MATTER Matter is anything that has MASS & VOLUME. Mass = the amount of matter an object contains Measured in grams (g) Volume = the amount of space an object takes up Measured in milliliters (mL) or centimeters cubed (cm3) There are three main states of matter. We determine the type of matter by its physical properties.

Classifying Matter Substance (pure): made up of only one kind of matter; every particle has the same fixed composition and properties a. Elements Smallest unit: atom Symbol: Au, Na, He, N b. Compounds: a substance that contains two or more elements chemically combined in a fixed proportion. Smallest unit: molecule Formula: C6H12O6, H2O Compounds can be broken down into simpler substances by chemical means. Elements cannot. The properties of a compound are different from the properties of the elements from which it was created – e.g. NaCl

Classifying Matter 2. Mixture: physical blend of two or more components. Example: salt-sand mixture The basic identity of each substance is not changed. Properties are not the same throughout. Composition is not fixed. Can be separated into its components by physical processes.

Heterogeneous: composition is not uniform throughout. Types of Mixtures Heterogeneous: composition is not uniform throughout. Often components are large enough to be seen. Example: Pizza Homogeneous: constant composition throughout, but the amount of each substance can vary. Examples: sugar water, vinegar Solutions: liquid or gaseous mixtures Alloys: solid solutions of metals Examples: steel, brass, bronze

Label as Substance or Mixture: If Substance, Element or Compound Label as Substance or Mixture: If Substance, Element or Compound? If Mixture, Hetero- or Homogeneous? 1. Salt water 2. vinegar 3. sugar 4. sodium 5. gasoline 6. bronze 7. orange juice & pulp 8. blood 9. baking soda 10. ethanol 11. vitamin C 12. hamburger 13. aluminum foil 14. iron 15. air 16. carbonated beverage 17. steel 18. sand and water 19. milk 20. dirt 21. table salt 22. lemonade

Physical Properties Physical Property: a characteristic of a substance that can be observed or measured without changing the substance’s composition. Examples: color, density, electrical conductivity, and physical state (solid, liquid, gas), solubility, freezing/melting point, boiling point, volatile Density: amount of matter (mass) contained in a unit of volume (density = mass/volume; [g/mL]) Solubility: the ability of one substance to dissolve in another. Volatile: describes substances that change to a gas easily at room temperature (ex. alcohol, gasoline)

You identify substances by their physical properties all the time. Extensive properties - Depends on the amount of matter in a sample. Ex. Mass, volume, length, etc. Intensive properties - an intensive property depends on the type of matter present. Ex. Color, luster, malleability, taste, reactivity. You identify substances by their physical properties all the time.

Physical Change Physical Change: a change in matter that does not involve a change in the identity of individual substances. Dissolving Changes in state

Chemical Properties Chemical Properties: the ability of a substance to react with other substances or to decompose. To determine the chemical properties of a substance, the substance must be allowed to react with other substances and therefore its composition will be changed. Examples: iron combines with oxygen at room temperature to produce rust sodium reacts explosively with water

Chemical Change Chemical Change (Chemical Reaction): the change of one or more substances into new substances. REACTANTS  PRODUCTS Involves the rearrangement of atoms. Law of Conservation of Mass: no atoms are created or destroyed during a chemical reaction. Mass of Reactants = Mass of Products

Label as a “physical” or “chemical” change. change in shape tarnish - physical – chemical rusting of iron grind - chemical Physical explode melt cutting a sheet of paper boil – physical breaking a crystal ferment corrode salt dissolving in water Bend Oxidize Burn - chemical condense - physical vaporize Rot Freeze decompose

Recognizing Chemical Changes Transfer of Energy -- Heat or Light is released or absorbed. Change in Color (drastic) Production of a Gas (excluding changes in physical state and dissolved gases – e.g. opening a carbonated soda) Formation of a Precipitate (a solid that forms and settles out of a liquid mixture – e.g. soap scum)

STATES OF MATTER & THEIR PROPERTIES What’s the ‘matter’ with you?

