Question

7. Which of the following solutions is isotonic (no osmosis) with a 0.30 M NaNO, solution? {hint - Find the osmosis molarity or "osmolarity" = (# ions)M} a) 0.10 M CaCl2 b) 0.30 M glucose c) 0.60 M NaCl d) 0.15 M AICI; e) 0.75 M KCI (n-1 for glucose) 8. If a solution of 0.20 M Mg(NO3)2 is separated from a 0.25 M KCl solution by a membrane that is permeable to water, osmosis will occur. Describe the osmotic flow. (What is flowing? In which direction?) 0,2x30.6.

Answer 1

Q -7 ) Osmolarity of NaNO₃ = number of ions x Molarity = 2 x 0.3 = 0.6 M

solution that have same osmolarity are isotonic means there is no net flow of solvent molecules.

we have to check osmolarity of all the given options

( a ) 3 x 0.1 = 0.3

( b ) 1 x 0.3 = 0.3

( c ) 2 x 0.6 = 1.2

( d ) 4 x 0.15 = 0.6

( e ) 2 x 0.75 = 1.5

So correct option is ( d )

Q-8 ) osmolarity of magnesium nitrate solution = 3 x 0.2 = 0.6

osmolarity of potassium chloride solution = 2 x 0.25 = 0.5

so magnesium nitrate solution is hypertonic while potassium chloride solution is hypotonic.

Flow of solvent is from hypotonic toward hypertonic.

So water molecules will flow from KCl solution towards magnesium nitrate solution.