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According to Arrhenius theory, which of the following can an acid be defined as?

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(A) A substance that changes the color of an aqueous solution.

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(B) A substance that ionizes in an aqueous solution to produce OH− ions.

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(C) A substance that fizzes when placed into an aqueous solution.

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(D) A substance that dissolves any substance placed into a solution of it.

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(E) A substance that ionizes in an aqueous solution to produce H+ ions.

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To solve this problem, we need to carefully read through each answer choice to determine if it is an accurate definition of an acid.

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The definition of the acid must correspond to the Arrhenius theory of acids and bases.

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This theory, proposed by Swedish scientist Svante Arrhenius in 1887, focused specifically on how acids and bases ionize or dissociate into ions when dissolved in water.

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The result of an acid or base ionizing in water is an aqueous solution containing dissolved ions.

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Let’s begin examining the answer choices.

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The statement in answer choice (A) describes the substance that changes the color of an aqueous solution.

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Arrhenius theory defines an acid based on the ability of the acid to ionize in an aqueous solution, not change the color of the solution.

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Because ionization is not described, answer choice (A) can be eliminated.

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Next, let’s take a look at answer choice (C).

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This statement describes a substance that fizzes when placed into an aqueous solution.

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The Arrhenius definition of an acid must include how an acid ionizes when dissolved in water.

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Because ionization is not described, answer choice (C) can also be eliminated.

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The statement in answer choice (D) describes a substance in a solution that will dissolve any substance placed into it.

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It’s important to recognize that Arrhenius theory is focused on what happens when an acid dissolves in water, not what happens when substances are dissolved in an acidic solution.

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We can eliminate answer choice (D) for this reason.

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And there are plenty of examples of substances that will not dissolve in an acidic solution.

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The only answer choices left our answer choices (B) and (E).

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Both of these answer choices describe a substance that ionizes in an aqueous solution, but only one of them is correct.

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The substance in answer choice (B) produces OH− ions when it ionizes in the solution.

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This statement is the definition of a base according to Arrhenius theory.

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An example of an Arrhenius base is potassium hydroxide or KOH.

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When solid potassium hydroxide dissolves in water, it ionizes to produce K+ and OH− ions in the solution.

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We can eliminate answer choice (B) because the statement is the definition of a base.

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Finally, answer choice (E) describes a substance that ionizes in an aqueous solution to produce H+ ions.

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This statement is the definition of an acid according to the Arrhenius theory.

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An example of an Arrhenius acid is hydrobromic acid or HBr.

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When dissolved in an aqueous solution, hydrobromic acid molecules ionize to produce H+ and Br− ions.

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The hydrogen ions produced are then accepted by water molecules in the aqueous solution forming H3O+ or hydronium ions.

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The statement that defines an acid according to the Arrhenius theory is answer choice (E), a substance that ionizes in an aqueous solution to produce H+ ions.