Mixtures

Mixtures A physical blend of more than TWO SUBSTANCES A physical blend of more than TWO SUBSTANCES There are TWO classifications of mixtures There are TWO classifications of mixtures HOMOGENEOUS HOMOGENEOUS HETEROGENEOUS HETEROGENEOUS

HOMOGENEOUS MIXTURES HOMO – From the Greek word meaning THE SAME HOMO – From the Greek word meaning THE SAME Completely uniform distribution Completely uniform distribution Each sample will contain the same proportions of the mixture Each sample will contain the same proportions of the mixture Solutions are examples of HOMOGENEOUS MIXTURES Solutions are examples of HOMOGENEOUS MIXTURES

SOLUTIONS Place salt in water Place salt in water Solid phase added to liquid phase Solid phase added to liquid phase Homogeneous? Homogeneous? YES! YES! The salt dissolves in the water leading to a UNIFORM DISTRIBUTION The salt dissolves in the water leading to a UNIFORM DISTRIBUTION Solutions can be gas/gas, liquid/gas, gas/liquid, liquid/liquid, solid/liquid and solid/solid Solutions can be gas/gas, liquid/gas, gas/liquid, liquid/liquid, solid/liquid and solid/solid

EXAMPLES G/G ? AIR G/G ? AIR L/G ? Water vapor in air (clouds - localized) L/G ? Water vapor in air (clouds - localized) G/L? Soda G/L? Soda L/L? Coffee/Tea L/L? Coffee/Tea S/L? anything that dissolves in water S/L? anything that dissolves in water S/S? Steel S/S? Steel

HETEROGENEOUS MIXTURES HETERO – From the Greek word meaning different HETERO – From the Greek word meaning different Not uniform in composition Not uniform in composition Oil and water Oil and water Heterogeneous? Heterogeneous? YES! YES! The oil will not mix with the water creating two phases The oil will not mix with the water creating two phases

A Phase? Any part of a system with uniform properties Any part of a system with uniform properties Homogeneous Mixtures consist of a single phase Homogeneous Mixtures consist of a single phase Heterogeneous mixtures consist of two or more phases Heterogeneous mixtures consist of two or more phases

Examples Lava Lamp – Water Phase/Wax Phase Lava Lamp – Water Phase/Wax Phase Soup – Liquid/Chunky Bits Soup – Liquid/Chunky Bits Burgers – Meat/Bread/Salad/Special Sauce Burgers – Meat/Bread/Salad/Special Sauce Your turn – Think of 3 more examples of heterogeneous mixtures Your turn – Think of 3 more examples of heterogeneous mixtures

Separating Mixtures Some mixtures are easily separated by simple physical means Some mixtures are easily separated by simple physical means Burger with no pickle – Just take out the pickle Burger with no pickle – Just take out the pickle Some mixtures may rely on physical properties to separate Some mixtures may rely on physical properties to separate

Lets think about a complex mixture Salt and water Salt and water Homogeneous Homogeneous Salt dissolved in the water Salt dissolved in the water What can we do to separate this mixture What can we do to separate this mixture Are there any physical properties we can make use of Are there any physical properties we can make use of

Salt and Water Water evaporates at much lower temperatures than salt Water evaporates at much lower temperatures than salt Heat the mixture Heat the mixture The water will evaporate, leaving the salt The water will evaporate, leaving the salt How could we recover the water? How could we recover the water?

Distillation Salt + Water Heat Liebig Condenser Water Water is evaporated by the heat Cooled and condensed in the condenser Collected in the beaker The salt will remain in the conical flask as a crystallized solid

More Distillation What else can we separate with distillation apparatus? What else can we separate with distillation apparatus? Mixtures of Liquids Mixtures of Liquids How? How? We use the physical property of BOILING POINT to separate different liquids We use the physical property of BOILING POINT to separate different liquids This type of distillation is called FRACTIONAL DISTILLATION This type of distillation is called FRACTIONAL DISTILLATION

Distillation Thermometer Salt + Water Condenser Collection Vessel Heat

Review Give five examples of the following: Give five examples of the following: 1. Pure substance 2. Homogeneous Mixture 3. Heterogeneous Mixture 4. Solution Outline a method for separating components from of your examples for 2, 3 and 4 Outline a method for separating components from of your examples for 2, 3 and 4

Other Separation Methods Chromatography Chromatography Liquid Liquid Ion Ion Size Exclusion Size Exclusion Precipitation Precipitation Solvent Extraction (filtration) Solvent Extraction (filtration)

DEMO Set up a CHROMATOGRAPHY Experiment from the handout Set up a CHROMATOGRAPHY Experiment from the handout Refer to the instructions for writing up a lab Refer to the instructions for writing up a lab PURPOSE – To see if ink is a mixture or a pure substance PURPOSE – To see if ink is a mixture or a pure substance Analysis and conclusions questions Analysis and conclusions questions What did you observe? What did you observe? How do we classify the ink? Is it a pure substance? How do we classify the ink? Is it a pure substance?