Physical and Chemical Properties and Changes

Catalyst (10 min) Write down the answers to the following questions on a piece of notebook paper. This will be collected at the end of class for part of your daily grade How do you decide whether a sample of matter is a solid, liquid or gas (describe in terms of shape, volume, compressibility and particles) How is a solid similar to a liquid? How is a liquid similar to a gas? Assemble flip book (see sample at the front of the room)

Objectives SWBAT distinguish between the physical properties and chemical properties of matter SWBAT describe physical and chemical changes and classify changes of matter as physical or chemical

Agenda I do: lecture and frayer notes We do: distinguish between physical and chemical properties and changes on white boards You do: work with partners and classify the changes and properties of different substances

Characteristic(s)/Fact(s) Definition         Characteristic(s)/Fact(s)   Example(s) Vocabulary Word                          Illustration

Physical Property Definition: A characteristic that can be observed or measured without changing the sample’s composition Characteristics: Describes the substance itself Can be determined by viewing, touching or measuring the substance

Physical Property Examples: Melting/boiling point Density Electrical and heat conductivity Color Size or mass Luster (shine) Odor Hardness or Brittleness Temperature

Intensive vs. extensive physical property Intensive properties: Independent of the amount of substance present Extensive properties: Dependent upon the amount of substance present

chemical Property Definition: Ability of a substance to combine with or change into one or more other substances Characteristics: Cannot be determined just by viewing or touching the substance Internal structure of the substance must be changed to observe the property

Chemical Property Examples: Chemical stability Flammability How easily it reacts with other substances

Physical Change Definition: Changes which alter a substance’s physical appearance but the composition remains unchanged Characteristics: Can involve a change of state Does not change what the substance is

Physical Change Examples: Hair cut Boiling, freezing or melting a substance Sugar cube dissolving

chemical Change Definition: Change in which a substance is transformed to one or more new substances with altered compositions Characteristics: Involves a chemical reaction Changes color, smell, energy, formation of gas, precipitate and/or light

Observable factors of a chemical Change

Chemical Change Examples: Fireworks Burning coal Iron rusting Scientist breaking water into oxygen and hydrogen gas

Physical vs. chemical change Physical Change Chemical Change Does not involve changes in identity of a substance Change the identity of the substance Cause a change in state or shape Involves a chemical reaction, Causes a change on a molecular level Sometimes reversible Not reversible Does not yield a product Produce gases, solids, liquids, energy and color changes

Mercury oxide -> oxygen + Mercury

WE Do: Grab a white board for your group

Identify whether the following are physical or chemical changes and use your notes to explain why

Lighting a match

Crushing aluminum cans

Digesting food

Two cans of paint mixed together

Using hot glue

Mixing baking soda and vinegar

Water freezing and forming ice

Identify whether the following are physical or chemical properties and use your notes to explain why

Silver tarnishes when it comes in contact with hydrogen sulfide in the air

A banana is yellow

A sheet of copper can be pounded into a bowl

Gasoline is flammable

An apple will turn brown if left in oxygen

Acid in tomato sauce can corrode aluminum foil

Barium melts at 725 C

A sheet of copper can be pounded into a bowl

You do: identify chemical and physical properties and changes Read the packet and identify the physical and chemical properties and changes of the substance Make a table to record your answers

Homework # 2 Classify the following as chemical change (cc), chemical property (cp), physical change (pc), or physical property (pp). Explain WHY for each answer.   Heat conductivity Length of a metal object Combustible Brittleness Silver tarnishing Color Water freezing Cutting grass Melting ice Exploding dynamite Wood burning Baking bread Iron rusting Density of a coin

HOT Question 1 Tyreke made the following statement when speaking to his lab partners: "Breaking a rock into several pieces is an example of a chemical change. When I started, I had one substance (a rock). At the end, I had several different substances (the different sized pebbles).“ Assess the validity of his claim and justify your reasoning.

HOT Question 2 Water (H2O) is made of Hydrogen (a gas) and Oxygen (also a gas). Water is a liquid at room temperature. Based on this, it seems like hydrogen and oxygen combining to form water is a physical change (gases turning into solids). Do you agree with this assessment? Why or why not?

HOT Question 3 Chlorine is a yellowish gas at room temperature that reacts easily with sodium (a shiny silver metal) to form sodium chloride (NaCl-- table salt). Ingesting either chlorine or sodium alone will kill you. Ingesting table salt alone will just make you thirsty. Using your knowledge of physical and chemical changes, discuss whether you believe the formation of NaCl is more of a physical change or a chemical change.