electrode

Examples of electrode in the following topics:

• Electrolytic Properties

  • In other systems, the electrode reactions can involve electrode metal as well as electrolyte ions.
  • In batteries for example, two materials with different electron affinities are used as electrodes: outside the battery, electrons flow from one electrode to the other; inside, the circuit is closed by the electrolyte's ions.
  • Here, the electrode reactions convert chemical energy to electrical energy.
  • Neutral molecules can also react at either electrode.
  • The oxidized or reduced substances can also be the solvent (usually water) or electrodes.

• Voltaic Cells

  • Electrochemical cells have two conductive electrodes, called the anode and the cathode.
  • The anode is defined as the electrode where oxidation occurs.
  • The cathode is the electrode where reduction takes place.
  • The metal electrodes are immersed in electrolyte solutions.
  • During the reaction, the zinc electrode will be used and the metal will shrink in size, while the copper electrode will become larger due to the deposited Cu that is being produced.

• Predicting the Products of Electrolysis

  • Each electrode attracts ions that are of the opposite charge.
  • Neutral molecules can also react at either electrode.
  • The reaction at this electrode is:
  • This is why it appears that the copper has dissolved from the electrode.
  • The reaction at this electrode is:

• Electrolytic Cells

  • Electrolysis is the passage of a direct electric current through an ionic substance that is either molten or dissolved in a suitable solvent, resulting in chemical reactions at the electrodes and separation of the materials.
  • Two electrodes: an electrical conductor that provides the physical interface between the electrical circuit providing the energy and the electrolyte.
  • Electrodes of metal, graphite, and semiconductor material are widely used.
  • Choosing a suitable electrode depends on the chemical reactivity between the electrode and electrolyte, and the cost of manufacture.

• LCDs

  • Each pixel of an LCD consists of a layer of molecules aligned between two transparent electrodes and two polarizing films, and the actual liquid crystals are between these polarizing filters.
  • The electrodes are used to align the crystals in a particular direction, which produces the image seen on the screen.
  • When no electric field is being applied, the surface alignment directions at the electrodes are perpendicular to each other.
  • Polarizing filter film with a vertical axis to polarize light as it enters.Glass substrate with ITO electrodes.
  • The shapes of these electrodes will determine the shapes that will appear when the LCD is turned on.

• Free Energy and Cell Potential

  • Electricity is generated due to the electric potential difference between two electrodes.
  • In electrochemistry, the standard electrode potential, abbreviated E°, is the measure of the individual potential of a reversible electrode at standard state, which is with solutes at an effective concentration of 1 M, and gases at a pressure of 1 atm.
  • Since the standard electrode potentials are given in their ability to be reduced, the bigger the standard reduction potentials, the easier they are to be reduced; in other words, they are simply better oxidizing agents.
  • In the example of Zn2+, whose standard reduction potential is -0.76 V, it can be oxidized by any other electrode whose standard reduction potential is greater than -0.76 V and can be reduced by any electrode with standard reduction potential less than -0.76 V.

• Electrolysis of Water

  • For example, electrolysis of a solution of sulfuric acid or of a salt, such as NaNO3, results in the decomposition of water at both electrodes:
  • Hydrogen will appear at the cathode, the negatively charged electrode, where electrons enter the water, and oxygen will appear at the anode, the positively charged electrode.

• Chemical Assays, Radioisotopic Methods, and Microelectrodes

  • Three major types used for this purpose include chemical assays, radio isotopic methods and the use of micro electrodes.
  • Electrodes are characterized by a system of electrical conductors that are used to make contact with a non-metallic portion of a circuit.
  • In regards to microbiology and bacterial identification, micro-electrodes are commonly being utilized to identify pathogenic bacteria in numerous settings.
  • The micro-electrodes have the capability to function as bio-sensors and detect specific biological components of microbes.

• Electrolysis of Sodium Chloride

  • This results in chemical reactions at the electrodes and the separation of materials.
  • If sodium chloride is melted (above 801 °C), two electrodes are inserted into the melt, and an electric current is passed through the molten salt, then chemical reactions take place at the electrodes.
  • Metal ions receive electrons at the negative electrode, and the non-metals lose them at the positive electrode.

• Other Rechargeable Batteries

  • The electrolyte may serve as a simple buffer for internal ion flow between the electrodes, as in lithium-ion and nickel-cadmium cells, or it may be an active participant in the electrochemical reaction, as in lead-acid cells.
  • NiMH batteries use positive electrodes of nickel oxyhydroxide (NiOOH), as does the NiCd, but the negative electrodes use a hydrogen-absorbing alloy instead of cadmium.
  • The lithium-ion battery is a family of rechargeable batteries in which lithium ions move from the negative electrode to the positive electrode during discharge, and back when charging.
  • The negative electrode of a conventional lithium-ion cell is made from carbon.
  • The positive electrode is a metal oxide, and the electrolyte is a lithium salt in an organic solvent.