P ROPERTIES OF M ATTER Chapter 15 Section 2

C LASSIFY THESE PROPERTIES AS PHYSICAL OR CHEMICAL. I F YOU AREN ’ T SURE, GUESS ! Color______________________________ Flammability ______________________________ Odor ______________________________ Shape ______________________________ Taste ______________________________ Density ______________________________ Melting Point ______________________________ Tendency to Rust______________________________ Reacts with light ______________________________ Boiling Point ______________________________ Volume ______________________________ Malleable ______________________________ Mass ______________________________ Magnetism ______________________________ Ductile ______________________________ Ability to dissolve______________________________

P HYSICAL P ROPERTIES A characteristic of a material that you can observe without changing the identity of the substance that makes up the material

P HYSICAL P ROPERTIES Physical Properties can be related to: Appearance What color is the item? What shape is the item? What is the item’s phase of matter? Behavior Does it attract a magnet? i.e. iron Can it be pulled into wires (ductile)? i.e. copper Can it be hammered into sheets (malleable)? i.e. gold At what temperature does it boil (boiling point)?

P HYSICAL P ROPERTIES Physical properties can be used to separate substances in a mixture How would you separate a mixture of iron, sand, and salt using physical properties?

C HEMICAL P ROPERTIES A characteristic of a material that indicates whether it can undergo a certain chemical change The result of the chemical change would be the production of a new substance Some examples: tendency of something to burn (flammability) i.e. lighter fluid, paint thinner tendency of something to react with light i.e. medicines that come in dark bottles like hydrogen peroxide (H 2 O 2 )

T RY THIS A GAIN ! C LASSIFY THESE PROPERTIES AS PHYSICAL OR CHEMICAL. I F YOU AREN ’ T SURE, GUESS ! Color______________________________ Flammability ______________________________ Odor ______________________________ Shape ______________________________ Taste ______________________________ Density ______________________________ Melting Point ______________________________ Tendency to Rust______________________________ Mass ______________________________ Boiling Point ______________________________ Volume ______________________________ Malleable ______________________________ Reacts with light______________________________ Magnetism ______________________________ Ductile ______________________________ Ability to dissolve______________________________ Physical Chemical Physical Chemical Physical Chemical Physical Chemical Physical

C LASSIFY THESE CHANGES AS PHYSICAL OR CHEMICAL. I F YOU AREN ’ T SURE, GUESS ! Evaporating water __________________________ Rust on an iron nail __________________________ Baking cookies __________________________ Dissolving salt in water __________________________ Hammering Aluminum into a sheet _________________ Cooking scrambled eggs _________________________ Burning a marshmallow __________________________ Melting an M&M in your mouth ____________________ Alka seltzer in water __________________________ Raising bread dough __________________________ Cutting an apple __________________________

P HYSICAL C HANGE A change in the size, shape, state of matter, etc. that does not change the identity of a substance A ph ase change is a ph ysical change even though energy may be removed or added to the substance In the new state of mater, the substance is still made of the same components, the atoms just have more or less energy i.e. if liquid water evaporates, it becomes water vapor if water vapor condenses, it becomes liquid water

P HASE C HANGES SOLID LIQUID GAS Melting Liquefying Evaporation Boiling Deposition Sublimation Freezing, Hardening, Solidifying Condensing

D ISTILLATION Distillation is a process that takes advantage of physical properties and physical changes to separate mixtures If two substances have different boiling points (temperature at which they boil), they can be separated. The mixture is heated slowly until it begins to boil. The vapors of the liquid with the lowest boiling point form first and are condensed and collected. If the other substance also needs to be collected, then the temperature is increased until the second liquid boils, condenses, and is collected

D ISTILLATION S ET -U P

C HEMICAL C HANGE The change of one substance into a new substance (chemical reaction) A chemical change alters the original chemical make-up of the substance

I NDICATIONS OF A C HEMICAL R EACTION How can you tell if a chemical change has taken place? ENERGY Evolution of heat, light, and/or sound (sometimes heat can be absorbed too) GAS A gas is produced, bubbles (effervescence) PRECIPITATE When solid particles form from 2 liquids COLOR – Unexpected Color change (i.e. clear liquid + clear liquid  purple liquid)

T RY THIS A GAIN ! C LASSIFY THESE CHANGES AS PHYSICAL OR CHEMICAL. I F YOU AREN ’ T SURE, GUESS ! Evaporating water __________________________ Rust on an iron nail __________________________ Baking cookies __________________________ Dissolving salt in water __________________________ Hammering Aluminum into a sheet _________________ Cooking scrambled eggs _________________________ Burning a marshmallow __________________________ Melting an M&M in your mouth ____________________ Alka seltzer in water __________________________ Raising bread dough __________________________ Cutting an apple __________________________ Physical Chemical Physical Chemical Physical Chemical Physical

L AW OF C ONSERVATION OF M ASS Matter is neither created nor destroyed during a chemical change (reaction) The mass of the substances present before the chemical change equals the mass of the substances that remain after the change Example Is burning wood a physical or chemical change? After a log burns, only ashes remain. Where do you think the rest of the mass went? Chemical change - Combustion Some mass left as solid particles in the smoke, some mass left as gas (CO 2 )

E XAMPLE OF C HEMICAL C HANGES What color was the Statue of Liberty when it was dedicated in 1886? NOT green! The Statue of Liberty is made of copper The copper at the surface has undergone a chemical change as the result of exposure to air and water. She is now covered in patina which is green!