Question

Place the following aqueous solutions of nonvolatile, nonionic compounds in order of decreasing osmotic pressure.

a). 0.011 m 1-propanol
b) 0.00095 m sucrose
c) 0.0060 m glycerin
d)0.011 m 1-propanol

Answer 1

To order solutions by osmotic pressure, we use the van 't Hoff factor to determine effective molarity. The solution with the highest effective molarity (from dissociation into ions) will have the highest osmotic pressure. Therefore, the order is 0.1 M CaCl2, 0.07 M Ga(C2H3O2)3, 0.05 M MgBr2, and 0.1 M HCl.

Step-by-step explanation:

To order aqueous solutions by osmotic pressure, we must consider the van 't Hoff factor, which indicates the number of particles into which a compound dissociates in solution. For ionic compounds that dissociate into multiple ions, the osmotic pressure will be higher for solutions of the same molarity. The order can be determined by both the molarity and the number of particles produced upon dissolution.

1. 0.1 M CaCl2 (produces 3 particles: 1 Ca2+ + 2 Cl-, effective concentration 0.3 M)
2. 0.05 M MgBr2 (produces 3 particles: 1 Mg2+ + 2 Br-, effective concentration 0.15 M)
3. 0.07 M Ga(C2H3O2)3 (produces 4 particles: 1 Ga3+ + 3 C2H3O2-, effective concentration 0.28 M)
4. 0.1 M HCl (produces 2 particles: 1 H+ + 1 Cl-, effective concentration 0.2 M)

For the given solutions, the order of decreasing osmotic pressure is CaCl2, Ga(C2H3O2)3, MgBr2, and then HCl, based on the effective molarity when considering the dissociation into ions.