Matter

a substance changes some physical property… During a “__________ change” a substance changes some physical property… http://216.70.123.96/images/uploads/iceberg.jpg PHOTO of iceberg H2O

…but it is still the same material with the same ____________ composition. gas H2O solid liquid

______________ Property: The tendency of a substance to change into another substance. Photo: http://images.google.com/imgres?imgurl=http://lh3.google.com/_aY_0d2zXNW4/RXHxKerci-I/AAAAAAAAAAg/gSRVWgC4BKk/s800/_DSC0167.jpg&imgrefurl=http://picasaweb.google.com/lh/photo/HW7I5kPuUN2Mo57PJPG9RA&h=529&w=800&sz=96&hl=en&start=3&um=1&tbnid=JY9_ZpLYaeOgwM:&tbnh=95&tbnw=143&prev=/images%3Fq%3Dsteel%2Brusting%26um%3D1%26hl%3Den%26rlz%3D1T4RNWK_enUS255US257 Steel rusting: caused by iron (Fe) reacting with oxygen (O2) to produce rust (Fe2O3) 4 Fe + 3 O2 2 Fe2O3

_____________ Change: Any change involving a rearrangement of ________. http://www.pdsm.wpafb.af.mil/toprac/atoms_full_std.gif

Chemical ____________: The process of a chemical change...

During a “chemical reaction” new materials are formed by a change in the way atoms are ____________ together.

Physical and Chemical Properties Examples of Physical Properties Boiling point Color Slipperiness Electrical conductivity Melting point Taste Odor Dissolves in water Shininess (luster) Softness Ductility Viscosity (resistance to flow) Volatility Hardness Malleability Density (mass / volume ratio) Examples of Chemical Properties Burns in air Reacts with certain acids Decomposes when heated Explodes Reacts with certain metals Reacts with certain nonmetals Tarnishes Reacts with water Is toxic Chemical properties can ONLY be observed during a chemical reaction! Ralph A. Burns, Fundamentals of Chemistry 1999, page 23

Physical & Chemical Changes CO2 crushing heating Pyrex _______________ _____________ CaO Limestone, CaCO3 Crushed limestone, CaCO3 The crushing of limestone is a physical change; it does not alter the chemical composition of the limestone. The heating of limestone is a chemical change; the limestone decomposes into two other substances, lime and carbon dioxide. http://www.fi.edu/fellows/payton/rocks/expert/graphics/LIMESTON.JPG http://www.greenleafsupply.com/images/Dolomiteb.jpg Lime and carbon dioxide, CaO + CO2

Light hastens the decomposition of hydrogen peroxide, H2O2. Sunlight energy O2 Pyrex Pyrex H2O2 H2O Light hastens the decomposition of hydrogen peroxide, H2O2. The dark bottle in which hydrogen peroxide is usually stored keeps out the light, thus protecting the H2O2 from decomposition.

Solid, Liquid, Gas (a) Particles in _____ (b) Particles in _______ (c) Particles in ______

_________ H2O(s) Ice Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 31

Ice H2O(s) Ice Photograph of ice model Photograph of snowflakes Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

_________ In a ________ H2O(l) Water molecules are in constant ________ molecules are close together Liquids are almost incompressible Liquids do not fill the container some writing from Kotz (PowerPoint online) H2O(l) Water Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 31

_________ H2O(g) Steam Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 31

____ ________ ______ Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 441

States of Matter _____ ________ ________ Holds Shape Fixed Volume Solid In a solid the molecules are closely bound to one another by molecular forces. A solid holds its shape and the volume of a solid is fixed by the shape of the solid. Liquid In a liquid the molecular forces are weaker than in a solid. A liquid will take the shape of its container with a free surface in a gravitational field. In microgravity, a liquid forms a ball inside a free surface. Regardless of gravity, a liquid has a fixed volume. Gas In a gas the molecular forces are very weak. A gas fills its container, taking both the shape and the volume of the container _____ ________ ________ heat heat Holds Shape Fixed Volume Shape of Container Free Surface Fixed Volume Shape of Container Volume of Container

MATTER yes no _________ _________ yes no yes no _________ Mixture Can it be physically separated? _________ _________ yes Is the composition uniform? no yes Can it be chemically decomposed? no _________ Mixture (solution) _____________ Mixture _________ __________ Colloids Suspensions Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

Matter Flowchart Examples: graphite pepper element sugar (sucrose) paint soda element hetero. mixture compound hetero. mixture Graphite image: geology.about.com/.../bl/images/blgraphite.htm solution homo. mixture Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

Pure Substances ______________ composed of identical __________ EX: copper wire, aluminum foil http://www.friedlandindustries.com/images/new/NonferrousMetalsCopper.jpg Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

Pure Substances ______________ composed of 2 or more __________ in a fixed ratio properties differ from those of individual elements EX: table salt (NaCl) Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

______________ Variable combination of two or more pure substances. ________________ ________________ Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

Methods of ____________ Mixtures Magnet Filter Decant Evaporation Centrifuge Chromatography Distillation

_________ separates a liquid from a solid Mixture of solid and liquid Stirring rod Filtrate (liquid component of the mixture) Filter paper traps solid Funnel _________ separates a liquid from a solid Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 40

___________________ Tie-dye t-shirt Black pen ink DNA testing Tomb of Unknown Soldiers Crime scene Paternity testing

Paper Chromatography http://www.moe.gov.sg/edumall/tl/digital_resources/chemistry/images/paper_chromatography.jpg

A _____________ Apparatus liquid with a solid dissolved in it thermometer condenser tube distilling flask pure liquid receiving hose connected to cold water faucet “A Distillation Apparatus”   Description: This transparency shows an apparatus used for laboratory distillations. Basic Concepts The separation of substances by distillation occurs because the boiling point of the substances differ. The substance with the lowest boiling point boils away first. Distillation is based on the principle that a substance will change from a liquid to a vapor during heating and from a vapor back to a liquid while cooling. Teaching Strategies Use this slide to explain to students how a distillation apparatus is used to purify liquids and to separate the components of liquid mixtures. Begin by reviewing the phases of matter, stressing the processes of evaporation and condensation. Remind students that different liquids have different boiling points. Point out that substances that are solids at room temperature usually have higher boiling points than do substances that are liquids at room temperature. Questions If the distilling flask shown in the diagram were open to the air (rather than being connected to the condensor), what would happen to each component of the mixture in the flask as boiling continued? Explain your answer to question 1 in terms of the boiling points of the liquid and the dissolved solid. In the distillation apparatus, the vaporized liquid must enter the condenser. The condenser consists of a long tube within another tube (the jacket). The substance in the central tube and the jacket cannot mix. Cold water enters at the bottom of the jacket and exits at the top. What is the function of the condenser jacket? How would changing the length of the condenser jacket affect how well it performs this function? Explain why the liquid entering the receiving flask is pure. To separate a mixture of methanol and water, you set up a distillation apparatus and heat the mixture to the boiling point of methanol, 65 oC. What substance would you expect to collect at the receiving flask? When you finish the experiment, you discover that the substance in the receiving flask is not pure. It still contains both water and methanol. Can you explain why? (Hint: Think about vapor pressures.) Before automobiles were invented, crude petroleum was used mainly as a source of kerosene. The petroleum was heated in a device called a still. Gasoline, then considered to be useless, evaporated first into the air. Kerosene boiled off next and was condensed and collected. A tar-like residue remained in the still. From this information, what can you deduce about the boiling points of gasoline, kerosene, and the residue? How will you know when all of one component has been separated? Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 282

Separation of a sand-saltwater mixture. Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 40