Question

A compound is found to have a molar mass of 598 g/mol. if 0.0358 g of the compound is dissolved in enough water to make 175 ml of solution at 25°c, what is the osmotic pressure of the resulting solution?

Answer 1

π=iMRT

Where, π is Osmotic pressure,
i=1 for non-electrolytes,
M is molar concentration of dissolved species (units of mol/L)
R is the ideal gas constant = 0.08206 L atm mol⁻¹K⁻¹,
T is the temperature in Kelvin(K),

Here, to calculate M convert into standard units mg tog, ml to L, c to Kelvin
M= ($\frac{35.8}{598}$ *10⁻³ )/ 0.175 =(5.987 *10⁻⁵)mol / 0.175L = 34.21*10⁻⁵ mol/L

π=iMRT=(1)*(34.21*10⁻⁵)*(0.08206)*(298.15)=837×10⁻⁵= 8.37×10⁻³ atm
=6.36 torr
(1 atm=760 torr, 1 Kelvin =273.15 °C, 1L=1000ml, 1g=1000mg)