A 3.00 L solution of 0.0200 M ammonium sulfide ((NH_4)_2S) is prepared. What is the mass of (NH_4)_2S present in the solution? (Molar mass of (NH_4)_2S = 68.15 g/mol)

• A. 4.09 g
• B. 0.409 g
• C. 2.05 g
• D. 1.36 g

Answer: (A)

Verified step by step guidance

1. Identify the given information: volume of solution \(V = 3.00\ \text{L}\), molarity \(M = 0.0200\ \text{mol/L}\), and molar mass of ammonium sulfide \(M_{molar} = 68.15\ \text{g/mol}\).
2. Calculate the number of moles of ammonium sulfide in the solution using the formula \(n = M \times V\), where \(n\) is the number of moles.
3. Use the calculated moles to find the mass of ammonium sulfide by applying the formula \(\text{mass} = n \times M_{molar}\).
4. Substitute the values into the mass formula: multiply the moles by the molar mass to get the mass in grams.
5. Interpret the result as the mass of ammonium sulfide present in the 3.00 L solution.