Question

urea is the product of protein metabolism in mammals. what is the osmotic pressure of an aqueous solution containing 1.10g of urea in 100ml of solution at 20c

Answer 1

Answer:

The osmotic pressure of an aqueous solution containing 1.10g of urea in 100ml of solution at 20°C, is 4.4 atm.

Explanation:

Osmotic pressure is given by

       $\Pi = iMRT$

            where   i = van 't Hoff factor of the solute

                       M = molar concentration in mol/L

                        R = universal gas constant = 0.08206 L·atm/mol·K

                        T = absolute temperature in K

• Find Molar concentration of urea ,NH₂CONH₂

  Molar mass of urea= 14×2 + 12 + 16 + 4×1 = 60 g/mol

          moles of urea = mass of urea / molar mass of urea

⇒                                = 1.1 / 60 = 0.0183 mol

$Molar \;concentration\; of \;urea =\frac{number\;of moles\; of \;urea}{volume \;of \;solution}$

⇒                                             $=\frac{0.0183 \times 1000mL}{100mL \times 1L } = 0.183 mol/L$

• Find absolute temperature

                T =  °C + 273 = 20 + 273 = 293 K

Urea is not an electrolyte, it neither dissociates nor associates. Thus Van't Hoff factor is unity.

⇒              i = 1

• Find osmotic pressure

              $\Pi = iMRT$

⇒                = 1 × 0.183 × mol/L x 0.08206 L·atm/mol·K x 293 K

⇒                   = 4.399 ≈ 4.4 atm.

The osmotic pressure of urea solution is 4.4 atm