Question

What mass of sucrose (C12H22O11) should be combined with 505g of water to make a solution with an osmotic pressure of 8.50atm at 285K ? (Assume the density of the solution to be equal to the density of the solvent.)

m = ? g

Answer 1

The osmotic pressure of a dilute solution ?=MRT

R= 0.0821 L atm/K mol is the gas constant

T = temperature = 285K

? = 8.50atm

M = molarity of the soluion.

By putting these values in the above equation we get M = 0.363 mol/L

Molar mass of sucrose = 342.2965 g/mol

So, in one liter of solution sucrose present = (342.2965 g/mol) X (0.363 mol/L)= 124.254 g

So, in 505g (505 mL, as density of solution = 1g/mL)of water sucrose present = 62.748 g.

62.748 g. mass of sucrose (C₁₂H₂₂O₁₁) should be combined with 505g of water to make a solution with an osmotic pressure of 8.50atm at 285K.