What is the mass percent of a solution prepared by dissolving 30.0 g of NaOH in 120.0 g of H2O?

To calculate the mass percent of the NaOH solution, we first need to determine the total mass of the solution and then find the mass percent of NaOH in that solution.

The mass percent (m/m) is calculated using the formula:

[

\text{Mass percent} = \left( \frac{\text{mass of solute}}{\text{mass of solute} + \text{mass of solvent}} \right) \times 100

]

In this instance, the mass of the solute (NaOH) is 30.0 g, and the mass of the solvent (H2O) is 120.0 g. The total mass of the solution is the sum of the mass of the solute and the mass of the solvent:

[

\text{Total mass of solution} = 30.0 , \text{g NaOH} + 120.0 , \text{g H2O} = 150.0 , \text{g}

]

Next, plug the values into the mass percent formula:

[

\text{Mass percent} = \left( \frac{30.0 , \text{g NaOH}}{