Final answer:
The total water potential of a NaCl solution is found using the osmotic potential, which is calculated with the van't Hoff equation by considering the concentration of dissolved particles and temperature. Since the given concentration is 0.20 M and dissociates into two particles, we use 0.40 M for the calculation at 32°C, converting the final osmotic pressure into MPa.
Step-by-step explanation:
To find the total water potential of a NaCl solution, we must consider the osmotic potential because the pressure potential is given as zero. The osmotic potential (Ψs) is calculated using the van't Hoff equation, which relates the osmotic pressure (II) to solute concentration (M), the gas constant (R), and the temperature (T) in Kelvin. For NaCl, which dissociates completely into Na+ and Cl−, we have to account for both ions when determining the solute concentration. Thus, for a 0.20 M NaCl solution, we have a total of 0.40 M of dissolved particles in the solution.
Using the van't Hoff equation:
Ψs = -iCRT
Where i is the van't Hoff factor (which is 2 for NaCl), C is the molar concentration of dissolved particles (0.40 M), R is the gas constant (0.0821 L · atm/K · mol), and T is the absolute temperature (305 K for 32°C). Plugging these values in, we get:
Ψs = -(2)(0.40 mol/L)(0.0821 L · atm/K · mol)(305 K)
Before converting to MPa, we must remember that 1 atm is approximately equal to 0.101325 MPa. Thus, the solution's osmotic potential is:
Ψs = -(2)(0.40)(0.0821)(305)(0.101325).
The correct answer will be a negative value in MPa demonstrating water potential due to osmotic effects but without having the actual calculated value, an exact option (A-D) cannot be provided here as none of the given options can be verified to be correct with the information provided.