Properties of Solutions. Copyright © Houghton Mifflin Company. All rights reserved. 17a–2 “Likes Dissolve Likes” substances with similar noncovalent forces

Properties of Solutions

Copyright © Houghton Mifflin Company. All rights reserved. 17a–2

“Likes Dissolve Likes”

• substances with similar noncovalent forces are likely to be soluble in each other

• solutes do not readily dissolve in solvents whose noncovalent forces are quite different from their own

• stronger solute-solvent attractions favor solubility, stronger solute-solute or solvent-solvent attractions reduce solubility


Solubilities of Some Alcohol

Copyright © Houghton Mifflin Company. All rights reserved.

Solution Terminology

saturated• solution containing undissolved solute in

equilibrium with the solutionunsaturated• solution containing less than the maximum

amount of solutesupersaturated• solution containing more solute than is

normally allowed


Types of Solutions


Supersaturated Solution


Henry's Law

Low pressure

Low concentration

Double the pressure equilibrium

Double the concentration

The solubility of a gas in a liquid depends on temperature, the partial pressure of the gas over the liquid, the nature of the solvent and the nature of the gas.


Cuba diving with trimixtrimix= oxygen, nitrogen and helium

Why one should dive deep dives with trimix?

1. Nitrogen narcosis can be avoided by replacing nitrogen with helium. Helium is not as narcotic as nitrogen.

2. By decreasing the percentage of oxygen in the mix, one can dive deeper without a danger of oxygen toxicity.

•Disadvantages of Helium:

•The best known effect of helium is its distortion of speech. The thinner gas passing across the vocal cords at atmospheric pressure produces a comical high-pitched squeak reminiscent of Donald Duck and family.

•There is an apparent chilling during breathing.


Henry’s Law

Sg = kHPg

where Sg solubility

kH Henry’s Law constant

Pg partial pressure

of gas


Henry’s Law


Solubility of Oxygen in Water


Solubility of Ionic Compounds and

Temperature


Water Dissolving An Ionic Solute


Hydration of a Sodium Ion


Comparison of Concentration Terms


Parts per Million

#g of solute #mg of solute

ppm = 106 =

#g of solution #kg of solution

#micro-L solute

ppm =

#Lof solution


Parts per Billion

#g of solute #micro-g of solute ppb = 109 =

#g of solution #kg of solution


Colligative Properties

• properties that depend on the number of particles not on the identity of the particles

Raoult’s Law

P1 = X1P1o

• vapor pressure lowering


Vapor Pressure ofPure Water vs. Sea Water


Solvent Freezing


Boiling Point Elevation


Boiling Point Elevation

T = Tfinal - Tinitial

(Tb = bpsolution - bppure solvent)

Tb = kb x m

where kb => boiling point elevation constant

m => molality of all solutes in solution


Freezing Point Depression

T = Tfinal - Tinitial

(Tf = fppure solvent - fpsolution)

Tf = kf x m

where kf => freezing point depression constant

m => molality of all solutes in solution


Osmosis


Osmotic Pressure

= cRTi

where => osmotic pressure

c => concentration

R => gas constant

T => absolute temperature

i => number of particles per formula unit


Colligative Propertiesof Electrolytes

vpwater > vp1M sucrose > vp1M NaCl > vp 1M CaCl2

1 mole sucrose = 1 mole molecules

1 mole NaCl = 2 mole of ions

1 mole CaCl2 = 3 moles ions

Documents

Properties of Solutions. Copyright © Houghton Mifflin Company. All rights reserved. 17a–2 “Likes Dissolve Likes” substances with similar noncovalent forces