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Matter & Change A. Describing Matter Understanding matter begins with observation Matter is anything that has mass and takes up space Chemistry – the study of matter and the changes it undergoes B. Four States of Matter Solids particles vibrate but can’t move around fixed shape fixed volume Virtually incompressible B. Four States of Matter Liquids particles can move around but are still close together variable shape fixed volume Virtually incompressible B. 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 B. Four States of Matter Plasma particles collide with enough energy to break into charged particles (+/-) gas-like, variable shape & volume stars, fluorescent light bulbs, TV tubes II. Properties & Changes in Matter Extensive vs. Intensive Physical vs. Chemical A. Physical Properties Physical Property can be observed without changing the identity of the substance B. 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: scent) C. Extensive vs. Intensive Examples: boiling point intensive volume extensive mass extensive density intensive conductivity intensive D. Physical Changes Physical Change changes the form of a substance without changing its identity properties remain the same Examples: cutting a sheet of paper, breaking a crystal, all phase changes D. Phase Changes – Physical Evaporation = Liquid -> Gas Condensation = Gas -> Liquid Melting = Solid -> Liquid Freezing = Liquid -> Solid Sublimation = Solid -> Gas Deposition = Gas -> Solid E. Chemical Properties Chemical Property describes the ability of a substance to undergo changes in identity F. Physical vs. Chemical Properties Examples: melting point physical flammable chemical density physical magnetic physical tarnishes in air chemical G. 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 from original substances G. Chemical Changes Signs of a Chemical Change change in color or odor formation of a gas formation of a precipitate (solid) change in light or heat H. Physical vs. Chemical Changes Examples: rusting iron chemical dissolving in water physical burning a log chemical melting ice physical grinding spices physical What Type of Change? What Type of Change? III. Classification of Matter Matter Flowchart Pure Substances Mixtures A. Matter Flowchart MATTER yes Can it be physically separated? MIXTURE yes Is the composition uniform? Homogeneous Mixture (solution) no PURE SUBSTANCE no Heterogeneous Mixture yes Can it be chemically decomposed? Compound no Element A. Matter Flowchart Examples: graphite element pepper hetero. mixture sugar (sucrose) compound paint hetero. mixture soda solution B. Pure Substances Element composed of identical atoms EX: copper wire, aluminum foil B. Pure Substances Compound composed of 2 or more elements in a fixed ratio properties differ from those of individual elements EX: table salt (NaCl) C. Mixtures Variable combination of 2 or more pure substances. Heterogeneous Homogeneous C. Mixtures Solution homogeneous very small particles particles don’t settle EX: rubbing alcohol C. Mixtures Heterogeneous medium-sized to large-sized particles particles may or may not settle EX: milk, freshsqueezed lemonade C. Mixtures Examples: Answers: tea Solution muddy water Heterogeneous fog Heterogeneous saltwater Solution Italian salad dressing Heterogeneous III. Density Fun Formula Simple Calculations Dimensional Analysis A. Derived Units Combination of base units Volume – length length length 1 cm3 = 1 mL 1 dm3 = 1 L Density – mass per unit volume (g/cm3) M D= V Broken Heart M D V Density Density is a physical property of matter, as each element and compound has a unique density associated with it. The density of any sample of a substance at the same temperature will always be the same. Density If a substance is more dense than a liquid it will sink in it, if it is less dense than it will float The density of water is 1.00 g/mL, however this varies slightly with temperature B. Density Calculations An object has a volume of 825 cm3 and a density of 13.6 g/cm3. Find its mass. GIVEN: WORK: V = 825 cm3 D = 13.6 g/cm3 M=? M = DV M D V M = (13.6 g/cm3)(825cm3) M = 11,220 g M = 11,200 g B. Density Calculations A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid? GIVEN: WORK: D = 0.87 g/mL V=? M = 25 g V=M D M D V V= 25 g 0.87 g/mL V = 28.7 mL = 29 mL B. Density Calculations You have a sample with a mass of 620 g and a volume of 753 cm3. Find its density. GIVEN: WORK: M = 620 g V = 753 cm3 D=? D=M V M D V D= 620 g 753 cm3 D = 0.82 g/cm3 C. Density Calculations with DA Used when units do not agree Conversions must be made before using formula M D= V g D= 3 cm C. Density Calculations with DA You have 3.10 pounds of gold. Find its volume in cm3 if the density of gold is 19.3 g/cm3. cm3 lb 3.10 lb 1 kg 1000 g 1 cm3 2.2 lb 1 kg 19.3 g = 73.0 cm3 C. Density Calculations with DA You have 0.500 L of water. Find its mass in ounces if the density of water is 1.00 g/cm3. L oz 0.500 L 1000 mL 1 cm3 1.00g 1 kg 2.2 lbs 16 oz 1L 1 mL 1 cm3 1000 g 1kg 1lb = 17.6 oz I threw a plastic ball in the pool for my dog to fetch. The mass of the ball was 125 grams. What must the volume be to have a density of 0.500 g/mL. ( I want it to float of course!) A little aluminum boat (mass of 14.50 g) has a volume of 450.00 cm3. The boat is place in a small pool of water and carefully filled with pennies. If each penny has a mass of 2.50 g, how many pennies can be added to the boat before it sinks? I. 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+BC In an experiment 12.36 g of powdered aluminum is reacted with 23.65 g of iron oxide. If 16.8 g of iron are produced, what is the mass of the aluminum oxide produced?