In a laboratory experiment, a 10.0-mL sample of NaCl solution is poured into an evaporating dish with a mass of 24.10 g. The combined mass of the evaporating dish and NaCl solution is 36.15 g. After heating, the evaporating dish and dry NaCl have a combined mass of 25.50 g. (9.4) a. What is the mass percent (m/m) of the NaCl solution?

Verified step by step guidance

1. Calculate the mass of the NaCl solution by subtracting the mass of the empty evaporating dish from the combined mass of the dish and solution.
2. Determine the mass of the NaCl by subtracting the mass of the empty evaporating dish from the combined mass of the dish and dry NaCl.
3. Calculate the mass of the water in the solution by subtracting the mass of the NaCl from the mass of the NaCl solution.
4. Use the formula for mass percent (m/m): (mass of solute / mass of solution) * 100% to find the mass percent of NaCl in the solution.
5. Substitute the mass of NaCl and the mass of the NaCl solution into the formula to calculate the mass percent.

Key Concepts

Mass Percent (m/m)

Mass percent (m/m) is a way to express the concentration of a component in a solution, calculated as the mass of the solute divided by the total mass of the solution, multiplied by 100. In this context, it helps determine how much of the NaCl solution is made up of NaCl by comparing the mass of NaCl to the total mass of the solution.

Evaporation and Mass Loss

Evaporation is the process where liquid turns into vapor, often resulting in a loss of mass when a solute is dissolved in a solvent. In this experiment, heating the NaCl solution causes the water to evaporate, leaving behind solid NaCl, which is crucial for calculating the mass percent of the solution.

Calculating Mass of Solute

To find the mass of the solute (NaCl) in the solution, one must subtract the mass of the evaporating dish and dry NaCl from the mass of the dish with the NaCl solution. This calculation is essential for determining the mass percent, as it provides the necessary mass of NaCl to use in the mass percent formula.