Page 64 Nov. 5, 2012 Focus: Chemical and Physical Properties / Changes Objective: pre-test, define physical and chemical property, physical and chemical change HW: article, data – analysis - graph due Warm-Up: Is Humpty Dumpty falling off the wall and cracking on the ground a physical or chemical change? Explain your answer.

Pre-Assessment / Formative Name November 5, 2012 Block Title: Formative of Objectives 6.P.2.3, 6.P.3.1, 6.P.3.3 No more than 25 minutes

Homework pg. 63 Science Fair Project Article and questions Bring back card for My Energy Kit

Physical versus Chemical Properties

Matter: anything that has mass and takes up space –Mass – the amount of matter in something –Volume – the amount of space something occupies Which of the following is matter? –A car? –A box? –You? Reviewing MATTER

What is a property? Property: a characteristic of a substance that can be observed

physics/chemistry/201

States, Boiling Point, Melting Point, and Solubility SolidGasLiquid

Defining States of Matter States of matter are NOT defined by what they are made of. –Example: solids can be elements (gold), compounds (Salt = NaCl), or mixtures (butter) Element (Au)Compound (NaCl)Mixture (Milk, Salt, etc)

Defining States of Matter States of matter are defined by whether they hold SHAPE and VOLUME Element (Au)Compound (NaCl)Mixture (Milk, Salt, etc) ALL KEEP THE SAME SHAPE AND VOLUME = Solids

Defining States of Matter Solids – have a definite SHAPE and VOLUME. Element (Au)Compound (NaCl)Mixture (Milk, Salt, etc) ALL KEEP THE SAME SHAPE AND VOLUME

Particle View of a Solid Particles in a solid are PACKED CLOSELY together and they are in a FIXED POSITION. Particles vibrate in place

Liquids Liquids – has definite VOLUME but no defined SHAPE 100 ml

Particle View of a Liquid Packed CLOSELY (like a solid), but move FREELY around each other (must stay in contact).

Gases Gases - do NOT have definite SHAPE or VOLUME. Bromine gas fills up the entire volume of the container

Particle view of a Gas Particles can MOVE FREELY and will either fill up or squeeze into available space.

Changes in States of Matter Thermal Energy – heat energy. More thermal energy = More particle movement

Changing States Solid Gas Liquid Increase Thermal Energy (Heat up) Decrease Thermal Energy (Cool off)

Melting point Melting - change from solid to liquid Melting point - SPECIFIC temperature when melting occurs. Each pure substance has a SPECIFIC melting point. –Examples: –M.P. of Water = 0°C (32°F) –M.P. of Nitrogen = °C ( °F) –M.P. of Silver = °C ( °F) –M.P. of Carbon = °C ( °F)

Melting Point Particles of a solid vibrate so fast that they break free from their fixed positions. Solid Liquid Increasing Thermal Energy Melting point

Vaporization Vaporization – change from liquid to gas Vaporization happens when particles in a liquid gain enough energy to form a gas. Gas Liquid Increasing Thermal Energy Boiling point

Two Kinds of Vaporization Evaporation – vaporization that takes place only on the surface of the liquid Boiling – when a liquid changes to a gas BELOW its surface as well as above.

Boiling Point Boiling Point – temperature at which a liquid boils Each pure substance has a SPECIFIC boiling point. –Examples: –B.P. of Water = 100°C (212°F) –B.P. of Nitrogen = °C ( °F) –B.P. of Silver = 2162 °C (3924 °F) –B.P. of Carbon = 4027 °C (7281 °F)

Boiling Point and Melting Point Melting point Boiling point

Solubility Maximum amount of a substance that can be dissolved in a liquid (at a specific temperature). Salt (NaCl) Water (H20) at 20°C

Solubility Solute – substance being dissolved Solvent – liquid substance that solute is dissolved into Salt (NaCl) Water (H20) at 20°C

Solubility Solute – ?????? Solvent – ????? Salt (NaCl) Water (H20) at 20°C Salt Water

Solubility can change Increased Temp = Increased Solubility Different substances have different solubility curves

Physical Property Physical property: a property that can be observed without changing the identity of the substance. Examples: luster malleability: the ability to be hammered into a thin sheet ductility: the ability to be stretched into a wire melting point boiling point density solubility specific heat

Special Physical Properties Melting point: the temperature at which a substance changes from a solid to a liquid at a given pressure water = 0 o C Boiling point: the temperature at which a substance changes from a liquid to a gas at a given pressure water = 100 o C

Chemical Properties Chemical property: a property that can only be observed by changing the identity of the substance Examples: flammability ability to rust reactivity with vinegar

Chemical Properties & Physical and Chemical Changes

Physical changes are those changes that do not result in the production of a new substance. If you melt a block of ice, you still have H 2 O at the end of the change.

If you break a bottle, you still have glass. Painting your nails will not stop them from being fingernails. Some common examples of physical changes are: melting, freezing, condensing, breaking, crushing, cutting, and bending.

Some, but not all physical changes can be reversed. You could refreeze the water into ice, but you cannot put your hair back together if you don’t like your haircut!

Special types of physical changes where any object changes state, such as when water freezes or evaporates, are sometimes called change of state operations.

CHEMICAL PROPERTIES Chemical properties can ONLY be observed AS the substances are changing into different substances.

Chemical changes, or chemical reactions, are changes that result in the production of another substance.

FLAMMABILITY: A material’s ability to BURN in the presence of OXYGEN

REACTIVITY: How readily (easily) a substance combines chemically with other substances.

When you burn a log in a fireplace, you are carrying out a chemical reaction that releases carbon. When you light your Bunsen burner in lab, you are carrying out a chemical reaction that produces water and carbon dioxide.

Common examples of chemical changes that you may be somewhat familiar with are; digestion, respiration, photosynthesis, burning, and decomposition.

Physical or Chemical Change? Painting Wood PHYSICAL

Physical or Chemical Change? Burning Paper CHEMICAL

Physical or Chemical Change? Digestion of food CHEMICAL

Physical or Chemical Change? Sugar dissolving in water PHYSICAL

Physical or Chemical Change? Iron turning red when heated PHYSICAL

Physical or Chemical Change? Evaporation PHYSICAL

Physical or Chemical Change? A pond freezing in winter PHYSICAL

Physical or Chemical Change? Melting ice PHYSICAL

Physical or Chemical Change? Cutting wire PHYSICAL

Physical or Chemical Change? Painting fingernails PHYSICAL

Physical or Chemical Change? Cutting fabric PHYSICAL

Physical or Chemical Change? Baking muffins CHEMICAL

Physical or Chemical Change? Shattering glass PHYSICAL

Physical or Chemical Change? Decomposition of old leaves CHEMICAL

Physical or Chemical Change? Wrinkling a shirt PHYSICAL

Physical or Chemical Change? An old nail rusting CHEMICAL

Density Density is the amount of mass per unit of volume. Density can be used to identify a substance. The density of water is 1.0g/mL

Density Calculations Calculations: D = m/V = g/mL = g/cm 3 Ex: A cube has a mass of 2.8 g and occupies a volume of 3.67 ml. Would this object float or sink in water? Mass = 2.8 gVolume = 3.67 mL D = 2.8g/3.67 mL= 0.76 g/mL –This object would float in water because its density is less than water (1.0 g/mL).

More Density Calculations Ex: A liquid has a mass of 25.6 g and a volume of 31.6 mL. Use the table below to identify the substance. M=25.6 gV=31.6 mL D = 25.6 g/31.6 mL D= 0.81 g/mL The substance is ethanol.

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