Question

100 ml of a solution of physiological saline (0.92% NaCl by weight) is diluted by the addition of 210 ml of water. what is the osmotic pressure of the final solution at 37 degrees Celsius? Assume that NaCl dissociates completely into Na+ and Cl-.

Answer 1

100 ml of a solution of physiological saline (0.92% NaCl by weight) is diluted by the addition of 210 ml of water. what is the osmotic pressure of the final solution at 37 degrees Celsius? Assume that NaCl dissociates completely into Na+ and Cl-.

Solution:

The final volume =210 mL

Amount of NaCl = 0.92% NaCl by weight , this means 0.92g in 100mL

So the moles of NaCl = Mass / Molar mass = 0.92 / 58.5 = 0.0157 moles

molarity = moles / Volume in L = 0.0157 / 0.210 = 0.0748 M

= iMRT

i =2

R = 0.0821 L atm / mol K

T = 310 K

= 2 X 0.0748 X 0.0821 X 310 = 3.81 atm