Sea water is `3.5%`by mass of a salt and has a density `1.04gcm^(-3)` at `293K`.Assuming the salt to be sodium chloride ,calculate the osmotic pressure of sea water.Assume complete ionisation of the salt-

Options

A. 25.45 atm
B. 11.56 atm
C. 29.98 atm
D. 30.20 atm

Answer

C

Explanation

Let mass of solution be 100 g .
Volume of solution =`"Mass"/"Density"=100/1.04`=96.154 mL=0.096 L
`w_B`=3.5 g
`M_B =58.5 g mol^(-1)` (molar mass of NaCl)
For complete ionisation of NaCl, van't Hoff factor will be '2'.
i=2
we know,
`pi`=iCRT=`i n/V RT=2xx(3.5xx0.0821xx293)/(58.5xx0.096)`=29.28 atm