Question

for the list of compounds, rank the compounds in strength from weakest acid to strongest acid.
weakest
strongest
answer bank
h₃p
h₄si
h₂s
hcl

Explanation:

Step1: Recall periodic acid trend

For binary acids (H-X) in the same period, acid strength increases with increasing electronegativity of the non-metal atom. The electronegativity order of the central atoms is: $\text{Si} < \text{P} < \text{S} < \text{Cl}$.

Step2: Relate to acid strength

Higher electronegativity of the central atom stabilizes the conjugate base, making the acid stronger. So the acid strength follows the reverse of the conjugate base stability trend, matching the electronegativity order.

Answer:

Weakest: $\text{H}_4\text{Si}$
$\text{H}_3\text{P}$
$\text{H}_2\text{S}$
Strongest: $\text{HCl}$