What is the correct order of increasing acidity of the following acids;HF,HI,HCl,HClO4 and HBr.
HF<HCl<HBr<HI<HClO4
HF is the weakest; HClO4 the strongest.
To determine the correct order of increasing acidity for the given acids (HF, HI, HCl, HClO4, and HBr), we need to consider the factors that influence acidity.
1. Size of the atom: Acidity generally increases with increasing atom size. As the atom size increases, the acidity increases because the electron density is spread out over a larger volume, making it easier for the hydrogen ion (H+) to dissociate from the acid. Larger atoms also have weaker bonding, allowing for easier dissociation.
2. Electronegativity: Acidity generally increases as electronegativity decreases. Acids with lower electronegativity tend to have a weaker hold on their hydrogen ions and are therefore more likely to dissociate.
With these factors in mind, let's compare the given acids:
1. HF (Hydrofluoric acid):
- Fluorine is a small atom with high electronegativity.
- Because of fluorine's small size, the electron density around the hydrogen atom is high, making it less likely to dissociate.
- Therefore, HF is the weakest acid among the given acids.
2. HI (Hydroiodic acid):
- Iodine is a large atom with lower electronegativity compared to fluorine.
- Due to iodine's larger size, the electron density around the hydrogen atom is lower than in HF, making it easier for dissociation.
- Therefore, HI is stronger than HF.
3. HCl (Hydrochloric acid):
- Chlorine is smaller than iodine but larger than fluorine.
- HCl is stronger than HI but weaker than HF.
4. HClO4 (Perchloric acid):
- Perchloric acid has multiple oxygen atoms attached to chlorine.
- The oxygen atoms donate electron density, making it easier for dissociation.
- HClO4 is stronger than HCl, HI, and HF.
5. HBr (Hydrobromic acid):
- Bromine is larger than chlorine and has lower electronegativity.
- Due to the larger size and lower electronegativity, HBr is the strongest acid among the given acids.
The correct order of increasing acidity for the given acids is:
HF < HI < HCl < HClO4 < HBr