Molecular Structure of Acids and Bases

Molecular Structure of Acids

Acids are substances that can donate a proton (H+) or accept an electron pair in reactions.
In water, acids dissociate into hydronium ions (H3O+) and anions. For example, hydrochloric acid (HCl) dissociates into hydronium and chloride ions.
Acids generally have a sour taste and can be found in substances such as vinegar (acetic acid) and lemon juice (citric acid).
The strength of an acid is determined by its ability to donate H+ ions. The stronger the acid, the more readily it will donate a proton.
Strong acids dissociate completely in water, releasing all their H+ ions. Common strong acids include sulphuric acid (H2SO4), nitric acid (HNO3), and hydrochloric acid (HCl).
Weak acids do not dissociate completely in water, meaning only a fraction of the acid molecules release their H+ ions. Examples include acetic acid and citric acid.
Acids react with bases in a reaction called neutralisation, producing a salt and water.

Molecular Structure of Bases

Bases are substances capable of accepting protons (H+) or donating electron pairs in reactions.
In water, bases dissociate to produce hydroxide ions (OH-) and cations.
Bases tend to have a bitter taste and a slimy or soapy feel. They can be found in substances such as baking soda (sodium bicarbonate) and ammonia (NH3).
Just like acids, bases can be categorised as strong or weak. Strong bases, like sodium hydroxide, dissociate completely in water, while weak bases, like ammonia, do not.
Some bases, known as alkalis, are bases that are soluble in water. They produce hydroxide ions when dissolved in water.
The reaction between acids and bases (neutralisation) results in the formation of a salt and water.
Bases have many uses in household cleaning products and industrial processes such as the manufacture of soap and paper.

Acid-Base Reactions

During an acid-base reaction, there’s transfer of a proton (H+) from the acid to the base. This is the H+ ion that the acid loses, and the base gains.
The reaction forms a conjugate acid (from the base) and a conjugate base (from the acid).
The strength of a conjugate acid or base depends on how readily it regains or loses a proton.

Remember: Understanding the structure and behaviour of acids and bases at the molecular level is fundamental to mastering many aspects of chemistry, including reactions, titrations, and more. It’s pivotal to your study of the Acids and Bases topic.