Answer:
The actual Van't Hoff factor for AlCl3 is 3.20
Explanation:
Step 1: Data given
Molarity of AlCl3 = 0.050 M
osmotic pressure = 3.85 atm
Temperature = 20 °C
Step 2: Calculate the Van't Hoff factor
AlCl3(aq) → Al^3+(aq) + 3Cl^-(aq)
The theoretical value is 4 ( because 1 Al^3+ ion + 3 Cl- ions) BUT due to the interionic atractions the actual value will be less
Osmotic pressure depends on the molar concentration of the solute but not on its identity., and is calculated by:
π = i.M.R.T
⇒ with π = the osmotic pressure = 3.85 atm
⇒ with i = the van't Hoff factor
⇒ with M = the molar concentration of the solution = 0.050 M
⇒ with R = the gas constant = 0.08206 L*atm/K*mol
⇒ with T = the temperature = 20 °C = 293.15 Kelvin
i = π /(M*R*T
)
i = (3.85) / (0.050*0.08206*293.15)
i = 3.20
The actual Van't Hoff factor is 3.20
