What is acid strength?
The measurement of the ability of an acid to donate its H+ ion is known as the acid strength of that acid. Those acids with strong acid strength completely dissociate in solution, whether the solution is concentrated or dilute.
For example
There are some examples of strong acids which are given below:
- Hydrochloric acid
- Perchloric acid
- Nitric acid
- Sulphuric acid
Dependence of strength of organic acid and inorganic acid:
Organic acids:
Substituent effects are the factor that affects the strength of weak organic acids.
Inorganic acids:
The oxidation state of the atom is the factor that affects the strength of weak inorganic acids.
- The acidic strength of an acid also depends on the solvent.
- For example, HCl is the strong acid in aqueous solution but it is a weak acid in glacial acetic acid.
Factors affecting the acid strength:
There are some factors which are given below:
Strength of the bond
The strength of the H-A bond is one of the factors that influences acid strength.
- If the bond is weak then less amount of energy is required to break this bond. So, this is the strong acid
Polarity of the bond
- The polarity of the H and A bond is one of the factors which affects the acid strength. If the bond is more polar, then the proton is easily lost from the molecule. So, this is a strong acid.
Periodic trend
- Periodic trend is also the factor that affects the acid strength of the elements.
Size of the atoms
- The size of the atoms is one of the factors which influences the acid strength. As the size of the atom increases, the bond becomes weaker. As a result, the strength of the acid increases.
Inductive effect
- The inductive effect is one of the factors which affects the acid strength. For example, inorganic carboxylic acid is an electronegative substituent that pulls withdrawn electrons from the acidic bond through the inductive effect. Thus, its Pka value is decreased.
Strong acid:
An acid that is completely dissolved or dissociated in an aqueous solution, is known as a strong acid.
- Strong acid has a more ability to lose protons
- These have high pH values.
- Strong acids show irreversible reactions.
- For example, sulfuric acid, hydrochloric acid, perchloric acid, and nitric acid.
Weak acid:
An acid that is partially ionized in an aqueous solution, is known as weak acid.
- A weak acid can’t give many hydrogen ions in aqueous solution.
- It has a low pH value.
- Weak acids show a reversible reaction.
- For example, Oxalic acid, Phosphoric acid, Nitrous acid, Formic acid, Acetic acid, and Ascorbic acid.
