Concentration Question

Question

A product gives the instructions to use 1mL of product per L of water. Using this ratio, calculate the concentration of Cu²⁺ (in mol/L) that the product must have to achieve the desired 1ppm Cu²⁺.

Answer 1

To achieve 1 ppm of Cu²⁺:

1. 1 ppm = 1 mg/L = 1 × 10⁻³ g/L
2. Molar mass of Cu²⁺ = 63.55 g/mol
3. Moles of Cu²⁺ in 1 mg = 1 × 10⁻³ g ÷ 63.55 g/mol = 1.57 × 10⁻⁵ mol
4. Since 1 mL of product is added per 1 L of water, the concentration of Cu²⁺ in the product must be 1.57 × 10⁻² mol/L.