Water Potential.pdf - Calculation of Water Potential from...

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Calculation of Water Potential from Experimental Data The solute potential of a sucrose solution can be calculated usingthe following formula:Ψs= -iCRTi = Ionization constant (for sucrose this is 1.0 because sucroseis a sugar and does not ionize in water and for sodiumchloride this is 2.o)C = Molar concentrationR = Pressure constant (R = 0.0831 liter bars/mole °K)T = Temperature °K (273 + °C of solution)The units of measure will cancel as shown in the following example:If you have a 1.0 M sugar solution at 22 °C under standardatmospheric conditionsΨs= -i x C x R x TΨs= -(1) (1.0 mole/liter) (R = 0.0831 liter bars/mole °K) (295 °Ψs= -24.51 barsKnowing the solute potential of the solution (Ψs) and knowing thatthe pressure potential of the solution is zero (Ψp= 0) allows you tocalculate the water potential of the solution. The water potentialwill be equal to the solute potential of the solution.Ψ= 0 + Ψsor Ψ= Water potential values are useful because they allow us to predictK)Ψs

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