hydronium

(noun)

The hydrated hydrogen ion ( $H_3O^+$ ).

Related Terms

Examples of hydronium in the following topics:

  • The Leveling Effect

    • When a strong acid is dissolved in water, it reacts with it to form hydronium ion (H3O+) in the following reaction:
    • In reality, the pH of an aqueous solution containing HCl can only attain a value of -1.74, the pKa of hydronium ion, H3O+.
    • This value corresponds to every water molecule in water being converted to hydronium ion, and since water contains 55 moles per liter (water is 55M in water), 101.74 = 55, which would be 55M in hydronium ion.
    • As an interesting aside, the presence of hydronium ion itself often comes under question, particularly in dilute solution.
    • The presence of hydronium ion in dilute aqueous solution is unlikely.

  • Specialized Equilibrium Constants

    • In this process, one molecule of water donates a proton to a neighboring water molecule, which yields hydronium and hydroxide ions.
    • As described previously, hydrogen ions actually exist as solvated hydronium ions in aqueous solutions.
    • A water molecule is protonated to form a hydronium ion in the process.
    • A water molecule protonates a neighboring water molecule, yielding hydronium and hydroxide ions.

  • Acid-Base Properties of Water

    • The result is the formation of a hydroxide ion (OH-) and a hydronium ion (H3O+).
    • The self-ionization of water produces hydronium and hydroxide ions in solution.
    • Explanation of self-ionization of water and the formation of hydronium and hydroxide ions.

  • Strong Acids

    • More precisely, the acid must be stronger in aqueous solution than a hydronium ion (H+), so strong acids have a pKa < -1.74.
    • This generally means that in aqueous solution at standard temperature and pressure, the concentration of hydronium ions is equal to the concentration of strong acid introduced to the solution.
    • Due to the complete dissociation of strong acids in aqueous solution, the concentration of hydronium ions in the water is equal to the total concentration (ionized and un-ionized) of the acid introduced to solution:

  • Microbial Growth at Low or High pH

    • To survive, alkaliphiles maintain a relatively low alkaline level of about 8 pH inside their cells by constantly pumping hydrogen ions in the form of hydronium ions (H3O+) across their cell membranes and into their cytoplasm.

  • Strong Acid-Weak Base Titrations

    • This is due to the production of a conjugate acid during the titration; it will react with water to produce hydronium (H3O+) ions.

  • pOH and Other p Scales

    • Visualize the relative number of hydroxide ions and hydronium ions in solution.

  • The Brønsted-Lowry Definition of Acids and Bases

    • The products include the acetate ion, which is the conjugate base formed in the reaction, as well as hydronium ion, which is the conjugate acid formed.

  • Brønsted Acids and Bases

    • The acetate ion CH3CO2- is the conjugate base of acetic acid, and the hydronium ion H3O+ is the conjugate acid of the base, water:

  • The Arrhenius Definition

    • This protonation of water yields the hydronium ion (H3O+); in modern times, H+ is used as a shorthand for H3O+ because it is now known that a bare proton (H+) does not exist as a free species in aqueous solution.