What is the concentration (in Molarity) of an aqueous sodium chloride solution having on osmotic pressure of 22 atm at 18°C?

Answer 1

 use this equation

.. P osmotic = i * M * R * T

solving for M

.. M = P osmotic / (i * R * T)

.. ..  = 22 atm / (2 * 0.08206 Latm/molK * 291.15K) = 0.46M

Answer 2

(22 atm) / (18 + 273) K / (0.082057366 L atm/K mol) = 0.9213 mol/L ions

NaCl ⇌ Na{+} + Cl{-}  [two ions]

Supposing complete dissociation:

(0.9213 mol/L ions) x (1 mol NaCl / 2 mol ions) = 0.46 mol/L NaCl