A solution is prepared by dissolving 17.5 g of MgCl_2 in 85.0 g of H_2O. What is the mass percent of MgCl_2 in the solution?

• A. 11.5%
• B. 14.0%
• C. 17.1%
• D. 20.6%

Answer: (C)

Verified step by step guidance

1. Identify the components of the solution: the solute is MgCl_2 and the solvent is H_2O.
2. Calculate the total mass of the solution by adding the mass of MgCl_2 and the mass of H_2O: \(\text{mass}_{\text{solution}} = \text{mass}_{\text{MgCl}_2} + \text{mass}_{\text{H}_2\text{O}}\).
3. Use the formula for mass percent, which is the mass of the solute divided by the total mass of the solution, multiplied by 100: \(\text{mass percent} = \left( \frac{\text{mass}_{\text{solute}}}{\text{mass}_{\text{solution}}} \right) \times 100\).
4. Substitute the given values into the formula: \(\text{mass percent} = \left( \frac{17.5\,\text{g}}{17.5\,\text{g} + 85.0\,\text{g}} \right) \times 100\).
5. Perform the division and multiplication to find the mass percent of MgCl_2 in the solution.