Problem 57 - Chemistry

Question

Calculate the concentration of an aqueous HI solution that has \(\mathrm{pH}=2.50 .\) HI is a strong acid.

Step-by-Step Solution

Answer

The concentration of the aqueous HI solution can be calculated using the given pH value and the formula [H₃O⁺] = 10^(-pH). With a pH of 2.50, [H₃O⁺] ≈ 3.16 × 10⁻³ M. Since HI is a strong acid and dissociates completely in water, the concentration of the HI solution is approximately 3.16 × 10⁻³ M.

Step 1: Understand the definition of pH

pH is defined as the negative logarithm of the H₃O⁺ ion concentration: pH = -log₁₀([H₃O⁺]) We are given the pH value (2.50), and we need to find the concentration of the H₃O⁺ ions, represented as [H₃O⁺].

Step 2: Calculate the concentration of H₃O⁺ ions

To find [H₃O⁺], we can use the given pH value by rearranging the pH formula: [H₃O⁺] = 10^(-pH) Substitute the given pH value (2.50) into the formula: [H₃O⁺] = 10^(-2.50) Calculate the concentration of H₃O⁺ ions: [H₃O⁺] ≈ 3.16 × 10⁻³ M

Step 3: Determine the concentration of the HI solution

Since HI is a strong acid, it dissociates completely in water. That means that the concentration of H₃O⁺ ions is equal to the concentration of the HI solution. Therefore, the concentration of the aqueous HI solution is approximately 3.16 × 10⁻³ M.