Question

Between the hydracids HF, HCl, HBr, and HI, which is the strongest and why?

Answer 1

Step 1: Strongest acid:

• The strength of the acids is determined by how easily they lose their hydrogen ($H^{+}$) ions.
• Among these four hydracids, $\mathrm{HF},\mathrm{HCl},\mathrm{HBr},\mathrm{and}\mathrm{HI}$, $\mathrm{HI}$is the strongest acid.

Step 2: Reason for the strongest:

• In $\mathrm{HI}$, Iodine$\left(\mathrm{I}\right)$ is less electronegative and the size of iodine is larger.
• So bonding between Hydrogen and Iodine is weaker compared to other halogens ($\mathrm{Cl},\mathrm{Br},\mathrm{and}\mathrm{F}$), so $H^{+}$ions can be easily removed.
• Due to the easy liberation of $H^{+}$ions, $HI$ is the strongest acid.