An aqueous solution of a soluble compound (a nonelectrolyte)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/mole)of the compound? A)1.0 × 10³ B)2.7 × 10³ C)2.3 × 10² D)6.8 × 10² E)28

Question

Quizplus · Accepted Answer

The van't Hoff factor (i) for a non-electrolyte is 1. Therefore,

π = iMRT

where π is the osmotic pressure, M is the molarity, R is the gas constant, and T is the temperature in Kelvin. We can rearrange this equation to solve for M:

M = π / iRT

Substituting the given values and converting the volume to liters:

M = (1.2 atm) / (1 * 0.0821 L*atm/mol*K * 298 K) = 0.0488 mol/L

Now we can calculate the number of moles of solute in the solution:

moles = M * volume = 0.0488 mol/L * 0.250 L = 0.0122 mol

Finally, we can calculate the molar mass by dividing the mass of solute by the number of moles:

molar mass = mass / moles = 33.2 g / 0.0122 mol = 271.9 g/mol

Rounding to the nearest tenth gives 2.7 × 10¹³ g/mol, which is choice B.

An Aqueous Solution of a Soluble Compound (A Nonelectrolyte)is Prepared