Water Potential Calculator
Ψ from solute and pressure potential for AP Biology.
Enter your values
sucrose = 1, NaCl = 2
ⓘ Live results
Results
- Water potential Ψ
- -3.715 bars
- Solute potential Ψs
- -3.715 bars
- Pressure potential Ψp
- 0 bars
- Water moves
- Into this solution (it is more negative)
Quick answer
Water potential Ψ is the sum of solute potential and pressure potential; water always moves from higher Ψ to lower Ψ.
Ψ = Ψs + Ψp, Ψs = −iCRT
How to use the Water Potential Calculator
- 1Enter the ionisation constant for your solute.
- 2Enter molarity and temperature in °C.
- 3Add pressure potential if the cell is turgid.
Inputs explained
- Ionisation constant i
- sucrose = 1, NaCl = 2
Worked example
Using the values the calculator loads with:
Inputs
- Ionisation constant i1
- Molar concentration0.15 M
- Temperature25 °C
- Pressure potential Ψp0 bars
Results
- Water potential Ψ-3.715 bars
- Solute potential Ψs-3.715 bars
- Pressure potential Ψp0 bars
- Water movesInto this solution (it is more negative)
Frequently asked questions
What is R in the water potential formula?
The pressure constant 0.0831 litre·bar per mole·kelvin used in AP Biology.
Why is solute potential negative?
Dissolved particles lower the free energy of water, so adding solute always reduces water potential.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.