Results 1–7 of 7 for polučlanak
Half-cell is a part of galvanic cell in which oxidations or reduction of an element in contact with water or water solution one of its compounds.
Battery a device that converts chemical energy to electrical energy. The process underlying the operation of a battery involves a chemical reaction in which electrons are transferred from one chemical species to another. This process is carried out in two half-reactions, one that involves the loss of electrons and one that involves their gain. The battery is an electrochemical cell divided in two half-cells, and reaction proceeds when these are connected together by an electrically conducting pathway. The passage of electrons from one half-cell to the other corresponds to an electric current. Each half-cell contains an electrode in contact with the reacting species. The electrode which passes electrons into the circuit when battery discharges is called anode and is negative terminal. The electrode which receives electrons is called cathode, and is the battery’s positive terminal. The electrical circuit is completed by an electrolyte, an electrically conducting substance placed between the two electrodes which carriers a flow of charge between them. In wet cells, the electrolyte is a liquid containing dissolved ions, whose motion generates an electrical current; in dry cells the electrolyte is basely solid, for example, a solid with mobile ions or porous solid saturated with an ionic solution.
Electromotive force (e.m.f. or EMF) is the difference in electric potential that exists between two dissimilar electrodes immersed in the same electrolyte or otherwise connected by ionic conductors.
Negative pole is that half-cell in electrochemical cell that has the most negative electrode potential.
Positive pole is that half-cell in the electrochemical cell which has the most positive electrode potential.
Electrode potential is defined as the potential of a cell consisting of the electrode in question acting as a cathode and the standard hydrogen electrode acting as an anode. Reduction always takes place at the cathode, and oxidation at the anode. According to the IUPAC convention, the term electrode potential is reserved exclusively to describe half-reactions written as reductions. The sign of the half-cell in question determines the sign of an electrode potential when it is coupled to a standard hydrogen electrode.
Electrode potential is defined by measuring the potential relative to a standard hydrogen half cell
The convention is to designate the cell so that the oxidised form is written first. For example
The e.m.f. of this cell is
By convention, at p(H2) = 101325 Pa and a(H+) = 1.00, the potential of the standard hydrogen electrode is 0.000 V at all temperatures. As a consequence of this definition, any potential developed in a galvanic cell consisting of a standard hydrogen electrode and some other electrode is attributed entirely to the other electrode
Galvanic cell (voltaic cell) is a simple device with which chemical energy is converted into electrical energy. Galvanic cells consist of two separate compartments called half cells containing electrolyte solutions and electrodes that can be connected in a circuit. Two dissimilar metals (e.g., copper and zinc) are immersed in an electrolyte. If the metals are connected by an external circuit, one metal is reduced (i.e., gains electrons) while the other metal is oxidized (i.e., loses electrons).
In the example above, copper is reduced and zinc is oxidized. The difference in the oxidation potentials of the two metals provides the electric power of the cell.
A voltaic cell can be diagrammed using some simple symbols. In the diagram the electrodes are on the outer side of the diagram and a vertical line (|) is used to separate the electrode from the electrolyte solution found in the compartment. A double vertical line (||) is used to separate the cell compartments and is symbolic of the salt bridge. Usually in a diagram the species oxidized is written to the left of the double slash. Here is an example of the Daniell cell:
The names refer to the 18th-century Italian scientists Alessandro Volta (1745-1827) and Luigi Galvani (1737-1798).
Generalic, Eni. "Polučlanak." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
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