Yes, strong acids are completely soluble in water.
Understanding Strong Acid Solubility
When strong acids are added to water, they readily dissolve. More significantly, they undergo a process called complete dissociation or ionization. This means that the acid molecules break apart entirely into their constituent ions within the water solution.
Why are Strong Acids Completely Soluble?
According to the reference provided, "Strong acids like HCl and HBr are completely soluble due to their high ionic character."
This "high ionic character" refers to the strong tendency of strong acid molecules to donate a proton (H⁺) to water molecules, forming hydronium ions (H₃O⁺) and the corresponding anion. This complete reaction with water drives the dissolving process to completion, resulting in a solution where virtually none of the original acid molecules remain intact; they exist solely as ions.
Examples of Strong Acids
Common examples of strong acids that exhibit complete solubility include:
- Hydrochloric acid (HCl)
- Hydrobromic acid (HBr)
- Sulfuric acid (H₂SO₄)
- Nitric acid (HNO₃)
- Perchloric acid (HClO₄)
As noted in the reference, HCl and HBr are specifically highlighted as being completely soluble.
Strong vs. Weak Acid Solubility
It's important to distinguish the behavior of strong acids from that of weak acids. The reference states, "Weak acids like CH3COOH are not completely soluble and remain partially as molecules in solution."
While weak acids do dissolve in water, they do not dissociate completely. A significant portion of a weak acid remains as intact molecules in the solution, with only a fraction breaking down into ions. This partial dissociation is a key difference compared to the complete dissociation seen with strong acids.
Here's a simple comparison:
| Feature | Strong Acids | Weak Acids |
|---|---|---|
| Solubility | Completely soluble | Generally soluble, but dissociation is partial |
| Dissociation | Dissociate almost 100% into ions | Dissociate only partially (typically < 10%) |
| Behavior in Water | Exist primarily as ions | Exist as a mixture of molecules and ions |
| Example (from ref) | HCl, HBr | CH3COOH (Acetic Acid) |
In summary, the high tendency for strong acids to completely dissociate into ions when mixed with water is the reason they are considered completely soluble.
