Question

Which of the following solutions would have the highest osmotic pressure?

a) 0.35 m CH4N2O

b) pure water

c) 0.15 m Zn(CH3COO)2

d) 0.10 m Cr2(SO4)3

e) 0.16 m BaI2

Answer 1

Option d. 0.10 m Cr₂(SO₄)₃

Step-by-step explanation:

Formula for the osmotic pressure is determined as:

π = M . R . T . i

So you have to take account the i (Van't Hoff factor, numbers of ions dissolved)

• CH₄N₂O → 0.35 m

Urea is an organic compound, so the i value is 1

• H₂O → The i is also 1

• Zn(CH₃COO)₂ → 0.15 m

Zync acetate can be dissociated:

Zn(CH₃COO)₂ → 1Zn²⁺ + 2CH₃COO⁻

In this case, the i is 3. (you see, the stoichiometry of ions)

Cr₂(SO₄)₃ → 0.10 m

Chromium sulfate is dissociated:

Cr₂(SO₄)₃ → 2Cr³⁺ + 3SO₄⁻²

i = 5

BaI₂ → 0.16 m

BaI₂ → 1Ba²⁺ + 2I⁻

i = 3