The concentration of H3O+ in human sweat can be as low as 2.5 × 10-6. The concentration of OH- in the sweat is , and this solution is (acidic, basic, neutral).

[OH⁻] = 4.0 × 10⁻⁹ M

Acidic

Explanation:

Step 1: Given data

Step 2: Calculate the concentration of OH⁻

We will use the following expression.

[H₃O⁺].[OH⁻] = Kw = 1.0 × 10⁻¹⁴

[OH⁻] = 1.0 × 10⁻¹⁴/[H₃O⁺] = 1.0 × 10⁻¹⁴/2.5 × 10⁻⁶ = 4.0 × 10⁻⁹ M

Step 3: Calculate the pH

We will use the following expression.

pH = -log [H₃O⁺] = -log 2.5 × 10⁻⁶ = 5.6

Since the pH < 7, the solution is acidic.

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).