Ask Your Teacher Calculate the freezing-point depression and osmotic pressure in torr at 25°C for an aqueous solution of 3.2 g/L of a protein (molar mass = 9.0 ✕ 104 g/mol) if the density of the solution is 1.0 g/cm3

Respuesta :

Answer:

Osmotic pressure(π) = 0.661 Torr.

Depression in freezing point =  6.64 * 10⁻⁵ °C.

Explanation:

To calculate depression in freezing point and osmotic pressure, let's start by calculating Molarity of the solution.

Also, protein undergoes no dissociation or association when in solution.

Molarity = [tex]\frac{Moles of solute}{liters of solution}[/tex]

Molarity = [tex]\frac{3.2 g/L}{9.0 * 10^{4}g/mol }[/tex]

Molarity= 3.56 * 10⁻⁵ mol/L

Temperature = 25 +273 = 298 K

Osmotic pressure(π) = M R T

= (3.56 * 10⁻⁵ mol/L)* (0.08206 L atm/ mol K) * (298 K)

= 87.055 *  10⁻⁵ atm

But 1 atm= 760 Torr

So, Osmotic pressure(π) = (87.055 *  10⁻⁵ atm) * ( 760 torr/ 1atm)

= 0.661 Torr.

The depression in freezing point Δ[tex]T_{f} =K_{f} * m[/tex]

[tex]K_{f}[/tex]= molal freezing point depression constant of the solvent (1.86 °C/m for water).

m= molality or molal concentration of the solution.

m= moles of solute in 1kg of solvent.

Density of solution = [tex]1.0 \frac{g}{cm^{3} }[/tex]

Mass of 1L(1000 cm³) of this solution is= density * volume of solution

= 1000g

Molarity means 3.56 * 10⁻⁵ mol of protein in 1L of solution

Mass of protein=  3.56 * 10⁻⁵ * 9.0 * 10⁴ = 3.2 g of protein

1000g of solution- 3.2 g of protein = 996.8 g of solvent

Molality =  [tex]\frac{3.56 * 10⁻⁵ mol}{0.9968 kg}[/tex]

=3.57 *  10⁻⁵ m

depression in freezing point Δ[tex]T_{f} =K_{f} * m[/tex]

= 1.86 * 3.57 *  10⁻⁵ = 6.64 * 10⁻⁵ °C.