Answer
The $HI$ concentration in this solution is equal to $3.2 \times 10^{-3}M$
Work Step by Step
Since $HI$ is a strong acid, $[H_3O^+] = [HI]_{initial}$
1. Calculate the hydronium ion concentration in this solution:
$[H_3O^+] = 10^{-pH}$
$[H_3O^+] = 10^{- 2.50}$
$[H_3O^+] = 3.2 \times 10^{- 3}M$
Therefore, $[HI]_{initial} = 3.2 \times 10^{-3}M$