Calculate the concentration of H3O⁺ in a solution that contains 1.8 × 10-5 M OH⁻ at 25°C. Identify the solution as acidic, basic, or neutral. A. 5.5 × 10-10 M, acidic B. 9.2 × 10-1 M, acidic C. 5.5 × 10-10 M, basic D. 1.8 × 10-10 M, neutral

A. 5.5 × 10⁻¹⁰ M, acidic

Explanation:

Step 1: Given data

Concentration of H₃O⁺: 1.8 10⁻⁵ M

Step 2: Calculate the concentration of OH⁻

We will use the ionic product of water.

Kw = 1.0 × 10⁻¹⁴ = [H₃O⁺] × [OH⁻]

[OH⁻] = 1.0 × 10⁻¹⁴/[H₃O⁺] = 1.0 × 10⁻¹⁴/1.8 10⁻⁵ = 5.5 × 10⁻¹⁰ M

Step 3: Determine if the solution is acidic, basic or neutral

Then, the solution is acidic.

125

Explanation:

Protons + neutrons = mass number

Protons = 82

Mass number = 207

Number of neutrons = 207-82=125