Question

A complex is written as m(en)y.xbr. its 0.05 molar solution shows 2.46 atm osmotic pressure at 27°c. assuming 100% ionisation and coordination number of metal (iii) is six, complex may be (1) [m(en)2br2]br (2) [m(en)3]br3 (3) [m(en)2br]br2 (4) [m(en)]br3

Answer 1

Answer: $[m(en)_2Br_2]Br$

Explanation: Osmotic pressure is calculated by the formula:

$\pi =iCRT$ for electrolytes

$\pi$ = osmotic pressure  = 2.46 atm

i= vant hoff factor= no of ions produced on complete dissociation

C= concentration  = 0.05 M

R= solution constant= 0.0821 Latm\Kmol

T= temperature  =$27^0C=27+273=300K$

i= vant hoff factor

$2.46=i\times 0.05M\times 0.0821\times 300K$

$i=2$

Thus the given complex must produce 2 ions and the complex is written by  $m(en)_2Br_2]Br$ as it produces only two ions on dissociation.

$[m(en)_2Br_2]Br\rightarrow [m(en)_2Br_2]^++Br^-$

Answer 2

The vant-Hoff factor is 2 and since the coordination no. is 6 and n = 2 ; Formula is [M(en)2Br2]Br On ionization it forms two ions.