Question

What is the difference between electrochemical and electrolytic cell?

Short answer

Answer: Electrochemical cells, such as voltaic or galvanic cells, convert chemical energy into electrical energy through spontaneous redox reactions, while electrolytic cells use electrical energy to drive non-spontaneous redox reactions. In electrochemical cells, the redox reactions happen spontaneously and generate electric current, whereas in electrolytic cells, external energy input is required for the reactions to occur. A common example of an electrochemical cell is the Daniell Cell, which is used to power various electronic devices. An example of an electrolytic cell is the electrolysis of water, which is used for industrial processes and chemical synthesis, such as the extraction of metals and production of chemical compounds.

Step-by-step solution

Definition: Electrochemical Cell

Electrochemical cells, also known as voltaic or galvanic cells, are devices that convert chemical energy into electrical energy through spontaneous redox (reduction-oxidation) reactions. They consist of two electrodes (anode and cathode) which are submerged in an electrolyte solution and connected externally through a wire. In these cells, the chemical reactions occur between the electrolyte and the electrodes, producing a flow of electrons in the wire, generating electricity.

Definition: Electrolytic Cell

Electrolytic cells are devices that use electrical energy to drive non-spontaneous redox reactions. They also consist of two electrodes (anode and cathode) submerged in an electrolyte solution and connected to an external source of voltage (a battery or a power supply), which forces the redox reaction to occur. In these cells, an external source provides the electrical energy required for the chemical reactions to take place.

Redox Reaction: Electrochemical Cell

In an electrochemical cell, the redox reactions happen spontaneously, meaning they generate energy and do not require an external source of electricity. The anode is the site of oxidation, where electrons are released, while the cathode is the site of reduction, where electrons are consumed. As the electrons flow from the anode to the cathode through the external wire, electric current is produced.

Redox Reaction: Electrolytic Cell

In an electrolytic cell, the redox reactions are non-spontaneous and require external energy input to occur. The anode is still the site of oxidation, while the cathode remains the site of reduction, but in this case, the electrons are forced to flow in the opposite direction by the external electric field provided by the battery or power supply. The application of external energy drives these reactions against their natural direction.

Example: Electrochemical Cell

One of the most common electrochemical cells is the standard Daniell Cell, which consists of a zinc (Zn) anode, a copper (Cu) cathode, and electrolyte solutions containing Zn^2+ and Cu^2+ ions. In this cell, the spontaneous redox reactions produce a flow of electrons from the zinc electrode to the copper electrode, generating electrical energy that can be used to power a circuit.

Example: Electrolytic Cell

A simple example of an electrolytic cell is the electrolysis of water. In this process, an electric current is applied to the water, causing it to dissociate into hydrogen (H2) and oxygen (O2) gases. The H2 gas is produced at the cathode, where water molecules are reduced, while the O2 gas is produced at the anode, where water molecules are oxidized.

Application: Electrochemical Cell

Electrochemical cells are used as primary and secondary batteries, fuel cells, and sensors. They generate electrical energy that can be used to power various electrical and electronic devices, such as mobile phones, laptops, electric vehicles, and many other applications.

Application: Electrolytic Cell

Electrolytic cells are used for various industrial processes and chemical synthesis, such as the extraction of metals from their ores, the production of chlorine gas and sodium hydroxide through the electrolysis of brine, and the electroplating of metals to give a protective coating or decorative finish.