Wastewater discharged into a stream by a sugar refinery contains 3.40 g of sucrose (C12H22O11) per liter. A government-industry project is designed to test the feasibility of removing the sugar by reverse osmosis. What pressure must be applied to the apparatus at 20.°C to produce pure water?

Respuesta :

Answer: The pressure that must be applied to the apparatus is 0.239 atm

Explanation:

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

[tex]\pi=iMRT[/tex]

or,

[tex]\pi=i\times \frac{m_{solute}}{M_{solute}\times V_{solution}\text{ (in L)}}}\times RT[/tex]

where,

[tex]\pi[/tex] = osmotic pressure of the solution

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

[tex]m_{solute}[/tex] = mass of sucrose = 3.40 g

[tex]M_{solute}[/tex] = molar mass of sucrose = 342.3 g/mol

[tex]V_{solution}[/tex] = Volume of solution = 1 L

R = Gas constant = [tex]0.0821\text{ L atm }mol^{-1}K^{-1}[/tex]

T = temperature of the solution = [tex]20^oC=[20+273]K=293K[/tex]

Putting values in above equation, we get:

[tex]\pi =1\times \frac{3.40g}{342.3g/mol\times 1}\times 0.0821\text{ L. atm }mol^{-1}K^{-1}\times 293K\\\\\pi =0.239atm[/tex]

Hence, the pressure that must be applied to the apparatus is 0.239 atm