PHYSICAL AND CHEMICAL CHANGES

Physical Changes In a physical change, the original substance still exists. It has only changed form. Energy changes usually do not accompany physical changes, except in phase changes and when substances dissolve.

Physical Changes Includes all changes of state (physical changes of a substance from one state to another)

Solid definite volume definite shape atoms are packed together in fixed positions strong attractive forces between the atoms only vibrate in place

Liquid definite volume indefinite shape atoms are close together atoms can overcome attractive forces to flow

Gases indefinite volume indefinite shape atoms move very quickly atoms are far apart pretty weak attractive forces

Changes of State

HEATING CURVE

Plasma high temperature state in which atoms lose their electrons Ex. the sun

Physical Changes: Separation Techniques Filtration- solid part is trapped by filter paper and the liquid part runs through the paper Vaporization- where the liquid portion is evaporated off to leave solid

Physical Changes: Separation Techniques Decanting- when liquid is poured off after solid has settled to bottom Centrifuge- machine that spins a sample very quickly so that components with different densities will separate

Physical Change: Separation Techniques Paper Chromatography- used to separate mixtures because different parts move quicker on paper than other

Physical Change: Dissolving of Salt

Physical Change: Boiling of Water

Physical Change: Melting of Ice

Physical Change: Cutting Grass

Physical Change: Ductile - Drawn or Stretched into Wire

Physical Change: Crushing a Rock

Physical Change: Condensation

Chemical Changes In a chemical change, a new substance is produced. Energy changes always accompany chemical changes.

Chemical Changes in Matter same as chemical reaction doesn’t change the amount of matter present (Conservation of Mass) reactants- substances that react products- substances that form

Energy Changes in Matter when any chemical change occurs, energy is always involved energy can be in different forms (light, heat, etc.) energy is never destroyed or created (law of conservation of energy)

Energy Changes in Matter Exothermic Reaction- reaction that gives off energy (feels warm on outside) Endothermic Reaction- reaction that uses up energy (feels cold on outside)

Chemical Change:Fireworks

Chemical Change:A Glow Worm Emits Light

Chemical Change: Rusting Chain

Chemical Change: Burning Candle

Chemical Change: Oxidation of Apples

Chemical Change: Plant Growing

Chemical Change: Rotting of Wood

Chemical Change: Burning of Magnesium

Fermenting of Grapes

Chemical Change: Tarnishing of Silver

Which of these represent a: (A) chemical change? (B) physical change? 1. combustion of gasoline 2. dissolving sugar in water 3. melting wax 4. rusting of iron 5. oxidation of apples

Which of these represent a: (A) chemical change? (B) physical change? 6. photosynthesis 7. digestion of food 8. grinding a rock 9. boiling of salt water 10. respiration

Which of these represent a: (A) chemical change? (B) physical change? 11. Acid on limestone produces carbon dioxide gas. 12. Milk sours. 13. Water is heated and changes to steam. 14. A pellet of sodium is sliced in two. 15. Sodium hydroxide dissolves in water.