Understanding Osmotic Pressure
Osmotic pressure (OP) is the pressure required to prevent the flow of solvent into a solution through a semipermeable membrane. For non-electrolytes, the relationship between osmotic pressure and molarity can be described by the formula:
OP = iCRT
(where i = van 't Hoff factor, C = concentration, R = gas constant, T = temperature in Kelvin)
In this case, since it is a non-electrolyte, i = 1.
Given Data
- OP of 1M solution = 22.4 bar
- Molarity of new solution = 0.1M
Calculating Osmotic Pressure for 0.1M Solution
- Since osmotic pressure is directly proportional to molarity, we can establish the following relationship:
- For 1M solution: OP = 22.4 bar
- For 0.1M solution: OP = (0.1M / 1M) * 22.4 bar
- Thus, OP for 0.1M solution = 0.1 * 22.4 bar = 2.24 bar.
Calculating Water Potential (ψw)
Water potential (ψw) is defined as the potential energy of water in a system and is influenced by osmotic pressure (ψs). For dilute solutions, the water potential can be approximated as:
ψw = - OP
- Therefore, for the 0.1M solution:
- ψw = -2.24 bar
Conclusion
- The water potential (ψw) for a 0.1M solution of a non-electrolyte is -2.24 bar. This negative value indicates that the solution has a lower water potential compared to pure water, which has a ψw of 0 bar.