Objectives - Matter Explain why mass is used as a measure of the quantity of matter. Describe the characteristics of elements, compounds, and mixtures.

Objectives - Matter Explain why mass is used as a measure of the quantity of matter. Describe the characteristics of elements, compounds, and mixtures. Solve density problems by applying an understanding of the concepts of density. Distinguish between physical and chemical properties and physical and chemical changes. Demonstrate an understanding of the law of conservation of mass by applying it to a chemical reaction.

Classifying Matter

MATTER yes no MIXTURE PURE SUBSTANCE yes no yes no Homogeneous Mixture
Can it be physically separated? MIXTURE PURE SUBSTANCE yes Is the composition uniform? no yes Can it be chemically decomposed? no Homogeneous Mixture (solution) Heterogeneous Mixture Compound Element Colloids Suspensions Courtesy Christy Johannesson

How Do We Classify Matter?
All matter can be classified as either a pure substance or a mixture. Example: Gold vs Gold Alloy 24 karat karat, 18/24 gold Pure substance mixture

Gold 24 karat gold 18 karat gold 14 karat gold 24/24 atoms Au
Copper Silver 24 karat gold karat gold karat gold Pure gold (24 karat) is too soft (malleable) for use in jewelry. An alloy is made with copper or silver to make the gold harder and more durable. 14 karat gold means if you take 24 atoms out of the sample 14 will be gold atoms and the remaining 10 atoms another metal. Many years ago, coins were made from pure silver and pure gold. Dishonest people would shave off the edges of the coins to steal a small amount of silver or gold. Ridges were added to coins to stop people from shaving the coins. Emphasize that alloys are solutions or mixtures of metals. An alloy’s characteristics differ from those of the metals that compose it. How are the silver atoms arranged in the14-karat gold? (They are evenly dispersed among the gold atoms.) If you were to melt the ring, how would the silver atoms be arranged in the solution? (They would be evenly dispersed.) Can an alloy be composed of more than two different metals? (yes) 24/24 atoms Au 18/24 atoms Au 14/24 atoms Au

Matter Can be divided into Pure Substances & Mixtures

Pure Substances (or just substances)
Type of matter for which all samples have the same properties; they behave exactly the same way Two types: Element or a Compound

Element Samples of a substance that contain only one type of atom
An element CAN’T be broken down into simpler substances by chemical or physical means Represent with Chemical Symbol Ex: Aluminum (Al) & Copper (Cu)

Elements Elements consist of… Single atoms, or
Groups of atoms of the same type (molecules) The diatomic molecules “Start at seven and make a seven…Hydrogen is the number sign”

Diatomic Elements, 1 and 7 H2 N2 O2 F2 Cl2 Br2 I2

Top Ten Elements in the Universe
Percent Element (by atoms) Hydrogen 73.9 Helium 24.0 Oxygen Carbon Neon Iron Nitrogen Silicon Magnesium Sulfur A typical spiral galaxy (Milky Way is a spiral galaxy) Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 26

The Composition of Air Air Nitrogen Helium Oxygen Neon Water vapor
Carbon dioxide Argon Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 34

Chart Examining Some Components of Air
Nitrogen consists of molecules consisting of two atoms of nitrogen: Oxygen consists of molecules consisting of two atoms of oxygen: Water consists of molecules consisting of two hydrogen atoms and one oxygen atom: Argon consists of individual argon atoms: Carbon dioxide consists of molecules consisting of two oxygen atoms and one carbon atom: Neon consists of individual neon atoms: Helium consists of individual helium atoms: N2 O2 H2O Ar CO2 Ne He Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 35

Uses of Some Elements Aluminum- can be used as a blanket because it reflects radiation (a form of heat) Americium- used in smoke detectors- radioactive Tungsten- very high melting point- used in lightbulb filaments Titanium- very lightweight and strong metal- used in frames for airplanes and in engines Lead- high density- makes it a good barrier for radiation- blocks particle movement

Compounds Substance made up of 2 or more different elements that are chemically combined Millions of different types…why? Represent by chemical formula Cpd can be broken down by chemical means Electrolysis of Water 2 H2O  2 H2 + O2 Cannot be separated by physical means

Properties of Compounds
Every sample of a particular compound has the same properties as every other sample Ex: every sample of pure water (H2O) smells, tastes, looks, and reacts the same

Classifying Matter: Element or Compound?
Element - Atom S8 ? Element- Molecule H2O ? Compound Cl2 ? H2O2 ?

