Chapter 22 Notes Solutions

Chapter 22 Notes

SolutionsSection 1

SolutionsA mixture that appears the same throughout

and is mixed at the HOMOGENOUS levelSOLUTE=substance being dissolvedSOLVENT=substance doing the

dissolvingSolutions can be liquids, gases, or SOLIDS

(example:alloys)

Soda?Steel?

Trail mix?Salt water?

Italian salad dressing?

Are these examples homogenous?

How dissolving happens…Water molecules are POLAR. What does polar mean?Water molecules cluster around SOLID molecules, with their

negative ends attracted to the positive ends of the solidsWater molecules then PULL the solid particles into solutionThe moving WATER molecules and SOLID molecules spread out and

mix evenly to form a SOLUTIONHow do you think we mix solids to form alloys?• You must heat them!

StirringCrystal Size• Dissolving occurs at the

SURFACE of a solid.• Breaking a solid into pieces

increases its SURFACE AREA

Temperature• INCREASING the temp. of a

solvent speeds up the movement of its particles

• To make a gas dissolve more quickly in a liquid, COOL the liquid solvent and INCREASE the pressure of the gas

Rate of dissolving

depends on:

Chapter 22 Notes

Solubility and Concentration

Section 2

The amount of a substance that can dissolve in a solventSolubility

1. Depends on the nature of the SUBSTANCES

2. Solubilities of two substances can be compared by DISSOLVING BOTH IN WATER

Concentration Co

ncen

trate

d So

lutio

n Has a large amount of solute in the solvent

Dilu

te S

olut

ion

Has a small amount of solute in the solvent

Is expressed as percent by VOLUME of the solute

There are 3types of Solutions

1. Saturated SolutionContains all of the solute it can hold at a

given temperature• As the temperature of a liquid solvent increases, the

amount of solid solute that can dissolve in it INCREASES.• SOLUBILITY CURVE-line on a graph used to figure how

much solute can dissolve at any temperature on the graph.

Unsaturated SolutionAble to dissolve more solute at a given temperature

Supersaturated SolutionContains more solute than a saturated one at

the same temperature. How could this happen?• Made by INCREASING temp. of a saturated solution, adding more

solute, and lowering the temp back without RE-CRYSTALLIZING the solution

• SUPERSATURATED SOLUTIONS will crystallize if disturbed• As it crystallizes, it gives off ENERGY and produces heat.

Particles in Solution

Section 3

Electrolytes• Compounds that form

charged particles (ions) and conduct electricity in water

Nonelectrolytes• Substances that do not

ionize (form charged particles) in water and cannot conduct electricity

Ions: Particles with a charge

How IONS form…1. Molecules break apart in water causing

atoms to become ions by taking on a charge (IONIZATION)

2. Then, an ionic solid separates into its positive and negative ions (DISSOCIATION)

Effects of solute particles

1.All solute particles-polar, nonpolar, electrolyte, and nonelectrolyte-affect the PHYSICAL properties of the solvent

2.Adding a solute to a solvent LOWERS the freezing point because the added solute particles interfere with the formation of the orderly freezing pattern

3.Adding a solute RAISES the boiling point because fewer solvent molecules can reach the surface and evaporate

Dissolving without Water

Section 4

Do nonpolar molecules have a positive end and a negative end?

NO!!So, how do they dissolve solutes?

Nonpolar Dissolving1. They are NOT attracted to the polar water

molecules, so they do not DISSOLVE easily in water.

2. Example: NONPOLAR SOLUTES contain hydrocarbonsa)Large molecules of CARBON and hydrogen

atomsb)These atoms share ELECTRONS in an equal

manner, so there is no positive or negative charge (nonpolar)

Useful Nonpolar Molecules

Nonpolar solvents dissolve NONPOLAR solutes

Many nonpolar solvents are TOXIC (dangerous to touch or inhale)

Soap-used for washing because it has POLAR and NONPOLAR properties.

B vitamins and vitamin C are POLAR-dissolve in the WATER in your body cells.

Vitamin A is NONPOLAR-dissolves in the FAT of some body cells.

Polarity and Vitamins