Question

Which of the following solutions would have the highest value for osmotic pressure? (Assume each solution has water as the solvent and are at the same temperature.) A. 0.20 M NaCl B. 0.10 M CaCl2 C. 0.50 M CH3OH D. 0.30 M CaCl2 E. 0.10 M CH3COCH3

Answer 1

P = i*C*R*T
So greter the product of i and C , graeter will be the osmotic pressure
A. 0.20 M NaCl
i=2 Na+ and Cl-
C = 0.20 M
i*C= 2*0.20 = 0.40

B. 0.10 M CaCl2
i=3 ( Ca2+ and 2 Cl-)
C = 0.10 M
i*C= 3*0.10 = 0.30

C. 0.50 M CH3OH
i=1 since it won't dissociate
C = 0.50 M
i*C= 1*0.50 = 0.50

D. 0.30 M CaCl2
i=3 ( Ca2+ and 2 Cl-)
C = 0.30 M
i*C= 3*0.30 = 0.90

E. 0.10 M CH3COCH3
i=1 since it won't dissociate
C = 0.10 M
i*C= 1*0.10 = 0.10

i*C is maximum for D. 0.30 M CaCl2
So Answer is:
D. 0.30 M CaCl2