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Matter & Energy

Matter & Energy. Introduction Another View. Classifying Matter According to its State: Solid, Liquid, Gas. Water can exist as a solid, liquid or gas. Classifying Matter According to its State: Kinetic Theory. Compressibility. Solids are incompressible Gases are compressible

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Matter & Energy

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  1. Matter & Energy Introduction Another View

  2. Classifying Matter According to its State:Solid, Liquid, Gas • Water can exist as a solid, liquid or gas

  3. Classifying Matter According to its State:Kinetic Theory

  4. Compressibility • Solids are incompressible • Gases are compressible • Liquids are very slightly compressible – usually considered incompressible

  5. Crystalline Solids Long-range order Repeating patterns Amorphous Solids No long range order Polymers, glass Types of Solid Matter - Sodium Chloride

  6. Which of the following does not describe the gaseous state? a. Same shape as a closed container b. Same volume as a closed container c. Random, independent particle movement d. Easily compressed e. All describe the gaseous state

  7. Which of the following does not describe the liquid state? a. Particles vibrate in fixed position b. Same shape as the bottom of the container c. Constant volume d. Can be poured e. All describe the liquid state

  8. Which of the following does not describe the solid state? a. Rigid, fixed, constant shape b. Constant volume c. Easily compressed d. Particles vibrate in fixed position e. All describe the solid state

  9. Physical Change C3H8 (l)  C3H8 (g) Chemical Change C3H8(l) + O2(g) CO2(g) + H2O(l)

  10. How do chemists describe/identify a substance? • Physical properties: • Appearance, hardness, odor • Density, viscosity, electrical conductivity, boiling point, melting point • Physical changes – change the physical form of matter without changing its chemical identity • Melting ice • Dissolving sugar in water • Name a physical property that changes during the melting of ice

  11. Phase (solid, liquid, gas) Mass Volume Density Melting Point Boiling Point Volatility Specific Heat Capacity Malleability Ductility Taste Odor Color Texture Shape Solubility Electrical Conductance Thermal Conductance Magnetism Some Physical Properties

  12. Melting: solid  liquid Boiling: liquid  gas Subliming: solid  gas Freezing: liquid  solid Condensing: gas  liquid Deposition: gas  solid Phase Changes – require heating or cooling the substance An example of sublimation- crystals of iodine changing to vapor I2(s)  I2(g)

  13. How do chemists describe/identify a substance? • Chemical changes – the chemical identity of a substance is destroyed and a new substance(s) is formed • Rusting of iron • The fading of a t-shirt with exposure to sunlight • Chemical properties: describe reactivity, i.e. Flammability

  14. Chemical Changes involve the rearrangement of the way atoms are bonded • Methane reacts with oxygen to produce water and carbon dioxide • Reactants: oxygen and methane • Products: water and carbon dioxide

  15. Acidity Corrosiveness Reactivity Inertness Flammability Oxidizing Ability Basicity (aka Alkalinity) Stability Explosiveness Combustibility Reducing Ability Some Chemical Properties

  16. Determining Whether a Change is Chemical or Physical • Both involve changes in physical appearance • Physical changes are reversible • Potassium chromate • Ammonium dichromate  ammonia + water + chromium (III) oxide

  17. Evidence of Chemical Changes • What do you notice? • Which observations could also be noticed during a physical change? None as the bubbles in (a) are escaping hydrogen gas

  18. Which of the following properties is/are classified as chemical?  • the taste of honey • the ability of hair to stretch • the corrosive character of hydrochloric acid • the combustibility of ethanol • the softness of talc

  19. Classify each of the following changes as physical or chemical • grape juice turns to wine • wood burns to ashes • a broken leg heals itself • grass grows • an infant gains 10 pounds • a rock is crushed to powder • baking soda fizzes in vinegar • vinegar and oil separate into two layers • helium balloon decreases in size

  20. Classifying Matter According to its Composition: Elements, Compounds, & Mixtures • Pure Substance – composed of one type of atom or molecule • Own set of physical and chemical properties • Mixtures – composed of two or more different types of atoms or molecules in variable proportions • Physical and chemical properties vary with the proportions of the components of the mixture

  21. Pure Substance • Own set of physical and chemical properties • Mixtures • Physical and chemical properties vary with the proportions of the components of the mixture

  22. Classify each of the following as a pure substance or mixture • gold • air • chunky peanut butter • sugar completely dissolved in water • ice

  23. Classifying Matter According to its Composition: Elements, Compounds, & Mixtures

  24. Classifying Matter According to its Composition: Elements • Elements can not be broken down into simpler substances, i.e. silver (Ag)

  25. Periodic Table

  26. Classifying Matter According to its Composition:Compounds • Compounds – substance composed of two or more elements in fixed proportions, i.e. H2O & CO2

  27. Classifying Matter According to its Composition: Elements, Compounds, & Mixtures

  28. Classifying Matter According to its Composition:Mixtures • Heterogeneous Mixtures – oil & water, sand & gravel, composition is not uniform. 2 separate samples would yield varying amounts of the components • Homogeneous– Sugar dissolved in water. Uniform composition. 2 separate samples would yield the same ratio of components

  29. A Microscopic View

  30. Pure Substance • Own set of physical and chemical properties • Mixtures • Physical and chemical properties vary with the proportions of the components of the mixture • We can take advantage of the different physical properties of a mixture to separate the components.

  31. Separation of Mixtures • Methods based on physical properties Filtration – based on size Distillation – based on boiling point

  32. Separation of Compounds • Methods based on chemical changes • 2H2O(l)  2H2(g) + O2(g) • Involve the rearrangement of the way atoms are bonded • New compounds or elements are formed Electrolysis of water

  33. When water boils, you can see bubbles rising to the surface of the water. Of what are these bubbles made? • air • hydrogen and oxygen gas • oxygen gas • water vapor • carbon dioxide gas

  34. Mixture Separation • How could I separate a mixture of sugar and sand?

  35. We have a mixture of sawdust (wood chips), copper, iron and salt • We want to three separate piles • ID Physical properties of components – • Separating different compounds:

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