: Explanation

Mercury film electrode is an electrode in which contains a thin mercury film, electro deposited on the inert electrode like glassy carbon.

These types of electrodes are generally used in the voltammetry measurements. Voltammetry refers to a type of measurement that is usually used to study the electrochemical properties of the analytes in the solutions or the molecules that have been adsorbed on the electrode.

Part (e) Step 1: Given Information

The definition of half wave potential is to be stated.

Part (e) Step 2: Explanation

At half wave potential, the polarographic wave current is equal to half of the diffusion current. For any given electrolyte, half wave potential is unique for each of the elements and for it’s different valence states and forms.

Part (f) Step 1: Given Information

The definition of voltammetric sensor is to be stated.

Part (f) Step 2: Explanation

Voltammetric sensors are also known as electrodes. The voltammetric sensors are usually employed for the analysis of various organic and inorganic analytes in various matrices.

It is a type of a voltammetric transducer that is selective for a particular type of species when it is covered with a membrane or porous material.