A neutralization reaction is shown
below. Aqueous HNO3 plus aqueous KOH turns
into aqueous KNO3 plus liquid H2O. What is the acid in this
equation? What is the base in this
equation? What is the salt in this
The general form of a
neutralization reaction is that an acid and a base added together produce water and
a salt. This multipart question is asking
us to look at the four compounds listed in the chemical equation and identify which
one is the acid, which one is the base, and which one is the salt.
If we look again at the general
equation for a neutralization reaction, we can see that the acid and base are the
reactants of the reaction on the left side of the equation, while the salt is one of
the products on the right side of the equation. Note that we cannot simply say that
the acid comes first, the base comes second, the water comes third, and the salt
comes fourth. The reactants on the left-hand side
of the equation could be listed in any order, and the products on the right-hand
side of the equation could be listed in any order.
Let’s start by identifying the
salt. In chemistry, a salt is an ionic
compound consisting of a positive ion and a negative ion. It’s a product of a neutralization
reaction. So it will appear on the right-hand
side of the equation. Thankfully, it is not too difficult
to identify which of the products is which. Liquid H2O is also known as water,
leaving aqueous KNO3, the ionic compound made up of the positive potassium ion and
the negative nitrate ion, to be the salt.
Next, we need to identify which is
the acid and which is the base. Based on the general formula, we
know that the acid and the base are the reactants of the neutralization
reaction. So of the two reactants on the
left-hand side of the equation, HNO3 and KOH, one will be the acid and one will be
the base. How do we determine which one is an
acid and which one is a base?
Well, acids produce hydrogen ions
when dissolved, while bases produce hydroxide or OH− ions when dissolved. If we break down these compounds
into their constituent ions, we can see that HNO3 produces hydrogen ions, while KOH
produces hydroxide ions. This means that HNO3 is our acid
and KOH is our base.
Note that there are some bases that
don’t produce hydroxide ions. However, the acid will still
produce hydrogen ions. So you can identify the acid and
base in this case by first identifying the acid. Neutralization reactions will
always follow the general formula of acid plus base produces water and a salt. If we can identify the reactant
that produces hydrogen ions, the reactant that produces hydroxide ions, and the
product that is an ionic compound, we can identify the acid, base, and salt,
In the neutralization reaction
shown below, the acid is HNO3, the base is KOH, and the salt is KNO3.