The water treatment plant adds chlorine gas to the municipal water supply to control microorganisms. If a technician adds Cl2 at a rate of 1 mg per liter of water,
what is the molar concentration of chlorine in the drinking water?

1 × 10⁻⁵ M

Explanation:

Step 1: Given data

Step 2: Convert the concentration of chlorine from mg/L to g/L

We will use the conversion factor 1 g = 10³ mg.

1 mg/L × 1 g/10³ mg = 1 × 10⁻³ g/L

Step 3: Convert the concentration of chlorine from g/L to mol/L (molar)

We will use the molar mass of chlorine: 70.91 g/mol.

1 × 10⁻³ g/L × 1 mol/70.91 g = 1 × 10⁻⁵ mol/L = 1 × 10⁻⁵ M