Question

Osmotic pressure Π is given by the relation:Π = iMRTwhere i is the van’t Hoff factor, M is the concentration of solute, R is the gas constant, and T is the temperature. The osmotic pressure of sea water is approximately 24 atm at 25°C. What is the approximate concentration of salt in sea water (approximated by NaCl with i = 2)? (Note: Use R = 0.08 L•atm/mol•K.)

Answer 1

Answer: The concentration of solute is 0.503 mol/L

Explanation:

To calculate the concentration of solute, we use the equation for osmotic pressure, which is:

$\pi=icRT$

where,

$\pi$ = osmotic pressure of the solution = 24 atm

i = Van't hoff factor = 2 (for NaCl)

c = concentration of solute = ?

R = Gas constant = $0.08\text{ L atm }mol^{-1}K^{-1}$

T = temperature of the solution = $25^oC=[273+25]=298K$

Putting values in above equation, we get:

$24atm=2\times c\times 0.08\text{ L.atm }mol^{-1}K^{-1}\times 298K\\\\c=0.503mol/L$

Hence, the concentration of solute is 0.503 mol/L