anode

(noun)

The electrode of an electrochemical cell at which oxidation occurs.

Related Terms

Examples of anode in the following topics:

  • Electrochemical Cell Notation

    • .), the anode, the cathode, and the electrode components are all described in this unique shorthand.
    • Recall that oxidation takes place at the anode and reduction takes place at the cathode.
    • When the anode and cathode are connected by a wire, electrons flow from anode to cathode.
    • The cadmium is oxidized by losing electrons, and solid Cd is the anode.
    • The anode half-cell is described first; the cathode half-cell follows.

  • 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 anode will undergo oxidation and the cathode will undergo reduction.
    • Copper readily oxidizes zinc; the anode is zinc and the cathode is copper.
    • Recall that reduction happens at the cathode and oxidation happens at the anode in a voltaic cell

  • Preventing Corrosion

    • This is because the exposed iron undergoes oxidation and is rendered anodic.
    • The sacrificial anode will corrode before the metal it is protecting does.
    • However, once the sacrificial anode corrodes, it must be replaced; otherwise, the metal it is protecting will begin to corrode as well.
    • Galvanic sacrificial anode attached to the hull of a ship; here, the sacrificial anode shows corrosion but the metal it is attached to does not.
    • The galvanic anode continues to corrode, consuming the anode material until eventually it must be replaced, but the cathodic material is protected.

  • Cathode Rays

    • Since the electrons have a negative charge, they are repelled by the cathode and attracted to the anode.
    • After the electrons reach the anode, they travel through the anode wire to the power supply and back to the cathode, so cathode rays carry electric current through the tube.
    • But at the anode (positive) end of the tube, the glass of the tube itself began to glow.
    • By the time the tube was dark, most of the electrons could travel in straight lines from the cathode to the anode end of the tube without a collision.
    • When they reached the anode end of the tube, they were traveling so fast that, although they were attracted to it, they often flew past the anode and struck the back wall of the tube.

  • Electrolytic Properties

    • Another reaction occurs at the anode, producing electrons that are eventually transferred to the cathode.
    • As a result, a negative charge cloud develops in the electrolyte around the cathode, and a positive charge develops around the anode.
    • Oxidation of ions or neutral molecules occurs at the anode, and the reduction of ions or neutral molecules occurs at the cathode.
    • Two mnemonics for remembering that reduction happens at the cathode and oxidation at the anode are: "Red Cat" (reduction - cathode) and "An Ox" (anode - oxidation).
    • It is possible to oxidize ferrous ions to ferric ions at the anode.

  • The Lithium-Ion Battery

    • The three participants in the electrochemical reactions in a lithium-ion battery are the anode, the cathode, and the electrolyte.
    • Both the anode, which is a lithium-containing compound, and the cathode, which is a carbon-containing compound, are materials into which lithium ions can migrate.
    • When a lithium-based cell is discharging, the positive lithium ion is extracted from the cathode and inserted into the anode, releasing stored energy in the process.
    • The anode is generally one of three materials: a layered oxide (such as lithium cobalt oxide), a polyanion (such as lithium iron phosphate), or a spinel (such as lithium manganese oxide).
    • In a lithium-ion battery, the lithium ions are transported to and from the cathode or anode.

  • X-Ray Spectra: Origins, Diffraction by Crystals, and Importance

    • In a previous Atom on X-rays, we have seen that there are two processes by which x-rays are produced in the anode of an x-ray tube.
    • The second process is atomic in nature and produces characteristic x-rays, so called because they are characteristic of the anode material.
    • X-ray spectrum obtained when energetic electrons strike a material, such as in the anode of a CRT.
    • The smooth part of the spectrum is bremsstrahlung radiation, while the peaks are characteristic of the anode material.
    • A different anode material would have characteristic x-ray peaks at different frequencies.

  • Electrolysis of Sodium Chloride

    • Chloride ions migrate the other way, toward the anode.
    • They give up their electrons to the anode and are oxidized to chlorine gas:
    • Chlorine gas bubbles out of the melt above the anode.
    • At the anode (A), chloride (Cl-) is oxidized to chlorine.

  • The Battery

    • One half-cell includes electrolyte and the anode, or negative electrode; the other half-cell includes electrolyte and the cathode, or positive electrode.
    • In the redox (reduction-oxidation) reaction that powers the battery, cations are reduced (electrons are added) at the cathode, while anions are oxidized (electrons are removed) at the anode.
    • When a battery is connected to a circuit, the electrons from the anode travel through the circuit toward the cathode in a direct circuit.
    • Notice the positive cathode and negative anode.

  • Predicting the Products of Electrolysis

    • Positively charged ions, or cations, move toward the electron-providing cathode, which is negative; negatively charged ions, or anions, move toward the positive anode.
    • You may have noticed that this is the opposite of a galvanic cell, where the anode is negative and the cathode is positive.
    • Oxidation of ions or neutral molecules occurs at the anode, and reduction of ions or neutral molecules occurs at the cathode.
    • For example, it is possible to oxidize ferrous ions to ferric ions at the anode:
    • At the positive anode, copper metal is oxidized to form Cu2+ ions.