Question

What is an acid, a base, and a neutral substance?

Answer 1

Hint: In chemistry, substances are attributed to different physical and chemical properties. Based on one such property, substances are termed as an acid, a base, or a neutral compound. Whether a substance is acidic, basic, or neutral depends upon the type of attraction between its atoms and molecules.

Complete answer:
Every known compound around us is either an acid, a base, or a neutral compound. It is very important to have a knowledge of which compound is acidic, basic, and neutral because these all have different properties and can be used in different ways. So, let us understand the difference between all of these.
-An acid is a substance that furnishes hydrogen ions $\left( {{\text{H}}^{+}} \right)$ or hydronium ions \[\left( {{\text{H}}_{\text{3}}}{{\text{O}}^{+}} \right)\] when present in its aqueous solution. Acids are usually corrosive in nature and turn blue litmus red. They have a pH value always less than 7.
\[\begin{align}
  & \text{HCl(aq)}\rightleftharpoons {{\text{H}}^{\text{+}}}\text{(aq)}+\text{C}{{\text{l}}^{\text{-}}}\text{(aq)} \\
 & \text{or HCl(aq)}+{{\text{H}}_{\text{2}}}\text{O(aq)}\rightleftharpoons {{\text{H}}_{\text{3}}}{{\text{O}}^{\text{+}}}\text{(aq)}+\text{C}{{\text{l}}^{\text{-}}}\text{(aq)} \\
\end{align}\]
Acids can be found in many substances such as, citrus fruits contain citric acid and vinegar contains acetic acid. Other acids such as hydrochloric acid $\left( \text{HCl} \right)$ and sulphuric acid $\left( {{\text{H}}_{\text{2}}}\text{S}{{\text{O}}_{\text{4}}} \right)$ are known as mineral acids.
-A base is a substance that furnishes hydroxyl ions $\left( \text{O}{{\text{H}}^{-}} \right)$ when present in its aqueous solution. Bases are sleepy and soapy in nature and turn red litmus blue. They show a pH value greater than 7.
\[\text{NaOH(aq)}\rightleftharpoons \text{N}{{\text{a}}^{\text{+}}}\text{(aq)}+\text{O}{{\text{H}}^{\text{-}}}\text{(aq)}\]
Bases are found in soaps and baking soda that we use in our homes.
-A neutral substance is neither acidic nor basic. When an acid reacts with a base, it forms salt and water. This reaction is known as the neutralization reaction. Hydrogen ions from an acid react with hydroxyl ions from the base and form a neutral water molecule along with salt.
\[\text{HCl(aq)}+\text{NaOH(aq)}\to \text{NaCl(s)}+{{\text{H}}_{\text{2}}}\text{O(aq)}\]
The pH of a neutral substance is 7. Thus, the example of neutral substances includes water and salts like sodium chloride (NaCl).

Note:
Our stomach contains dilute hydrochloric acid which helps in breaking down food. But when we eat too much, the stomach releases too much acid, and indigestion happens. To neutralize excess acid, we take an antacid that is a base that neutralizes this excess acid and we get relief.