Daniell cell

Introduction 

When a phone is hooked to its charger, how does the battery work? How does the cell in a TV remote control work? All of these questions have been thoroughly explored in the scientific discipline of electrochemistry. Electrochemistry is the study of both the creation of electricity through chemical processes and the use of electricity to conduct non-spontaneous chemical reactions. The task is accomplished by using cells. Cells are the building blocks that trigger chemical processes that produce or generate electricity.

Types of cells

There are two types of cells:

  1. Electrochemical cell: An electrochemical cell is a device that may produce electricity through chemical processes that occur naturally. The chemical reactions occurring here are called redox reactions. During redox reactions, electrons are exchanged between different chemical species. Galvanic or voltaic cells are other names for these devices. One type of electrochemical cell is the Daniell cell.
  2. Electrolytic cell: Electrolytic cells are a subset of electrochemical cells that are capable of using electrical energy to catalyse chemical processes. That is to say; electricity needs to come from somewhere else. Then, an artificial reaction can be initiated. Electrolytic cells have traditionally been used for the electrolysis of substances.

Difference between electrochemical cells and electrolytic cells

Cell structure 

There are two electrodes in a cell: the cathode (positive) and the anode (negative) (-ve terminal). Submerge both electrodes in the corresponding metal salt solutions. The anode of an electrochemical cell is also known as the oxidation half-cell because of the chemical process that takes place there. The cathode is the decreased half-cell, another name for it. Connecting the two electrodes is a salt bridge, a U-shaped tube filled with gel and an electrolyte.

Daniell cell

Daniel Cell Diagram

What is a Daniell cell?

An electrochemical cell known as a Daniell cell is used to transform chemical energy into electrical power. The cell undergoes a number of chemical processes in order to produce electricity. Electrodes made of zinc (Zn) and copper (Cu) are used as the anode and cathode in a Daniell cell. The salt solutions have been poured over the metals.

In a Daniell Cell, the anode is composed of zinc (Zn), while the cathode is composed of copper (Cu). There is still a chemical solution containing ions bathing both electrodes. The proper chemicals are copper sulphate and zinc sulphate. It improves the voltaic cell, using its copper and zinc electrodes to produce a 1.1 V potential difference. The cell supplies energy to the circuit after electrons are produced at the anode and transferred to the cathode.

Daniell cell chemical reaction 

The following chemical reactions take place in Daniell cell:

\(Zn\left( s \right) + C{u^{2 + }}\left( {aq} \right) \to Z{n^{2 + }}\left( {aq} \right) + Cu\left( s \right)\)

Reaction at the anode:

\(Zn\left( s \right) \to Z{n^{2 + {\rm{ }}}}\left( {aq} \right) + 2{e^ – }\;\;\;\)

Reaction at the cathode:

\(C{u^{2 + }} + 2{e^ – } \to Cu\left( s \right)\;\;\;\)

Daniell cell working 

In the Daniell Cell, \(CuS{O_4}\) and \({H_2}S{O_4}\)are stored in a copper container until needed. The components of its operating system are:

  • A zinc rod that has crystallised in the zinc sulphate solution may be seen (\(Z{n_2}S{O_4}\)).
  • A see-through layer underneath the copper container keeps the \(CuS{{O}_{4}}\) crystals and solution in touch. As a consequence, solution saturation is maintained.
  • An electric current is produced by the external circuit.
  • Mass is gained by the copper rod and lost by the zinc rod.
  • Zinc sulphate concentration rises as Copper sulphate decreases.
  • Both methods maintain their electrical neutrality.

Daniell cell representation 

The Daneil cell is represented as:

\(Zn{\rm{ }}\left| {{\rm{ }}Z{n^{2 + }}\left( {aq} \right){\rm{ }}} \right|{\rm{ }}\left| {{\rm{ }}C{u^{2 + }}\left( {aq} \right){\rm{ }}} \right|{\rm{ }}Cu\)

The symbol “| |” represent the salt bridge, the right side represents the reduction half-cell, and the left side refers to the oxidation half-cell.   

Application of Daniell cell 

Some of the applications of daniel’s cell are: 

  • Used for making batteries, which are essentially just groups of cells in series.
  • Creating electricity while minimizing electrical consumption.
  • Telepathy through inductive coupling

Summary 

Certain electrochemical cells function in an electrolytic fashion. Hence, the electrolytic cell has everything that would normally be present in an electrochemical cell. Both electrochemical and electrolytic cells rely on the transport of electrons throughout the system to carry out their functions. Whereas electrolytic cells undergo non-spontaneous chemical reactions, electrochemical cells undergo chemical reactions of their own accord. To put it another way, an electrochemical cell is not the same as an electrolytic cell.

 

Frequently Asked Questions

1. What is a rechargeable cell?

Rechargeable batteries can only be made from secondary cells, which undergo reversible chemical processes. a cell that generates an electrical current, but whose chemical activity may be reversed by delivering a current in the opposite direction through the cell.

2. What maintains the electrical neutrality in a cell?

The Salt Bridge is responsible for preserving charge neutrality in the Daniell cell’s two compartments.  It is a glass tube which  contributes to keeping the balance of the charge.

3. Why are the charges of electrodes different in Daniel cell?

Daniel cell is an electrochemical cell whose anode has a negative potential with the solution. Which makes it negatively charged. The removal of the metals from the anode during oxidation causes a buildup of electrons upon that anode, which gradually turns it negative. Eliminating metal ions from the electrolyte results in the consumption of electrons, which turns the cathode positive.

Electrochemical Cell

Introduction

How does a mobile phone’s battery charge when plugged into its charger, or how does the cell in a TV remote control work? All of these questions have answers in the scientific field of electrochemistry. Electrochemistry is the study of both the use of electricity to conduct non-spontaneous chemical reactions and the production of electricity through chemical reactions. To achieve the goal, cells are used. Cells are components that initiate chemical reactions that produce or generate electricity.

