Difference Between Acid and Base

Main Difference – Acid vs Base

Acid and Base are two very common terms in Chemistry and are used to differentiate between two large sets of compounds depending on their chemical behavior. In general, chemical compounds can be categorized into three main types based on dissolution; namely, Acids, Bases and Salts. Acids are chemical compounds that act as proton donors and can be easily recognized due to the possession of a releasable H⁺ ion. Bases are chemical compounds that act as proton acceptors and can be easily recognized in most cases, (inorganic bases) due to its possession of a releasable OH^– ion. The main difference between acid and base is that acids act as proton donors whereas base act as proton acceptors. Upon the reaction of acids and bases in solutions, the H⁺ ions are neutralized by OH^– ions, and they form water molecules together. And their ionic counterparts get together to form salts.

What is an Acid

According to chemical theories, an acid can be defined in many ways. According to the Arrhenius definition, an acid is a substance that increase the concentration of H⁺ ions when dissolved in water. According to the Brønsted-Lowry definition, an acid is a substance that can act as a proton donor. Therefore, the easier and quicker the compound could get deprotonated, the stronger its acidity is. According to the Lewis definition of acids, they are substances that can accept a pair of electrons. In this case, all metal cations and any electron deficient molecule can act as an acid. The more readily an acid can accept a pair of electrons, the higher its Lewis acidity is.

In general, acids are found at a pH value of less than 7. Strong acids have lower pH values. Acids react with bases to form salts. They are able to turn blue litmus paper into red. They also have a sour taste. (However it is not advisable to taste strong acids). Some common examples of acids are; Hydrochloric acid (HCl), Sulphuric acid (H₂SO₄), Acetic acid (CH₃COOH), etc.

Sulphuric acid on a piece of towel

What is a Base

Bases can also be defined from different points of view using the definitions above. Therefore, an Arrhenius base is a substance that increases the concentration of OH^– ions when dissolved in water. A Brønsted-Lowry base is a substance that can act as a proton acceptor. Therefore, the more readily a compound accepts protons, the higher its Brønsted-Lowry basicity is. According to the Lewis definition, bases are substances that can accept a pair of electrons. And the easier it is for a base to accept a pair of electrons, the stronger its Lewis basicity is.

In general, bases are found at a pH value of higher than 7. Strong bases have high pH values. They react with acids to form salts. They are able to turn red litmus paper into blue. They also taste slightly soapy. (However it is not advisable to taste strong bases). Some common examples of bases are; Sodium Hydroxide (NaOH), Calcium Hydroxide (Ca(OH)₂), NH_3, etc.