Bases produce hydroxide (OH- ions) in water. NH3 (ammonia) is a base, but there is no hydroxide in NH3. Why?
Bases PRODUCE hydroxide ions in water. The secret word in your sentence is produce
So NH3 + HOH ==> NH4^+ + OH^-
To understand why NH3 (ammonia) is considered a base without containing hydroxide ions, it is important to first understand the concept of Arrhenius theory of acids and bases.
According to the Arrhenius theory, an acid is a substance that releases hydrogen ions (H+) when dissolved in water, while a base is a substance that releases hydroxide ions (OH-) in water. However, this definition is limited to only substances that produce H+ or OH- ions when dissolved.
NH3 (ammonia) does not contain hydroxide (OH-) ions, but it still behaves as a base. This is because there is another definition of bases known as the Brønsted-Lowry theory. According to this theory, a base is a substance that can accept a proton (H+ ion) from another substance.
In the case of NH3, it can act as a base by accepting a proton (H+) from an acid. When NH3 accepts a proton, it forms the ammonium ion (NH4+). The reaction can be represented as follows:
NH3 + H+ → NH4+
In this reaction, NH3 receives the proton from the acid, which causes it to act as a base. Even though NH3 does not produce hydroxide ions, it can still participate in acid-base reactions by accepting protons.
It is important to note that different theories provide different perspectives on acids and bases. While the Arrhenius theory focuses on hydroxide ions for bases, the Brønsted-Lowry theory broadens the definition to include substances that can accept protons.