Matter: Properties & Change Chapter 3

Matter Matter – anything that has mass and takes up space Everything around us Chemistry – the study of matter and the changes it undergoes

Four States of Matter Solids particles vibrate but can’t move around fixed shape fixed volume incompressible

Four States of Matter Liquids particles can move around but are still close together variable shape (shape of container) fixed volume virtually incompressible

Four States of Matter Gases particles can separate and move throughout container variable shape variable volume easily compressed vapor = gaseous state of a substance that is a liquid or solid at room temperature

Four States of Matter Plasma particles collide with enough energy to break into charged particles (+/-) gas-like, variable shape & volume stars, fluorescent light bulbs

Physical Properties Physical Property can be observed without changing the identity of the substance

Physical Properties Physical properties can be described as one of 2 types: Extensive Property depends on the amount of matter present (example: length) Intensive Property depends on the identity of substance, not the amount (example: density)

Chemical Properties Chemical Property describes the ability of a substance to undergo changes in identity

Physical vs. Chemical Properties Examples: melting point flammable density magnetic tarnishes in air physical chemical

Physical Changes Physical Change changes the form of a substance without changing its identity properties remain the same Examples: cutting a sheet of paper, all phase changes

Phase Changes Evaporation = Condensation = Melting = Freezing = Sublimation = Deposition = Liquid  Gas Gas  Liquid Solid  Liquid Liquid  Solid Solid  Gas Gas  Solid

Chemical Changes Process that involves one or more substances changing into a new substance Commonly referred to as a chemical reaction New substances have different compositions and properties than the original substances

Chemical Changes Signs of a Chemical Change change in color or odor formation of a gas formation of a precipitate (solid) change in temperature

Physical vs. Chemical Changes Examples: rusting iron dissolving in water burning a log melting ice grinding spices chemical physical

Law of Conservation of Mass Although chemical changes occur, mass is neither created nor destroyed in a chemical reaction Mass of reactants equals mass of products massreactants = massproducts A + B C

Conservation of Mass GIVEN: WORK: 10.00 g = 9.86 g + moxygen In an experiment, 10.00 g of red mercury (II) oxide powder is placed in an open flask and heated until it is converted to liquid mercury and oxygen gas. The liquid mercury has a mass of 9.26 g. What is the mass of the oxygen formed in the reaction? GIVEN: Mercury (II) oxide  mercury + oxygen mmercury(II) oxide = 10.00 g mmercury = 9.86 g moxygen = ? WORK: 10.00 g = 9.86 g + moxygen moxygen = (10.00 g – 9.86 g) moxygen = 0.74 g Mercury (II) oxide  mercury + oxygen Mmercury(II) oxide = 10.00 g Mmercury = 9.26 Moxygen = ? massreactants = massproducts

Can it be physically separated? Matter Flowchart MATTER yes no Can it be physically separated? MIXTURE PURE SUBSTANCE Is the composition uniform? no yes Can it be chemically decomposed? no yes Homogeneous Mixture (solution) Heterogeneous Mixture Compound Element

Matter Flowchart Examples: graphite element pepper sugar (sucrose) paint soda element heterogeneous mixture compound solution

Pure Substances Element composed of identical atoms Example: copper wire, aluminum foil

Pure Substances Compound composed of 2 or more elements in a fixed ratio properties differ from those of individual elements Example: table salt (NaCl)

Mixtures Variable combination of 2 or more pure substances. Heterogeneous Homogeneous

Mixtures Solution homogeneous very small particles particles don’t settle Example: rubbing alcohol

Mixtures Heterogeneous medium-sized to large-sized particles particles may or may not settle Example: milk, fresh-squeezed lemonade

Mixtures Examples: Answers: tea muddy water fog NaCl & H2O Italian salad dressing Answers: Solution Heterogeneous

Separating Mixtures Substances in a mixture are physically combined, so processes bases on differences in physical properties are used to separate components Numerous techniques have been developed to separate mixtures to study components Filtration Distillation Sublimation Crystallization Chromatography

Filtration Used to separate heterogeneous mixtures composed of solids and liquids Uses a porous barrier to separate the solid from the liquid Liquid passes through leaving the solid in the filter paper

Distillation Used to separate homogeneous mixtures Based on differences in boiling points of substances involved

Sublimation Process during which a solid changes to a vapor without melting Can be used to separate two solids present in a mixture when one of the solids sublimates but the other does not

Crystallization Separation technique that results in the formation of pure solid particles from a solution containing the dissolved substance As one substance evaporates, the dissolved substance comes out of solution and collects as crystals Produces highly pure solids Rocky candy is an example of this

Chromatography Separates components of a mixture based on ability of each component to be drawn across the surface of another material Mixture is usually liquid and is usually drawn across chromatography paper Separation occurs because various components travel at different rates Components with strongest attraction for paper travel the slowest; components with strongest attraction for the liquid travel the fastest

Separation of a Compound The Electrolysis of Water Compounds must be separated by chemical means. With the application of electricity, water can be separated into its elements Reactant  Products Water  Hydrogen + Oxygen 2 H2O  2 H2 + O2