Water Potential Calculator
Ψ from solute and pressure potential for AP Biology.
Enter your values
sucrose = 1, NaCl = 2
Enter the molar concentration in M.
Enter the temperature in °C.
Enter the pressure potential ψp in bars.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- 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
At a glance
| What it does | Ψ from solute and pressure potential for AP Biology. |
|---|---|
| Category | Science |
| Inputs needed | Ionisation constant i, Molar concentration, Temperature, Pressure potential Ψp |
| Main output | Water potential Ψ |
| Formula | Ψ = Ψs + Ψp, Ψs = −iCRT |
| Cost | Free — no sign-up, no download |
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
- Molar concentration(M)
- Enter the molar concentration in M.
- Temperature(°C)
- Enter the temperature in °C.
- Pressure potential Ψp(bars)
- Enter the pressure potential ψp in bars.
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.
What do I need to enter into the Water Potential Calculator?
Just 4 values: ionisation constant i, molar concentration, temperature, pressure potential ψp. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Water Potential Calculator work out the answer?
Water potential Ψ is the sum of solute potential and pressure potential; water always moves from higher Ψ to lower Ψ. It applies the formula Ψ = Ψs + Ψp, Ψs = −iCRT and shows the working so you can check each step by hand.
Is the Water Potential Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.