What is Acid Strength?
Acid strength is the capacity to lose H+ ions. In pure concentrations, a strong acid dissociates completely. You know acid’s physical and chemical properties. Simple ones include a pH below 7, a sour taste, and a reaction with alkalis to generate salts. Acid strength is interesting.
In this article, we will talk about acid strength and the factors which affect it.
What are Strong Acids and Weak Acids?
- Strong acids totally ionize in solution, while weak acids only partially ionize.
- Strong acids corrode flesh and inflict severe burns.
- Weak acids are moderately corrosive and found in food and the body.
- Strong acids include hydrochloric and sulphuric.
- Weak acids include ethanolic acid, citric acid (in citrus fruits), and acetic acid (in vinegar).
The following are strong acids in aqueous and dimethyl sulfoxide solutions.
| Acid | Formula | in water | in DMSO |
| Hydrochloric acid | HCl | −5.9 ± 0.4 | −2.0 ± 0.6 |
| Hydrobromic acid | HBr | −8.8 ± 0.8 | −6.8 ± 0.8 |
| Hydroiodic acid | HI | −9.5 ± 1 | −10.9 ± 1 |
| Triflic acid | H[CF3SO3] | −14 ± 2 | −14 ± 2 |
| Perchloric acid | H[ClO4] | −15 ± 2 | −15 ± 2 |
Factors Determining Acid Strength
As mentioned, acid strengths vary. Stronger acids have more dissociation. Let’s look at what affects acid strength. Two things affect acid dissociation.
- Strength of H-A bond
- Polarity of H-A bond
Stronger acid, weaker H-A bond. Greater H-A bond polarity increases acidity. Both conditions promote acid breakdown into H+ and A- simpler, increasing acidity.
Acid Strength Order
When comparing elements in the same group of the periodic table, H-A bond strength is a more relevant factor in acidity than polarity. As A descends a group, H-A bond strength diminishes, increasing acid strength. Group-17 hydrides have increasing acid strengths.
HF < HCl < HBr < HI
Factors Affecting Acid Strength
- It relies on the H-A bond’s strength. Less energy is required to break a connection with decreasing strength. Therefore, the acid is strong.
- The polarity of the H-A bond influences acidity. If the bond is extremely polar, the proton is more likely to leave the molecule, making the molecule acidic.
- However, bond strength is more essential when comparing acid strengths of elements in the same group of the periodic table based on the aforementioned two variables.
- However, when comparing the acid strengths of elements in the same row, the polarity of the H-A bond takes precedence.
- The atomic size of A influences the acid strength as well. As the atomic size increases, the link becomes weaker. Consequently, acid concentration rises.
Frequently Asked Questions – FAQs
Q.1 What makes an acid weak or strong?
Ans – Strong acids typically contain ions in solution, therefore the bonds holding H and A together must be weak. Strong acids readily dissociate into ions. Since weak acids frequently exist as molecules containing only a few ions in solution, the bonds between H and A must be solid.
Q.2 What is the strongest acid?
Ans – Because fluoroantimonic acid is actually a blend of hydrofluoric acid and pentafluoride antimony, carborane superacids can be called the strongest solar acid in the world. The pH value for carborane is -18.
Q.3 What factors affect acid strength?
Ans – This determines the H-A bond’s strength. The greater the bond, the more energy required to break it. Therefore, the acid is solid. The polarity of the H-A bond controls the acid’s strength.
Q.4 Which acid is the weakest?
Ans – Citric acid is a mild acid compared to sulphuric acid and hydrochloric acid because its solution contains extremely low amounts of H+ ions. Organic acid is citric acid, and most weak acids are organic acids.
Q.5 Which seven strong acids are there?
Ans – There are seven powerful acids: chloric acid, hydrobromic acid, hydrochloric acid, hydroiodic acid, nitric acid, perchloric acid, and sulfuric acid. However, inclusion on the list of strong acids does not indicate how dangerous or deadly an acid is.
Q.6 What is acidic strength and basic strength?
Ans – The terms strong and weak describe the electrical conductivity of acid and base solutions, respectively. It is a strong acid or base if the acid or base conducts electricity strongly. If the acid or base conducts electricity sluggishly, it is weak.
