Consider separate solution of `0.500M C_(2)H_(5)OH(aq), 0.100M Mg_(3)(PO_(4))_(2)(aq), 0.250M KBr(aq)` and `0.125 M Na_(3)PO_(4)(aq)` at `25^(@)C`. Which statement is true about these solutions, assuming all salts to be strong electrolytes?

Options

A. `"0.500 M "C_(2)H_(5)OH (aq)` has the highest osmotic pressure
B. They all have the same osmotic pressure
C. `"0.100 M "Mg_(3)(PO_(4))_(2)` has the highest osmotic pressure
D. `"0.125 M "Na_(3)PO_(4)(aq)` has the highest osmotic pressure

Answer

B

Explanation

Osmotic pressure for electrolytes, `pi=iCRT`
`pi(C_(2)H_(5)OH)=1xx0.5RT=0.5RT,`
`pi(Mg_(3)(PO_(4))_(2))=5xx0.100RT=0.5RT`
`pi(KBr)=2xx0.25RT=0.5RT,`
`pi(Na_(3)PO_(4))=4xx0.125RT=0.5RT`
Thus, all solution have the same osmotic pressure.