Question

Which of the following compounds is not an Arrhenius acid?

1) HCl
2) H₂SO₄
3) NaOH
4) HNO₃

Answer 1

NaOH is not an Arrhenius acid; it is an Arrhenius base because it increases the concentration of hydroxide ions (OH⁻) in water. Therefore, option 3, NaOH, is the one that does not fit the definition of an Arrhenius acid.

Step-by-step explanation:

The compound that is not an Arrhenius acid among the options provided is NaOH (sodium hydroxide). According to Arrhenius theory, an acid is a substance that increases the concentration of hydrogen ions (H⁺) when dissolved in water. Looking at the compounds listed:

1. HCl (hydrochloric acid) is an Arrhenius acid since it dissociates in water to produce H⁺.
2. H₂SO₄ (sulfuric acid) is also an Arrhenius acid because it releases H⁺ ions in solution.
3. NaOH is an Arrhenius base as it increases the concentration of hydroxide ions (OH⁻) in water.
4. HNO₃ (nitric acid) is an Arrhenius acid because it dissociates to yield H⁺ ions.

Therefore, option 3, NaOH, is the one that does not fit the definition of an Arrhenius acid.

An Arrhenius acid is a compound that increases the concentration of H+ ions in an aqueous solution. From the given compounds, HCl, H₂SO₄, and HNO₃ are all Arrhenius acids because they ionize in water to produce H+ ions. However, NaOH is not an Arrhenius acid. It is actually an Arrhenius base because it increases the concentration of OH- ions in water.