If you have a solution containing 120 g of NaCl dissolved in 480 g of water, what is the mass percent of NaCl in the solution?

• A. 20%
• B. 25%
• C. 12.5%
• D. 33%

Answer: (A)

Verified step by step guidance

1. Identify the components of the solution: the solute is NaCl with a mass of 120 g, and the solvent is water with a mass of 480 g.
2. Calculate the total mass of the solution by adding the mass of the solute and the solvent: \(\text{mass}_{\text{solution}} = \text{mass}_{\text{NaCl}} + \text{mass}_{\text{water}}\).
3. Write the formula for mass percent, which expresses the mass of the solute as a percentage of the total solution mass: \(\text{mass percent} = \left( \frac{\text{mass of solute}}{\text{mass of solution}} \right) \times 100\%\).
4. Substitute the known values into the formula: \(\text{mass percent} = \left( \frac{120\,\text{g}}{120\,\text{g} + 480\,\text{g}} \right) \times 100\%\).
5. Perform the division and multiplication to find the mass percent of NaCl in the solution.