Do Now & Agenda Turn in Beer’s Law Lab if you did not do so last class Work on “Chem Phys Properties” Today: Chemical and Physical Properties: get stamped Separation Techniques Plan Separation Challenge Unit 2 Test FRI 10/21 (B), MON 10/24 (A) All missing work, corrections, and extra credit due by Test Day!

Definitions Physical Property=a property of matter that can be measured or observed without changing the chemical composition of the substance Ex: mass, melting and boiling point, Solubility (ability to dissolve in something)

Definitions Chemical Property=a property of matter that can only be measured or observed by changing the chemical composition of the substance Ex: Flammability Reactivity (whether the substance reacts with another substance)

Practice Identify the following as either physical properties (P) or chemical properties (C) 1. ____blue color 2. ____density 3. ____solubility 4. ____reacts with acid 5. ____volume 6. ____melting point 7. ____reacts with water to form a gas 8. ____hardness P P P C P P C P

Intensive vs. Extensive Properties Intensive Property: does NOT depend on how much of the substance there is Extensive Property: depends on how much of the substance there is

Recall… Mixture=a combination of 2 or more substances that you can physically separate into their individual parts without changing what they are. Mixtures can be separated based on their physical properties (ex: boiling point, solubility, size)

Filtration *separation based on different state of matter or particle size a technique that allows you to separate a heterogeneous mixture by catching the solid (undissolved particles) on the filter

Filtration

Filtration Examples Around the House

Evaporation takes advantage of differences in boiling point can be used to separate homo- or heterogeneous mixtures Downside: liquid components of mixture are lost to air through evaporation

Distillation takes advantage of differences in boiling point can be used to separate homogeneous or heterogeneous mixtures Superior method to evaporation because all components can be isolated and retained. The liquid with the lower boiling point collects in this flask Mixture of 2 liquids is placed in a flask over a heat source. The liquid with the higher boiling point stays in this flask

Centrifuge Separates a mixture based on differences in density Amount of separation depends on speed of centrifuge Must be followed by filtration or decanting Separates heterogeneous mixtures only!

Decanting Takes advantage of differences in states of matter and/or density A crude separation technique for heterogeneous mixtures.

Chromatography Chromatography is a technique that allows you to separate a homogeneous mixture based on size and polarity *polarity = level of attraction towards another substance Separate Mixture Components

How Chromatography Works   Chromatograhy paper Developing chamber Place TLC plate into Small samples of substances (liquid) Chromatography separates the components of a mixture based on how attracted the individual components are to the chromatography paper vs. the liquid

Gas Chromatography Relies on the fact that different compounds dissolve to different extents in a particular liquid Also can be used to separate based on size

Gas Chromatography

Column Chromatography Separates the components of a mixture based on the differences in size The smallest molecules exit the column first The largest molecules exit the column last Separation can also be based on polarity (attraction) to the material in the column

Other Techniques… Sifting magnetism

Separation Challenge Write a procedure for how you would separate a mixture of sand, salt, and iron into 3 separate containers Procedure must be DETAILED, use complete sentences. Indicate what materials you need! You will carry out this procedure next class