Question

(a) Define the terms osmosis and osmotic pressure. Is the osmotic pressure of a solution a colligative property? Explain.
(b) Calculate the boiling point of a solution prepared by adding `15.00g` of `NaCl` to `250.0g` of water. (`K_(b)` for water `=0.512K kg "mol"^(-1)`, Molar mass of `NaCl=58.44g`)

Answer 1

(a) Osmosis : The spontaneous flow of solvent molecules from a less concentrated solution to a more concentrated solution though semi permeable membrane.
Osmotic pressure: The minimum excess pressure that has to be applied on the solution to prevent the entry of solvent into the solution through SPM.
It is a colligative property becuase it depends upon, no. of solute particles not on the . nature of particle. e.g., o. IMKCl and Na Cl has same osmotic pressure under same ten1p and pressure condition.
(b) (b) Elevation is boiling point
`[i=2" as " NaClhArrNa^++Cl]`
`DeltaT_b=(K_bxx1000xxW_B)/(W_AxxM_B)=(0.512xx1000xx15xx2)/(250xx25.44)=(512xx2)/974=1.051k`
Boiling point of water = 373 k
`373+1.051=374.051 k`