SOLUTIONS Chapter 12

solutions Homogeneous Particle size- atoms, ions, molecules Does not separate on standing Cannot be separated by filtration Does not scatter light

Colloids Heterogeneous Very large particles Does not separate on standing Cannot be separated by filtration Scatters light- Tyndal effect

Suspensions Heterogeneous Very large particles Particles settle out Can be separated by filtration May 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 dissolved Solvent- substance (medium) doing the dissolving

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

Random facts Water is the universal solvent Air is the solvent for all evaporated substances Alloy- mixture of 2 metals BRASS- zinc and copper 14 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 above 3. 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 O 2 (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--Hydrophobic Soap 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 water Soapy 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 solute Unsaturated- less than max amount of solute Supersaturated- 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 KNO 3 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 depression Boiling point elevation Adding solute will lower the freezing point of a solution Adding solute will raise the boiling point