A 635g sample of organic compound is dissolved in water and

A 6.35g sample of organic compound is dissolved in water and diluted to a total volume of 375mL. The resulting solution is found to have an osmotic pressure of 1.71atm and 23 Celsius. What is the molar mass of the organic compound in solution?

Solution

By definition

osmotic pressure = C x R x T

given

osmotic pressure = 1.71 atm

Temperature (T) = 23 C + 273 C = 296 K

R = gas constant = 0.0821 L atm / mol K

plug in the values

1.71 atm = C x 0.0821 ( L atm / mol K) x 296 K

C = 0.07036 mol / L

so

concentration = 0.07036 mol / L

now

moles of compound = 0.375 L x 0.07036 mol / L

moles of compound = 0.0264 mol

now

molar mass of compound = 6.35 g / 0.0264 mol

molar mass of compound = 240.647 g/mol