Question

The water potential of pure water is zero. If it is converted into a solution of 0.1 M concentration, the water potential

• A. Remains unchanged
• B. Is decreased by 0.1%
• C. And solute potential is increased by 2.3 bars
• D. Decreases by 2.3 bars

Answer 1

The correct option is D Decreases by 2.3 bars

Water potential of pure water at normal pressure and temperature is zero. Water potential is equal to the solute potential of the solution. Water potential is calculated by the formula, water potential = -iCRT

Where i = ionization constant

C = Molar concentration

R = Pressure constant = 0.0831 liter bar/mole K

T = Temperature in degrees Kelvin = 273 ${}^o$C

Thus, water potential of 0.1 M solution is -1 x 0.1 x 0.0831 x 273 = -2.3 bars.

Thus, the correct answer is option D.