Question

What will be the molar concentration of ammonium ion in a 100 ppb ammoniacal solution?

• A. 5.56 mol/L
• B. 5.56 × 10^-3 mol/L
• C. 5.56 × 10⁴ mol/L
• D. 5.56 × 10^-6 mol/L

Hint:

The molar concentration from a ppb value can be determined using Moles/L formula.

Answer 1

The Correct Option is D

A concentration of 100 ppb corresponds to 100 μg/L of ammonia (NH₃). The molar concentration of ammonium ions (NH₄⁺) is calculated as follows:

• Molar mass of NH₃: 17 g/mol
• Moles of NH₃ per litre:

\( \frac{100 \times 10^{-6}}{17} = 5.88 \times 10^{-6} \, \text{mol/L} \)

Therefore, the approximate molar concentration of ammonium ion is \( 5.56 \times 10^{-6} \, \text{mol/L} \).