A student dissolves 12.0 g of MgSO_4 in enough water to make 500.0 mL of solution. What is the molarity of the magnesium sulfate solution that was formed?

• A. 0.200 M
• B. 0.120 M
• C. 0.240 M
• D. 0.500 M

Answer: (C)

Verified step by step guidance

1. First, calculate the molar mass of magnesium sulfate (MgSO_4). Add the atomic masses of Mg, S, and 4 O atoms: \( M_{MgSO_4} = M_{Mg} + M_S + 4 \times M_O \).
2. Next, convert the mass of MgSO_4 given (12.0 g) to moles using the molar mass: \( n = \frac{\text{mass}}{\text{molar mass}} = \frac{12.0\, \text{g}}{M_{MgSO_4}} \).
3. Convert the volume of the solution from milliliters to liters because molarity is expressed in moles per liter: \( V = 500.0\, \text{mL} = 0.5000\, \text{L} \).
4. Calculate the molarity (M) of the solution using the formula: \( M = \frac{n}{V} \), where \( n \) is the number of moles of solute and \( V \) is the volume of the solution in liters.
5. Finally, interpret the calculated molarity to select the correct answer from the given options.