Mixture A combo of 2 or more substances- each retain its individual properties No chemical bonds b/t the diff. substances can be separated by physical means

Suspension Colloid Solution

Homogenous Mixture All regions of mixture are identical in composition and properties Evenly mixed or uniformly distributed at the particle level  called solutions Ex: soda, salt water, Kool-Aid Alloy – solid homogeneous mixture

Solution Homogeneous mixtures containing particles so small they cannot be seen with a microscope and will never settle to the bottom of the container (Dissolves) tap water, salt water, food coloring and water, colas, vinegar

Mixtures Solution homogeneous very small particles no Tyndall effect
particles don’t settle EX: rubbing alcohol Courtesy Christy Johannesson

An alloy is a mixture of metals.
Brass = Copper + Zinc Solid brass homogeneous mixture a substitutional alloy Solid Brass Consumer Tip Pay attention to labels when purchasing brass. Brass is sold with the label ‘Brass’ or ‘Solid Brass’. ‘Brass’ means brass coated – the object is not ‘solid brass’. It is likely inexpensive, cheap zinc in the center and has only a thin coating of brass on the outside. Toilet bowl seat screws are often sold as ‘brass’ ($1.29) or ‘solid brass’ ($1.99). Pay more, the ‘brass’ screw may snap off as zinc is a brittle metal under stress. ‘Solid brass’ is stronger and the better value. Copper Zinc

Brass Plated Brass = Copper + Zinc Brass plated heterogeneous mixture
Only brass on outside Brass Plated Copper Zinc

Hardened Steel Steel Iron Carbon a interstitial alloy
Carbon is added to steel to make it harder. The addition of too much carbon makes steel very strong, but brittle. A bridge made this way would not sag when stressed, but would snap when too much pressure was applied. Engineers figure the optimal amount of carbon to add to make steel strong, but not too brittle. Look for link: Steel Steel Iron Carbon

Steel Alloys Stainless steel Tungsten hardened steel Vanadium steel
Tensile strength Force is added Stainless steel Tungsten hardened steel Vanadium steel We can engineer properties Add carbon to increase strength Too much carbon  too brittle and snaps Too little carbon  too ductile and iron bends Look for links:

Galvanized Nails and Screws
Zinc coating prevents rust Use deck screws for any outdoor project Iron will rust if untreated Weaken and break Galvanized means to be coated with zinc. The Tin Man – Wizard Of Oz (1939)

Nitinol Wire Alloy of nickel and titanium Remembers shape when heated
Applications: surgery, shirts that do not need to be ironed. Link to show video of nitonel wire performing. Add reference to ChemMatters article on nitonel wire Nitinol (pronounced “night-in-all”) is a generic trade name for NiTi alloys, which stands for Nickel (Ni), Titanium (Ti) and the US Naval Ordinance Laboratory (NOL) where the alloy was discovered in the early 1960s by William Beuhler. Nitinol's physical function resembles Biological Muscle: when activated it contracts - an effect opposite to that of standard metals that expand when heated. To activate Nitinol it is heated above its transition temperature (typically 70°C). When the material cools it can be stretched back it its original shape. But it also has a Shape Memory Effect (SME): It can be made to remember a particular shape. Once the memory is established, it can be bent out of shape. Heating the alloy above its transition temperature will return it to its memorized shape. You can modify the "memory" shape of the wire supplied by annealing the wire.

