# Water Potential Problems HW.wanswers.docx - Name Period...

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Name: ______________________________________ Date: ________________Period _______Water Potential ProblemsThe solute potential (ψS) = – iCRT, where i is the ionization constant, C is the molar concentration, R is the pressure constant (R = 0.0831 liter bars/mole-K), and T is the temperaturein K (273 + °C).Example 1: A 0.15 M solution of sucrose at atmospheric pressure (ψP= 0) and 25°C.S) = – iCRTC= 0.15 MT= (273 +25)R= 0.0831i= 1 (this is because sucrose doesn’t disassociate in water)ψS= - (1)(0.15)(0.0831)(273+25) = -3.7 barsThis example has an osmotic potential of -3.7 bars Ψs+ Ψp= ΨΨ = 0 + -3.7 bars = -3.7 barsExample 2: A 0.15 M NaCl solution contains 2 ions, Na+and Cl-; therefore i = 2. Room Temperature of 25°C.S) = – iCRTi=2C= 0.15 MR= 0.0831T= (273 +25)S)= -(2)(0.15)(0.0831)(298) = -7.4 barsNext:Ψ = 0 + -7.4 bars =-7.4 barsCareful when answering these questions:Which of the above has MORE water potential?Example 1Which of the above is MORE concentrated?Example 2
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