GED Science TestPhysical ScienceMedium
A technician is preparing a solution by dissolving 30 grams of sugar in 170 grams of water. What is the mass percent concentration of sugar in this solution?
- A17.6%
- B20%
- C85%
- D15%
Show answer & explanationAnswer & explanation
Correct answer: D. 15%
Mass percent concentration is calculated as (mass of solute / mass of solution) × 100%. The mass of the solute (sugar) is 30 g. The mass of the solution is the mass of solute + mass of solvent = 30 g + 170 g = 200 g. So, (30 g / 200 g) × 100% = 0.15 × 100% = 15%.
Why the other options are wrong
- A. This would be (30/170)*100%, which incorrectly uses only the solvent mass in the denominator.
- B. This would be (30/150)*100%, assuming incorrect total mass.
- C. This is the mass percent of water, not sugar, or an incorrect calculation.
Mass Percent Concentration
Mass percent concentration is a way to express the concentration of a solution, defined as the mass of the solute divided by the total mass of the solution, multiplied by 100%.
- Mass % = (Mass of Solute / Mass of Solution) × 100%
- Mass of Solution = Mass of Solute + Mass of Solvent
- Units of mass must be consistent (e.g., grams)
Memory trick: Percent Mass = Part over Whole x 100