What is an electrochemical reaction?

An electrochemical reaction is any process that is initiated or accompanied by the flow of electrical current, and typically involves the transport of electrons between two substances—one solid and one liquid. An electrochemical reaction occurs when a solid electrode and a material, such as an electrolyte, interact. This flow causes the reaction to release or absorb heat by producing an electric current to pass across the electrodes. When, for example, two electrodes in contact with one another initiate an oxidation and reduction (redox) reaction, the oxidation number of all the atoms involved in the reaction changes.

The process of electrochemical reaction

The properties of the negatively charged\(\;{e^ – }\)determine how matter interacts with an electric current as it flows through a system. Because protons are positively charged matter units found in elements, groups of atoms, or molecules, the electron, the fundamental unit of electricity, is drawn to them. This attraction is comparable to the chemical attraction that particles have for one another. Every chemical reaction changes the structure of an atom’s electrons, and the liberated electrons can either join with matter particles to form reductions or be ejected by them (oxidation). 

Faraday’s rules define the quantitative relationship between a free electron in a current flow and the atoms of a substance, where they cause a reaction. Electrochemical process components are also known as ionic conductors or electrolytes.

What is an Electrochemical cell?

An electrochemical cell is a system that can generate electrical energy from spontaneous chemical reactions. The chemical processes that occur during this process are known as redox reactions. During redox reactions, electrons are transferred between chemical species. They are also referred to as galvanic or voltaic cells. An electrochemical cell is illustrated by the Daniell cell.

The following are the essential components of an electrochemical cell:

  1. An electrolyte is a substance found between electrodes that, when dissolved in polar solvents such as water, produces freely flowing ions, resulting in an electrically conducting solution.
  2. Electrodes are solid electrical conductors that are used in electrochemical cells and are made of good conductors, such as metals.
  3. They are available in two varieties:
  4. The Cathode is the area of the cell where reduction takes place.
  5. The anode is the part of the cell where oxidation takes place.
  6. A salt bridge connects the oxidation and reduction halves of an electrochemical cell, completing the circuit. It is brimming with KCl and other saturated salt solutions. The bridge is required for the ions in the solution to flow between half-cells.

What are the different kinds of electrochemical cells?

There are two major kinds:

  1. Galvanic Cell / Voltaic Cell: Chemical energy is converted to electrical energy in these electrochemical cells.
  2. Electrolytic Cell: In these cells, electrical energy is converted to chemical energy.

Explain its operation

  • Working Principle

The fundamental operating principle of an electrochemical system is the transfer of\(\;{e^ – }\)produced by a redox reaction occurring in it, which results in an electric current.

  • Working Mechanism 

When the switch is turned on after an electrochemical cell has been fully assembled, the galvanometer of the external circuit deflects. The needle of the galvanometer moves in the direction of the beaker containing the copper sulphate solution. It indicates that the current has changed direction from the copper sulphate solution beaker to the zinc sulphate solution beaker. When the circuit is completed, a change occurs that causes zinc atoms in the zinc electrode to oxidise and Cu atoms in the copper rod to reduce. Zinc releases two electrons, which copper accepts via an external circuit.

In Daniell Cells, chemical energy is converted to electrical energy.

Full redox reaction: \(\;Zn{\rm{ }}\left( s \right){\rm{ }} + {\rm{ }}C{u^{2 + }}\left( {aq} \right){\rm{ }} \to {\rm{ }}Z{n^{2 + }}\left( {aq} \right) + Cu{\rm{ }}\left( s \right)\;\;\;\)

Some applications of Electrochemical Cell

  1. Many non-ferrous metals are electro-refined in metallurgy using electrolytic cells, yielding very pure metals such as Pb, Zn, Al, and Cu. 
  2. It is used to recover pure Na metal from molten NaCl by storing it in an electrolytic cell.
  3. Silver oxide batteries are used in hearing aids.
  4. Thermal batteries are used in Navy gadgets for military applications.

Applications of Electrochemistry

  1. Electrical batteries are created using the concept of cells. A battery is a device used in science and technology that stores chemical energy and provides electrical access to it.
    1. Applications in defence (thermal batteries)
    2. Digital cameras (Li batteries)
    3. Audio equipment (silver-oxide batteries)
  2. Electroplating is used for a variety of purposes, including the production of jewellery and the corrosion protection of certain metals.
  3. Electrochemistry is required in a variety of industries, including the chlor alkali industry.

Summary

Electrochemistry is a fascinating subject. Electrochemical reactions are important to comprehend because they have significant academic and practical implications. Understanding the responses allows us to better understand how everyday objects such as a battery or cell work. Chemical energy can be used to generate electrical energy in electrochemical cells, and electrical energy can be used to generate chemical energy.

Frequently Asked Questions 

1. What factors affect electrode potential?

Ans. The reduction potential refers to an electrode’s ability to accept electrons, whereas the oxidation potential refers to an electrode’s tendency to lose electrons. The potential of an electrode is determined by the temperature and metal ion concentration at its surface.

2. Can a zinc pot be used to store copper sulphate solution?

Ans. Copper has a lower reactivity than zinc. As a result, zinc can remove Cu from its salt solution. If the\(\;CuS{O_4}\) solution is kept in a zinc container, copper will be removed from the solution.

\[Zn + CuS{O_4} \to ZnS{O_4} + Cu\]

As a result, the copper sulphate solution cannot be stored in a zinc pot.

3. In the SI system, what is the emf measurement?

Ans. The energy contained in a battery per Coulomb of charge is known as the electromotive force, EMF has a SI unit of volts, which is equal to joules per coulomb.