Heterogeneous Mixture
Made of materials that can be distinguished from each other Not uniform in composition

Mixtures Variable combination of two or more pure substances.
Heterogeneous Homogeneous Courtesy Christy Johannesson

Heterogeneous Mixtures
Colloid heterogeneous medium-sized particles Tyndall effect particles don’t settle EX: milk, fog, smoke Courtesy Christy Johannesson

Colloid vs. Solution – how to test for a colloid
Pass a beam of light through the mixture If the beam is invisible- it is a solution If the beam is visible- it is a colloid The visible beam through the colloid is called the Tyndall effect

Tyndall Effect

Heterogeneous Mixtures
Suspension heterogeneous large particles Tyndall effect particles settle EX: fresh-squeezed lemonade Courtesy Christy Johannesson

Mixtures Examples: colloid suspension colloid solution suspension
mayonnaise muddy water fog saltwater Italian salad dressing colloid suspension colloid solution suspension Courtesy Christy Johannesson

Suspension Heterogeneous mixture containing a liquid in which visible particles settle out over time like dirty water

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

Classification of Matter
heterogeneous mixture no uniform properties? no solution fixed composition? no element chemically decomposable? yes compound

Elements, Compounds, and Mixtures
oxygen atoms hydrogen atoms hydrogen atoms “Elements, Compounds, and Mixtures” Description: This slide shows the molecular composition of an element, a compound, and two mixtures. Basic Concepts All samples of a substance have the same molecular composition and intensive properties and are homogeneous. Elements and compounds are substances; mixtures are not. The elements making up a compound combine in fixed ratios. Mixtures can be separated by physical methods. Mixtures that have a uniform composition throughout are homogeneous; those that have parts with different compositions are heterogeneous. Teaching Suggestions Use this transparency to help students visualize the molecular composition of elements, compounds, and mixtures and to review the definitions of these terms. Make sure students understand the difference between the terms matter and substance. Remind students that elements and compounds are always homogeneous, while mixtures can be either homogeneous or heterogeneous. Questions: Which of the bottles pictured above contain(s) matter? Which contain(s) a single substance? Explain your answers. How many elements are present in each molecule of water shown in bottle (b)? What is the relative number of atoms of each element in a water molecule? As you know, ice is frozen water. In other words, ice and water are the same substance, in different phases. What would you expect the ratio of hydrogen atoms to oxygen atoms to be in a molecule of ice? Explain your reasoning. Bottle (c) and bottle (d) both contain mixtures. How are these mixtures similar? How are they different? Suppose you find an unlabeled bottle containing a clear liquid. Can you tell by looking at it whether the material is a compound or a mixture? Explain your answer. How can you prove that a sample of sea water is a mixture? Classify the following items as elements, compounds or mixtures; rice pudding, copper, carbon dioxide, air, milk, magnesium chloride, granite, mercury, and maple syrup. A chocolate-chip cookie with more chips in one part of the cookie than another can be used to demonstrate a heterogeneous mixture. Name two other materials that can be classified as heterogeneous mixtures. Explain your reasoning. (a) an element (hydrogen) (b) a compound (water) (c) a mixture (hydrogen and oxygen) (d) a mixture (hydrogen and oxygen) Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 68

Mixture - Solution Pure Substance - Compound

Mixture vs. Compound Different Alike Different Topic Topic Mixture
Involve substances Variable Composition Fixed Composition Topic Topic No bonds between components Contain two or more elements Bonds between components Mixture Compound Compounds have different properties than the elements they are made from. In a mixture, the mixture retains the properties of the materials it is made from. A chemical formula can always be written for a compound. Can be separated by physical means Can be separated into elements Can ONLY be separated by chemical means

Compounds vs. Mixtures Compounds have properties that are uniquely different from the elements from which they are made. A formula can always be written for a compound e.g. NaCl  Na + Cl2 Mixtures retain their individual properties. e.g. Salt water is salty and wet

How can you tell the difference between Mixture and Compound?
Mixture can be separated physically and keep its properties Compound can only be separated chemically and does NOT keep its properties

Characteristics that Distinguish Pure Substances from Mixtures
A pure substance has only one set of properties, but a mixture retains the properties of each of its constituents. The composition of a pure substance is fixed, but the composition of a mixture can vary widely.

