What mass of Na2SO4 is required to prepare 2.5 L of a 2.0 M solution?

• A. 142 g
• B. 710 g
• C. 500 g
• D. 355 g

Answer: (B)

Verified step by step guidance

1. Identify the given information: volume of solution (V) = 2.5 L and molarity (M) = 2.0 M. Molarity is defined as moles of solute per liter of solution.
2. Use the molarity formula to find the number of moles of Na2SO4 needed: \(\text{moles} = M \times V = 2.0 \times 2.5\).
3. Calculate the molar mass of Na2SO4 by adding the atomic masses of its elements: sodium (Na), sulfur (S), and oxygen (O). The formula is \(\text{molar mass} = 2 \times \text{atomic mass of Na} + 1 \times \text{atomic mass of S} + 4 \times \text{atomic mass of O}\).
4. Convert moles of Na2SO4 to mass using the molar mass: \(\text{mass} = \text{moles} \times \text{molar mass}\).
5. The resulting mass is the amount of Na2SO4 required to prepare 2.5 L of a 2.0 M solution.