To determine which option best describes an Arrhenius acid-base reaction, let's break down the basic concept of Arrhenius acids and bases.
An Arrhenius acid is a substance that, when dissolved in water, increases the concentration of [tex]\(H^+\)[/tex] (hydrogen ions) or [tex]\(H_3O^+\)[/tex] (hydronium ions) in the solution. Examples include hydrochloric acid (HCl) and sulfuric acid (H_2SO_4).
An Arrhenius base is a substance that, when dissolved in water, increases the concentration of [tex]\(OH^-\)[/tex] (hydroxide ions) in the solution. Examples include sodium hydroxide (NaOH) and potassium hydroxide (KOH).
When an Arrhenius acid reacts with an Arrhenius base, the hydrogen ions ([tex]\(H^+\)[/tex]) from the acid combine with the hydroxide ions ([tex]\(OH^-\)[/tex]) from the base to form water ([tex]\(H_2O\)[/tex]). The other product of the reaction is usually a salt, which is composed of the cation from the base and the anion from the acid.
Therefore, the general form of an Arrhenius acid-base reaction is:
[tex]\[ \text{Acid} + \text{Base} \rightarrow \text{Salt} + \text{Water} \][/tex]
Let's evaluate the given options:
A. Acid + base [tex]$= H ^{+}+ OH ^{-}$[/tex] - This is not accurate as it represents the dissociation of an acid and a base but not their reaction.
B. Acid + base [tex]$=$[/tex] conjugate base + conjugate acid - This describes a Brønsted-Lowry acid-base reaction, not an Arrhenius acid-base reaction.
C. Acid + base [tex]$= H _2 O$[/tex] - This only refers to the formation of water and ignores the formation of salt, which is a key component of an Arrhenius acid-base reaction.
D. Acid + base [tex]$=$[/tex] salt + water - This is the correct description of an Arrhenius acid-base reaction.
Therefore, the best description of an Arrhenius acid-base reaction is:
D. Acid + base [tex]$=$[/tex] salt + water.