Classification of Matter
(gas. Liquid, solid, plasma) Separated by PURE SUBSTANCES MIXTURES physical means into Separated by COMPOUNDS ELEMENTS HOMOGENEOUS MIXTURES HETEROGENEOUS MIXTURE chemical means into Kotz & Treichel, Chemistry & Chemical Reactivity, 3rd Edition , 1996, page 31

“Word Web” Summery Objective: To create a Word Web of the concepts related to Classifying “Matter” Web Should show how concepts &/or examples link correctly to Matter & to each other Each person has different Colored Pencil – Write your name on back of group paper with your color When its your turn, Make 1 addition or 1 correction to the group’s Word Web Then Pass to next person in group (Clockwise)

Reviewing Concepts Classifying Matter
Why does every sample of a given substance have the same properties? Explain why the composition of an element is fixed. Describe the composition of a compound. Why can the properties of a mixture vary? On what basis can mixtures be classified as solutions, suspensions, or colloids? Prentice Hall Physical Science Concepts in Action (Wysession, Frank, Yancopoulos) 2004 pg 44 Every sample of a given substance has the same properties because a substance has a fixed, uniform composition. An element has a fixed composition because it contains only one type of atom. A compound always contains two or more elements joined in a fixed proportion. The properties of a mixture can vary because the composition of a mixture is not fixed. Based on the size of its largest particles, a mixture can be classified as a solution, a suspension, or a colloid.

Methods of Separating Mixtures
Magnet Filter Decant Evaporation Centrifuge Chromatography Distillation

Applications Centrifuge Method Property Involved Magnet Filter Decant
Magnetism Recycling Filter Particle size Water treatment plant Decant Particle size; density Alcohol production Evaporation Liquid evaporates, but solid stays behind Salt production Distillation Liquid boiled off, removed, and re-condensed Purifying seawater 9Saudi Arabia) Chromatography Diff. Materials in mixture have diff. Attraction to chrom. media Nutrition studies, forensic analysis Centrifuge More dense materials go to the bottom Red blood cells from blood plasma

Separation of Mixtures
We CAN separate mixtures b/c constituents of the mixture have different properties NOTE: None of the methods for separating mixtures involve chemical reactions – we separate them PHYSICALLY!!!

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

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

Paper Chromatography

Paper Chromatography of Water-Soluble Dyes
orange red yellow Filter paper (stationary phase) Suggested red dye is not homogeneous Orange mixture of red and yellow Initial spots of dyes Direction of Water (mobile phase) movement

A Distillation 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

The solution is boiled and steam is driven off.
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 39

Salt remains after all water is boiled off.

No chemical change occurs when salt water is distilled.
Saltwater solution (homogeneous mixture) Distillation (physical method) Salt Pure water Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 40

Setup to heat a solution
Ring stand Beaker Wire gauze Ring Bunsen burner Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 42

Separation of a sand-saltwater mixture.

Separation of Sand from Salt
Gently break up your salt-crusted sand with a plastic spoon. Follow this flowchart to make a complete separation. Salt- crusted sand. Weigh the mixture. Pour into heat-resistant container. Fill with water. Stir and let settle 1 minute. Dry sand. Calculate weight of salt. Weigh sand. Decant clear liquid. No How does this flow chart insure a complete separation? Wet sand. Evaporate to dryness. Repeat 3 times? Yes

Distillation Distillation is a process of boiling a liquid and condensing and collecting the vapor. The liquid collected is the distillate. The usual purpose of distillation is purification or separation of the components of a mixture. This is possible because the composition of the vapor is usually different from that of liquid mixture from which it is obtained. Gasoline, kerosene, fuel oil, and lubricating oil are produced from petroleum by distillation. Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

