MIXTURES & SOLUTIONS Chapter 8

TYPES OF MIXTURES

HETEROGENEOUS MIXTURES  Definition – combination of 2 or more pure substances in which each pure substance retains its individual chemical properties.  Do not blend smoothly throughout.  Two types – Suspension & Colloid

HETEROGENEOUS MIXTURES Colloids  Intermediate size particles  Do not settle out when left standing  Concentrated colloids appear cloudy or opaque while dilute colloids appear to be solutions  Ex – milk, mayonnaise Suspensions  Largest size particles  Particles do settle out when left standing or can be separated by filtering  Ex – muddy water

HOMOGENEOUS MIXTURES  Also called solutions  Definition – combination of 2 or more pure substances in which each pure substance retains its individual properties; appears to be made up of only 1 thing though, you cannot tell the difference between the substances that make up a solution

SOLUTION VS. COLLOID  Both appear to be made up of only 1 thing.  Particles in a colloid scatter light when a beam of light is passed through the material (called the Tyndall effect).

SOLUTION VOCABULARY  Solute – Substance that IS dissolved in a solution.  Solvent – Substance that DOES the dissolving in a solution  Soluble – Ability to dissolve  Insoluble – Does not dissolve

SOLUTION VOCABULARY  Miscible – Two liquids able to dissolve in each other. Ex – water & vinegar  Immiscible – Two liquids that ARE NOT able to dissolve in each other. Ex – oil & water

FACTORS AFFECTING SOLVATION 14.3

SOLVATION  Definition – The process of surrounding solute particles with solvent particles to form a solution  For solvation to occur, the solute particles must separate from each other and interact with the solvent particles.  General rule used to predict if solvation will occur – “Like Dissolves Like”  This means that nonpolar molecules will dissolve nonpolar molecules (oil and gas)  Polar molecules will dissolve other polar molecules (salt and water)  Water is called the universal solvent because so many things can be dissolved in it.

NONPOLAR POLAR “Like Dissolves Like”

FACTORS AFFECTING SOLVATION  Molecules are constantly in motion according to the Kinetic Theory of matter  When particles collide, energy is transferred

FACTORS AFFECTING SOLVATION  Solubility = amount of a substance that will dissolve in a liquid  Smaller pieces of a substance dissolve faster b/c of larger surface area (decrease surface area)  Stirring or shaking speeds dissolving b/c particles are moving faster and colliding more  Heating speeds dissolving

SOLUBILITY SATURATED SOLUTION no more solute dissolves UNSATURATED SOLUTION more solute dissolves SUPERSATURATED SOLUTION becomes unstable, crystals form concentration

SOLUBILITY & TEMPERATURE  Unsaturated Solution – contains less dissolved solute for a given temperature, add more solute to a solution, if it dissolves, the solution was unsaturated  Saturated Solution – contains the maximum amount of dissolved solute for a given temperature, add more solute to a solution, if the added solute does not dissolve, the solution was saturated  Supersaturated Solution – contains more dissolved solute for a given temperature than it should, typically formed by cooling a saturated solution very slowly, very unstable

SOLUBILITY & TEMPERATURE  Typically, most solids become MORE soluble as the temperature of the solvent is increased (you can dissolve more sugar into hot water than cold water)  A few solids become LESS soluble as the temperature of the solvent is increased.  Gases become LESS soluble as the temperature of the solvent is increased.  A warm/hot soda seems more “gaseous” than a cold soda

SOLUBILITY  Solubility Curves  maximum grams of solute that will dissolve in 100 g of solvent at a given temperature  varies with temp  based on a saturated solution

SOLUBILITY Solubility Curve Solubility Curve  shows the dependence of solubility on temperature  Notice that most solids become more soluble when the temperature increases.

SOLUBILITY Solids are more soluble at... Solids are more soluble at...  high temperatures.  Gases are more soluble at... low temperatures & high pressures (Henry’s Law). EX: soda

SOLUBILITY 1)How many grams of NaCl are required to make a saturated solution at 30 o C? 2)Which solid’s solubility in water DECREASES as the temperature increases? 3)At what temp 110g of KNO 3 form a saturated solution in water?

SOLUBILITY 1)How many grams of NH 4 Cl are required at 90 o C to form a saturated solution? 2)What type of solution is made by dissolving 75g of KNO 3 in water at 60 o C? 3)What type of solution is made by dissolving 20g of KClO 3 in water at 50 o C?

Miscible substances are: A.two liquids that are not soluble in each other B.solids that dissolve in liquids C.solids that do not dissolve in liquids D.two liquids that are soluble in each other

When dispersed solids in a colloid scatter light, it is known as ____. A.Tyndall effect B.Brownian motion C.Henry’s law D.Charles’s law

A Sugar-water solution is made. More sugar is added to the solution, the solution is stirred and the added sugar DOES dissolve. What type of solution is this? A.solvated B.saturated C.supersaturated D.unsaturated

Which is NOT a type of solution? A.saturated B.unsaturated C.polyunsaturated D.supersaturated

Solutes in a solution can be: A.liquids only B.liquids and solids only C.gases and solids only D.gases, liquids, or solids

For a given amount, which type of solution contains the LEAST amount of solute? A.solvated B.saturated C.supersaturated D.unsaturated

A Sugar-water solution is made. More sugar is added to the solution, the solution is stirred and the added sugar DOES NOT dissolve. What type of solution is this? A.solvated B.saturated C.supersaturated D.unsaturated