Osmotic potential is calculated by applying the Morse equation, which relates the osmotic pressure of an ideal, low-concentration solution to the molarity of the solution and the absolute temperature. The equation involves the use of two vital physical constants: the universal gas constant and the van ‘t Hoff factor.
The first step in calculating osmotic potential usually involves the calculation of the solution molarity. The atomic masses of the individual atoms of the solute must be extracted from a periodic table. Next, the molar masses of the solutes must be calculated by arithmetically adding each of these atomic masses together based on the number of each atomic mass in the chemical formulae of the solutes. If a solute is not fully soluble in the solvent, this partial solubility must be factored into the final molar mass of the solution.
The absolute temperature is then calculated. Absolute temperature is equal to the temperature in Celsius plus 273.3. If the temperature is given in Fahrenheit, it must be converted to Celsius first. The van ‘t Hoff factor of the solute in the solvent must then be determined using tables.The van ‘t Hoff factor determines the degree of the dissociation of the solute in the solution. Finally, the osmotic pressure can be calculated by multiplying the absolute temperature by the van ‘t Hoff factor, the universal gas constant and the molarity.