Final answer:
The molarity of a 28.0% ethyl alcohol solution with a density of 0.9928 g/mL is calculated using the density and percentage by mass, resulting in a molarity of 6.03 M for the solution.
Step-by-step explanation:
To determine the molarity of a 28.0% ethyl alcohol, C₂H₅OH, solution with a density of 0.9928 g/mL, we first calculate the mass of ethanol in a given volume of the solution. Assume we have 1 liter (or 1000 mL) of solution to work with for easy calculation.
- Mass of solution = volume × density = 1000 mL × 0.9928 g/mL = 992.8 g
- Mass of ethanol in solution = 28.0% of total mass = 0.28 × 992.8 g = 277.984 g
- Moles of ethanol = mass/molar mass = 277.984 g / 46.07 g/mol = 6.03 mol
- The molarity of the solution = moles/volume (in L) = 6.03 mol / 1 L = 6.03 M
Note that we have used the molar mass of ethanol which is 46.07 g/mol to convert from grams to moles.