What is the molarity of a solution containing 28.6 grams of NH_3 in a total volume of 3.5 L?

• A. 0.48 M
• B. 1.2 M
• C. 0.24 M
• D. 2.4 M

Answer: (A)

Verified step by step guidance

1. Identify the formula for molarity, which is the number of moles of solute divided by the volume of the solution in liters: \(M = \frac{\text{moles of solute}}{\text{volume of solution in liters}}\).
2. Calculate the number of moles of NH\(_3\) by using its molar mass. First, find the molar mass of NH\(_3\) by adding the atomic masses: N (14.01 g/mol) + 3 × H (1.008 g/mol) = 17.034 g/mol. Then, calculate moles using \(\text{moles} = \frac{\text{mass}}{\text{molar mass}} = \frac{28.6 \text{ g}}{17.034 \text{ g/mol}}\).
3. Use the volume of the solution given, which is 3.5 L, directly in the molarity formula.
4. Substitute the moles of NH\(_3\) and the volume into the molarity formula: \(M = \frac{\text{moles of NH}_3}{3.5 \text{ L}}\).
5. Perform the division to find the molarity, which will give you the concentration of the NH\(_3\) solution in moles per liter (M).