SOLUTIONS

Chapter 12

solutions

HomogeneousParticle size- atoms, ions, moleculesDoes not separate on standingCannot be separated by filtrationDoes not scatter light

Colloids

HeterogeneousVery large particlesDoes not separate on standingCannot be separated by filtrationScatters light- Tyndal effect

Suspensions

HeterogeneousVery large particlesParticles settle outCan be separated by filtrationMay or may not scatter light

Electrolyte- a solution that conducts electricity—must have ions present

Remember- some ionic bonds dissolve to form electrolytes

What system in the body uses electrolytes?

Solute- substance being dissolvedSolvent- substance (medium) doing the

dissolving

Substances that are mutually soluble- the smaller amount is the solute

Random facts

Water is the universal solventAir is the solvent for all evaporated substancesAlloy- mixture of 2 metals

BRASS- zinc and copper14 carat gold- gold and silver

Foams and emulsions are colloids (mayo, shaving cream)

What type of mixture is Fog? What is fog made of?

Why do you drive with your lights on dim?

Increase Rate of dissolving

1. heat- particles collide faster and more often

2. agitation- same as above3. surface area- more area exposed to the solvent (crushing, grinding)

solubility

Amount of solute that can be dissolved in a specific amount of solvent

Formation of a solution

Solute breaks apart (endo)Solvent breaks apart (endo)Solute and solvent form and attraction(exo)Overall depends on which is greater- exo or

endo

Solubility of a substance depends on: bonding, pressure, temperature.

Bonding effect

Like dissolves like Polar dissolves polar Nonpolar dissolves nonpolar Review terms: miscible, immiscible

Why can oxygen gas O2 (nonpolar) dissolve in water (polar)? (This is an IMF question)

Why drink red wine with red meat?

Red meat is very fatty and this fat coats the tongue

When the skin of the grape undergoes fermentation, tannic acid is produced

Tannic acid has a polar end and a nonpolar end. The nonpolar end dissolves the fat off of the tongue

White wine(no grape skins) does not contain tannic acid, has a milder taste and is used with low fat meat(chicken)

Can I drink Welch’s grape juice and get the same effect as red wine?

Soap and detergent

Soap and Detergent

Water is polar - Hydrophilic Grease is nonpolar--HydrophobicSoap is a long carbon chain compound that

has a polar end and a nonpolar end.Nonpolar end sticks into the grease and the

polar end can dissolve in waterSoapy water forms a colloid and is washed

down the drain

Soaps form precipitates with “hard water”. Water that contains ions such as Ca+2, Fe+3

Detergents do not form precipitates so they wash away cleaner

Pressure

Effects gases Increase in pressure, increases solubility of gas Decrease in pressure, decreases solubility of gas Effervescence- rapid escape of a gas

Why do you tap on the mouth of a coke can?

What is the “bends” to a scuba diver?

A diver will have more gases dissolved in their blood. A diver has to pause when coming up to allow for the gases to be exhaled. Too fast ascent and the gases cannot be exhaled

Read page 368

Temperature

Increase in heat– increases solubility of a solid and liquid

Decrease in heat- increases solubility of a gas

Which goes flat faster? A opened Coke in the refrigerator or the coke left on

the counter

What is thermal pollution in a lake? Why does it kill fish?

Boiling water Boiling occurs when the atmospheric pressure is

equal to the vapor pressure Bubbles at the bottom of beaker- what are they and

why did they appear? Why are cake recipes altered for higher atmospheric

regions

Concession Stands

Trailer type- no electricity- how does the carbon dioxide get dissolved in the drinks?

Resturant type- has electricity- how does the carbon dioxide get dissolved in the drinks?

Saturated- max amount of soluteUnsaturated- less than max amount of soluteSupersaturated- using heat, the solute was

dissolved and the solution was slowly cooled- contains more than the max amount of solute at the lower temperature.

Solubility curve

What temperature is needed to dissolve 50 grams of potassium nitrate in 100 ml?

How many grams of potassium chloride is needed to make a saturated solution at 80c?

If a saturated solution was made at 80c of KNO3 and cooled to 40c. How many grams of solute came out of solution when a seed crystal was added? What is the solution called at 40 c?

Looking at the graph, which substance is a gas based on the solubility graph?

Which substance has the highest solubility at 10c?

What 2 substance has the same solubility at 72c?

Expressing Concentration

Molarity Moles of solute/ Liters of solution

Molality Moles of solute/kg of solvent

% concentration

Colligative properties

Properties that depend on the concentration of the solute particles and NOT their identity

Freezing point depressionBoiling point elevation

Adding solute will lower the freezing point of a solution

Adding solute will raise the boiling point