A 1% (mass/vol) KCl solution is ionised to the extent of 80%. The osmotic pressure at `27^(@)`C of the solution will be :

Options

A. 2.64 atm
B. 5.94 atm
C. 26.4 atm
D. 59.4 atm

Answer

B

Explanation

1 % solution of KCI means 1kg KCI is present in 100 mL of solution.
Molarity = ` ("moles of solute" xx 1000) /( "volume of solution") `
` = ( 1xx 1000) /( 74.5 xx 100 ) = 0.134 M `
Now, `pi = CRT `
` = 0.134 xx 0.0821 xx 300 `
` therefore pi = 3.30 atm `
i = ` ("effective particles")/("original particles") `
` = ("observed osmotic pressure")/("calculated osmotic pressure") `
` ( 1 + 0.8 ) /( 1 ) = ( "observed osmotic pressure")/(3.30 ) `
` therefore ` Observed osmotic pressure ` = 1.8 xx 3.30 = 5.94` atm