Solids Definite shape and volume Will not move (static) to fit container Will not flow Particles are together Low kinetic energy Low entropy - Entropy change has often been defined as a change to a more disordered state

Liquids Indefinite shape, definite volume. Will move to fit container Will flow. In most cases particles are more spread out Particles have higher KE Particles have higher entropy

Gases Indefinite shape, indefinite volume. Will move to fit container Will flow. Particles are spaced wide apart. Very high KE High entropy (chaotic, disordered)

Plasma Electrically charged gas. Will flow High KE High Entropy Ex. lightning

Physical Change When matter changes from solid to liquid or from liquid to solid, it is changing its physical state, therefore it is a physical change or phase change.

PHASE CHANGES MELTING FREEZING VAPORIZATION (boiling) CONDENSATION Solid  Liquid Liquid  Solid Liquid  Gas Gas  Liquid Solid  Gas Gas  Solid MELTING FREEZING VAPORIZATION (boiling) CONDENSATION SUBLIMATION DEPOSITION

MELTING POINT AND BOILING POINT Melting Point = MP Boiling Point = BP Example: Aluminum Melting Point = 660 oC Boiling Point = 2519 oC When would aluminum be considered a liquid? At what temperature would aluminum freeze? Between 660 & 2519 oC 660oC

Substance Melting Point (oC) Boiling Point (oC) Aluminum 660 2519 Methanol -94 65 Chlorine -101 -35 Oxygen -218 -183 Sodium chloride 801 1413 Zinc 420 907 Below -94oC When would methanol be in a solid state? _____ When would oxygen be in a liquid state? _____ When would sodium chloride be in a gas state? ______ Between -218oC and -183oC Above 1413oC

PHASE DIAGRAM Pressure Temperature LIQUID PHASE SOLID PHASE GAS PHASE B Pressure SOLID PHASE GAS PHASE A Temperature A – triple point B – critical point

PHASE DIAGRAMS Triple Point: the temperature and pressure at which three phases of a substance can coexist. Critical Point: critical temperature above which no amount of pressure can change the vapor into a liquid. Lines: indicate T and P at which two phases exist in equilibrium

A phase diagram is unique for each substance

Phase Diagram WATER: MP = 0oC BP = 100oC

What phase change occurs when carbon dioxide goes from B to A? Normal MP and BP means at standard pressure. Standard Pressure = 1 atm What phase change occurs when carbon dioxide goes from B to A? FREEZING

HEAT When a substance is heated its temperature increases until it changes state. When it changes state all energy is absorbed and the particles are pushed further apart. When a substance is cooled from liquid to solid heat (energy) is released and particles move closer together.

Phase Changes TEMPERATURE DOES NOT CHANGE DURING A PHASE CHANGE. All energy is going into pulling particles farther apart (increasing potential energy).

A substance that evaporates easily has a higher vapor pressure. Vapor Pressure: the pressure exerted by a vapor over a liquid in a closed container. A liquid in a sealed container evaporates until its vapor pressure is high enough that the rates of evaporation and condensation are equal. A substance that evaporates easily has a higher vapor pressure. Add pic

Vapor Pressure Example Ethanol is more volatile than water (evaporates more easily) and therefore has a higher vapor pressure. Ethanol vapors exert more pressure on its container at equilibrium. Water molecules are more polar than ethanol molecules. Why do you think water has a lower vapor pressure compared to ethanol?

Vapor Pressure Concepts (cont’d) Increasing the temperature of a liquid in a closed container increases the vapor pressure. Boiling point: the temperature of a substance when its vapor pressure = atmospheric pressure. Boiling point of a substance increases when the pressure on the liquid increases.

Thought Questions How does a pressure cooker work? increased pressure increases boiling point Why must foods cooked in boiling water at high altitudes be cooked longer? lower pressure lowers boiling point Why is a burn from steam at 100oC more severe than a burn from water at the same temperature? gas has more potential energy.