In a study designed to prepare new gasoline-resistant coating, a polymer chemist dissolves 6.061 g poly(vinyl alcohol) in enough water to make 100.0 mL of solution. At 25 ° C, the osmotic pressure of this solution is 0.248 atm. What is the molar mass of the polymer sample?

Question

Quizplus · Accepted Answer

The molar mass of the polymer can be calculated using the formula for osmotic pressure: $\pi = \frac{n}{V}RT$, where $\pi$ is the osmotic pressure, $n$ is the number of moles of solute, $V$ is the volume of the solution in liters, $R$ is the gas constant (0.0821 L·atm/(K·mol)), and $T$ is the temperature in Kelvin. Rearranging the formula to solve for $n$, we get $n = \pi V / RT$. Substituting the given values ($\pi = 0.248$ atm, $V = 0.1$ L, $T = 298$ K), we find the number of moles of the polymer. Then, the molar mass (M) is the mass of the polymer divided by the number of moles ($M = \text{mass} / n$). The correct calculation leads to a molar mass that matches choice D.

In a Study Designed to Prepare New Gasoline-Resistant Coating, a Polymer