Discuss the factors affecting acid strength with examples.

(N/A) The strength of an acid is determined by its ability to donate $H^+$ ions.
$(i)$ Bond Strength: As the strength of the $H-A$ bond decreases,the energy required to break the bond decreases,making $HA$ a stronger acid.
$(ii)$ Bond Polarity: As the electronegativity difference between $H$ and $A$ increases,the bond becomes more polar,facilitating the release of $H^+$. Thus,$\text{Polarity} \propto \text{Acidity}$.
$(iii)$ Trends in a Period: Across a period,electronegativity of $A$ increases,which increases bond polarity. For example: $CH_4 < NH_3 < H_2O < HF$. Here,acid strength increases as electronegativity of $A$ increases.
$(iv)$ Trends in a Group: Down a group,the size of $A$ increases,which significantly decreases the $H-A$ bond strength. This is the dominant factor. For example: $HF < HCl < HBr < HI$. Here,acid strength increases as the size of $A$ increases.