Matter & Its Properties

1. Matter & Its Properties Ch 1: Lesson 3 Honors Chemistry K. Davis

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

3. Substances • Atoms: the building blocks of all matter • Ions: atoms that become negatively or positively charged • Element: matter containing only one type of atom; ex. hydrogen and oxygen

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

5. Four States of Matter • Liquids • particles can move around but are still close together • variable shape • fixed volume • Virtually incompressible

6. 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

7. Four States of Matter • Plasma • particles collide with enough energy to break into charged particles (+/-) • gas-like, variableshape & volume • stars, fluorescentlight bulbs, TV tubes

8. Four States of Matter

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

10. 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)

11. Intensive Physical Properties • The intensive physical properties for a sample of a pure substance remain constant. • ex. pure water- always a colorless liquid that boils at 100ºC at sea level; doesn’t matter if you have 10 mL or 1 L • Melting and boiling point are examples of these constant physical properties. • can be used to help identify a substance

12. Extensive vs. Intensive • Examples: • boiling point • volume • mass • density • conductivity intensive extensive extensive intensive intensive

13. Density – a physical property Derived units = Combination of base units Volume (m3 or cm3 or mL) length  length  length Or measured using a graduated cylinder M V D = 1 cm3 = 1 mL 1 dm3 = 1 L • Density (kg/m3 or g/cm3 or g/mL) • mass per volume

14. Density Mass (g) Volume (cm3)

15. Density An object has a volume of 825 cm3 and a density of 13.6 g/cm3. Find its mass. GIVEN: V = 825 cm3 D = 13.6 g/cm3 M = ? WORK: M = DV M = (13.6 g/cm3)(825cm3) M = 11,220 g M = 11,200 g

16. Density A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid? WORK: V = M D V = 25 g 0.87 g/mL GIVEN: D = 0.87 g/mL V = ? M = 25 g = 28.736 mL V = 29 mL

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

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

19. Physical Changes • Physical Change • changes the form of a substance without changing its identity • properties remain the same • Ex: cutting a sheet of paper, breaking a crystal, all phase changes

20. Some Physical Changes • Boiling • Condensation • Dissolving • Evaporation • Freezing • Melting • Sublimation

21. Evaporation = Condensation = Melting = Freezing = Sublimation = Liquid -> Gas Gas -> Liquid Solid -> Liquid Liquid -> Solid Solid -> Gas Phase Changes – Physical

22. 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

23. 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

24. Change of Energy • All physical & chemical changes involve a change of energy. • Endothermic – energy absorbed • a positive number (+) means endothermic • feel cold to the touch • Exothermic – energy released • a negative number (-) means exothermic • feel warm or hot to the touch

25. Some Chemical Changes • Combustion • Corrosion • Electrolysis • Fermentation • Metabolism • Photosynthesis • Bubble formation • Temperature change • Smell • Rust

26. Tip for Distinguishing • Is the change permanent? Can I get the original substance back after the change?” • If so, it is a physical change. • If not, it is a chemical change.

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

28. What Type of Change?    

29. What Type of Change?

30. 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

31. Conservation of Mass • 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

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

33. Matter Flowchart • Examples: • graphite • pepper • sugar (sucrose) • paint • soda element hetero. mixture compound hetero. mixture solution

34. Pure Substances • Element • composed of identical atoms • EX: copper wire, aluminum foil

35. Pure Substances • Compound- ex. table salt (NaCl) • composed of 2 or more elements in a fixed ratio • properties differ from those of individual elements • Molecule • smallest particle of a compound

36. Mixtures • Variable combination of 2 or more pure substances that is physically combined. • There is no particular ratio and each part of the mixture keeps its own properties. • Ex. Perfume, potting soil, salad dressings, and tea. Heterogeneous Homogeneous

37. Mixtures • Solution • Homogeneous mixture • very small particles • substances are in the same amount in all parts of the mixture • particles don’t settle • ex. rubbing alcohol, perfume

38. Mixtures • Heterogeneous • medium-sized to large-sized particles • substances in the mixture are not evenly mixed • particles may or may not settle • ex. milk, fresh-squeezed lemonade, salad dressing, potting soil

39. Heterogeneous Mixtures • Colloid: a heterogeneous mixture with larger particles that never settle; scatter light in the Tyndall effect. • Ex. Milk • Suspension: a heterogeneous mixture containing a liquid in which visible particles settle

40. Examples: tea muddy water fog saltwater Italian salad dressing Answers: Solution Heterogeneous Heterogeneous Solution Heterogeneous Mixtures

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

42. 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

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

44. Crystallization • Separation technique resulting 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 • Ex. Rocky candy

45. 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