Question

Osmosis is the process responsible for carrying nutrients and water from groundwater supplies to the upper parts of trees. The osmotic pressures required for this process can be as high as 19.6 atm. What would the molar concentration of the tree sap have to be to achieve this pressure on a day when the temperature is 32°C ?

Answer 1

Answer: Molar concentration of the tree sap have to be 0.783 M

Explanation:

To calculate the concentration of solute, we use the equation for osmotic pressure, which is:

$\pi=iCRT$

where,

$\pi$ = osmotic pressure of the solution = 19.6 atm

i = Van't hoff factor = 1 (for non-electrolytes)

R = Gas constant = $0.0821\text{ L.atm }mol^{-1}K^{-1}$

T = temperature of the solution = $32^oC=[273+32]=305K$

Putting values in above equation, we get:

$19.6atm=1\times C\times 0.0821\text{ L.atm }mol^{-1}K^{-1}\times 305K$

$C=0.783M$

Thus the molar concentration of the tree sap have to be 0.783 M to achieve this pressure on a day when the temperature is 32°C