An aqueous solution of a soluble compound (anonelectrolyte) is prepared by dissolving 33.2 g of the compound in sufficient water to form 250 mL of solution. The solution has an osmotic pressure of 1.2 atm at 25 °C. What is the molar mass (g/mL) of the compound? A) 2.3 × 10² B) 1.0 × 10³ C) 2.7 × 10³ D) 6.8 × 10² E) 28

Question

Quizplus · Accepted Answer

The van't Hoff factor for anonelectrolytes is 1, so we can use the following equation to solve for the molar mass:
π = MRTi
where π is the osmotic pressure, M is the molar mass, R is the gas constant (0.0821 L·atm/mol·K), T is the temperature in kelvins (298 K), and i is the van't Hoff factor (1).
Plugging in the given values:
1.2 atm = M(0.0821 L·atm/mol·K)(298 K)(1) / (0.250 L)
M = 2.72 g/mol
Therefore, the molar mass (g/mol) of the compound is 2.72, which is closest to choice C (2.7 × 10¹²).

An Aqueous Solution of a Soluble Compound (Anonelectrolyte) Is Prepared