Question

A complex is written as M(en) .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)2BrJBr2

(4) [M(en)]Br3

Answer 1

P = iCRT

=> 2.46 = i*0.05*0.0821*300
=> i = 1.997 ≈ 2

derfore molecule dissociates into two parts.

So, the compd is of the type

[M(en)_xBr_y]Br

now 2x+y = 6 and y not equal to 0
=> y = 2/4

If y=2, x=2
So, complex is [M(en)₂Br₂]Br

or
if y=4,x=1
Then the complex is [M(en)Br₄]Br
Here only one complex matches the option.
ans) option 1