Centrifugation Spin sample very rapidly: denser materials go to bottom (outside) Separate blood into serum and plasma Serum (clear) Plasma (contains red blood cells ‘RBCs’) Check for anemia (lack of iron) AFTER Before Blood Serum RBC’s A B C

Water Molecules Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 8

The decomposition of two water molecules.
Diatomic Diatomic oxygen molecule hydrogen molecules + Electric current 2 H2O  O H2

Electrolysis H2O(l) O2 (g) + 2 H2 (g) “electro” = electricity
Water Hydrogen gas forms Oxygen Electrode Source of direct current “electro” = electricity “lysis” = to split *H1+ H2O(l) O2 (g) H2 (g) water oxygen hydrogen This demonstration needs to be done using DC current (to produce a 2:1 H:O ratio). Use of AC current will produce equal amounts of hydrogen and oxygen gas. *Must add acid catalyst to conduct electricity Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 32

Electrolysis of Water Half reaction at the cathode (reduction):
hydrogen gas cathode oxygen anode D.C. power source water Half reaction at the cathode (reduction): 4 H2O e -  2 H OH 1- Half reaction at the anode (oxidation): 2 H2O  O H e -

Reviewing Concepts Physical Properties
List seven examples of physical properties. Describe three uses of physical properties. Name two processes that are used to separate mixtures. When you describe a liquid as thick, are you saying that it has a high or low viscosity? Prentice Hall Physical Science Concepts in Action (Wysession, Frank, Yancopoulos) 2004 pg 51 Viscosity, conductivity, malleability, hardness, melting point, boiling point, and density are examples of physical properties. Physical properties are used to identify a material, to choose a material for a specific purpose, or to separate the substances in a mixture. Filtration and distillation are two common separation methods.

Reviewing Concepts Physical Properties
Explain why sharpening a pencil is an example of a physical change. What allows a mixture to be separated by distillation? Prentice Hall Physical Science Concepts in Action (Wysession, Frank, Yancopoulos) 2004 pg 51 Viscosity, conductivity, malleability, hardness, melting point, boiling point, and density are examples of physical properties. Physical properties are used to identify a material, to choose a material for a specific purpose, or to separate the substances in a mixture. Filtration and distillation are two common separation methods.

Reviewing Concepts Chemical Properties
Under what conditions can chemical properties be observed? List three common types of evidence for a chemical change. How do chemical changes differ from physical changes? Prentice Hall Physical Science Concepts in Action (Wysession, Frank, Yancopoulos) 2004 pg 51 Chemical properties can be observed only when the substance in a sample of matter are changing into different substances. Three common types of evidence for a chemical change are a change in color, the production of a gas, and the formation of a precipitate. When matter undergoes a chemical change, the composition of the matter changes. When matter undergoes a physical change, the composition of the matter remains the same.

Reviewing Concepts Chemical Properties
Explain why the rusting of an iron bar decreases the strength of the bar. A pat of butter melts and then burns in a hot frying pan. Which of these changes is physical and which is chemical? Prentice Hall Physical Science Concepts in Action (Wysession, Frank, Yancopoulos) 2004 pg 51 Chemical properties can be observed only when the substance in a sample of matter are changing into different substances. Three common types of evidence for a chemical change are a change in color, the production of a gas, and the formation of a precipitate. When matter undergoes a chemical change, the composition of the matter changes. When matter undergoes a physical change, the composition of the matter remains the same.

Objectives - Matter Explain why mass is used as a measure of the quantity of matter. Describe the characteristics of elements, compounds, and mixtures.

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Objectives - Matter Explain why mass is used as a measure of the quantity of matter. Describe the characteristics of elements, compounds, and mixtures.

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Presentation on theme: "Objectives - Matter Explain why mass is used as a measure of the quantity of matter. Describe the characteristics of elements, compounds, and mixtures."— Presentation transcript:

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