Calculate water potential from solute potential and pressure potential. Enter molarity to derive solute potential automatically using the van ‘t Hoff equation.
Calculate water potential from solute potential and pressure potential. Use this for osmosis and plant cell questions.
Ψ = Ψs + Ψp. For dilute solutions, Ψs ≈ −iCRT, where i is the ionisation constant (1 for sucrose/glucose, 2 for NaCl), C is molarity (mol/L), R = 0.008314 L·MPa/(mol·K), T is temperature in Kelvin (°C + 273).
Understanding water potential
Water potential (?) determines the direction water moves during osmosis. Water moves from higher ? (less negative) to lower ? (more negative). Pure water at standard pressure has ? = 0. Adding solute makes ? more negative. The total water potential is ? = ?s + ?p.