Brønsted-Lowry base

(noun)

any chemical species that acts as an acceptor of protons

Related Terms

Examples of Brønsted-Lowry base in the following topics:

  • The Brønsted-Lowry Definition of Acids and Bases

    • A Brønsted-Lowry acid is any species capable of donating a proton; a Brønsted-Lowry base is any species capable of accepting a proton.
    • The general scheme for a Brønsted-Lowry acid/base reaction can be visualized in the form:
    • Here, acetic acid acts as a Brønsted-Lowry acid, donating a proton to water, which acts as the Brønsted-Lowry base.
    • Here, ammonia is the Brønsted-Lowry base.
    • We first look at the Brønsted-Lowry theory, and then describe Lewis acids and bases according to the Lewis Theory

  • Brønsted Acids and Bases

    • A Brønsted acid is any species capable of donating a proton; a Brønsted base is any capable of accepting a proton.
    • In chemistry, the Brønsted-Lowry theory is an acid-base theory, independently proposed by Johannes Nicolaus Brønsted and Thomas Martin Lowry in 1923.
    • To that end, if a compound is to behave as an acid by donating a proton, there must be a base to accept that proton; the Brønsted-Lowry concept is therefore defined by the reaction:
    • The Brønsted-Lowry acid-base theory has several advantages over the Arrhenius theory.
    • Identify the Brønsted acid, Brønsted base, conjugate acid, and conjugate base in an acid-base reaction.

  • Weak Bases

    • A weak base is a chemical base that does not ionize fully in an aqueous solution.
    • As Brønsted-Lowry bases are proton acceptors, a weak base may also be defined as a chemical base with incomplete protonation.
    • A general formula for base behavior is as follows:
    • This results in a relatively low pH compared to that of strong bases.
    • The pH of bases in aqueous solution ranges from greater than 7 (the pH of pure water) to 14 (though some bases have pH values greater than 14).

  • Buffers Containing a Base and Conjugate Acid

    • In the more generalized Brønsted-Lowry definition, the hydroxide ion (OH-) is the base because it is the substance that combines with the proton.
    • Ammonia and some organic nitrogen compounds can combine with protons in solution and act as Brønsted-Lowry bases.
    • Reactions with weak bases result in a relatively low pH compared to strong bases.
    • A base dissociation constant (Kb) indicates the strength of the base.
    • Bases that have a large Kb will ionize more completely, meaning they are stronger bases.

  • Nature of Acids and Bases

    • Brønsted-Lowry acid: any substance that can act as a proton donor.
    • Acids + Bases Made Easy!
    • Part 1 - What the Heck is an Acid or Base?
    • Ever wondered what the heck an Acid or Base actually is?
    • In this video I introduce to you guys what the heck an Acid and Base really is forgetting the Lewis or Bronstead/Lowry definitions and then we'll go more in depth in parts 2,3, and 4.

  • Absolute Concentrations of the Acid and Conjugate Base

    • A buffer is an aqueous solution consisting of a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid.
    • Therefore, it is very important to be able to identify acid and conjugate base pairs.
    • A concentrated buffer can neutralize more added acid or base than a dilute buffer, because it contains more acid/conjugate base.
    • 8.1.3 Deduce the formula of the conjugate acid/base of any Brønsted-Lowry base/acid IB Chemistry SL - YouTube
    • The conjugate base is the other product, which has had a proton removed.

  • Carboxylic Acids

    • As proton donors, carboxylic acids are characterized as Brønsted-Lowry acids.
    • Carboxylic acids are generally produced from oxidation of aldehydes and hydrocarbons, and base catalyzed dehydrogenation of alcohols.
    • Upon exposure to a base, the carboxylic acid is deprotonated and forms a carboxylate salt.

  • Addition of Strong Brønsted Acids

    • As illustrated in the general equation in the previous concept, strong Brønsted acids such as HCl, HBr, HI & H2SO4, rapidly add to the C=C functional group of alkenes to give products in which new covalent bonds are formed to hydrogen and to the conjugate base of the acid.
    • Weak Brønsted acids such as water (pKa = 15.7) and acetic acid (pKa = 4.75) do not normally add to alkenes.
    • All the reagents discussed here are strong Brønsted acids so, as a first step, it seems sensible to find a base with which the acid can react.
    • The resulting acid-base equilibrium generates a carbocation intermediate (the conjugate acid of the alkene) which then combines rapidly with the anionic conjugate base of the Brønsted acid.
    • The more stable 2º-carbocation is formed preferentially, and the conjugate base of the Brønsted acid (chloride anion in the example shown below) then rapidly bonds to this electrophilic intermediate to form the final product.

  • Nitrogen Compounds

    • Liquid ammonia (boiling point 240 K) is amphiprotic (displaying either Brønsted-Lowry acidic or basic character) and forms ammonium and the less common amide ions (NH2−).
    • Ammonia has a pKa of 38, making the corresponding amide ions very strong bases.

  • Acid-Base Reactions

    • Organic chemists use two acid-base theories for interpreting and planning their work: the Brønsted theory and the Lewis theory.
    • According to the Brønsted theory, an acid is a proton donor, and a base is a proton acceptor.
    • Lewis bases are also Brønsted bases; however, many Lewis acids, such as BF3, AlCl3 and Mg2+, are not Brønsted acids.
    • Many carbocations (but not all) may also function as Brønsted acids.
    • In its Brønsted acid role the carbocation donates a proton to the base (hydroxide anion), and is converted to a stable neutral molecule having a carbon-carbon double bond.