unit 2 matter & change notes. is this a chemical or physical reaction? how do you know? atmq4

Unit 2 Matter & ChangeNotes

Is this a chemical or physical reaction? How do you know?

• http://www.youtube.com/watch?v=SJCcH0ATMQ4

Terms to Know

A. Chemistry- The study of matter and the changes matter undergoes.

Terms to Know

B. Mass- a measure of the amount of matter.

C. Matter –anything that takes up space and has mass.

Terms to Know

Three phases of matter:

solid – has definite shape and definite volume

liquid – no definite shape; definite volume

gas – no definite shape nor definite volume

Wait a minute! I have heard of a 4th state matter-

Plasma

Plasmas are a lot like gases, but the atoms are different because they are made up of free electrons and ions of the element.

Terms to Know

D. Atom– smallest particle of an element that retains the chemical

properties of the element

E. Element- a pure substance

made of only one kind of atom

-from the Periodic table

Terms to Know

F. Compound- composed of 2 or more elements in a fixed ratio

– properties differ from those

of individual elements

EX: table salt (NaCl)

II. Properties and Changes in Matter

A. Physical Properties of Matter characteristics which allow us to recognize and distinguish it from another substance

Without changing the substance!!!

– Examples of physical properties are color, odor, density, melting and boiling points and its physical state (solid, liquid, gas)

Physical Properties

• Malleable :

• Ability to be hammered into thin sheets

• Ductile:

• Ability to be drawn into a wire

• Luster:

• Ability to reflect the light

A. Properties and Changes in Matter

Intensive property – does NOT depend on amount of substance present; is constant, examples are density, melting or freezing points, heat capacity, solubility

Extensive property – depends on amount of matter present. Ex: mass, volume

** Intensive properties are so intense that the

amount of matter doesn’t matter!!***

II. Properties and Changes in Matter

B. Physical Changes of matter– does not alter the chemical composition of a substance. Physical changes usually are phase changes (going from solid to liquid) changes in size (cutting, grinding, etc), or dissolving in water.

II. Properties and Changes in Matter

• Know these 6 phase changes:

– Melting: Solid to liquid

– Evaporation/Boiling: liquid to gas

– Condensation: gas to liquid

– Freezing: liquid to solid

– Sublimation: solid to gas

– Deposition: gas to solid

Any change in state is a physical change…

A physical change is usually REVERSIBLE!!!

States of Matter

http://www.youtube.com/watch?v=xYFAj50c7xM

II.Properties and Changes in Matter

C. Chemical Properties – the manner in which a substance reacts with another substance – we can only observe a chemical property when it undergoes a chemical change.

Ex: Reactivity, flammability, heat of combustion, ability to oxidize

Write this down!

H2 + O2 H2O

Reactants Products

D. Chemical Changes of Matter

Involves changing one

substance into a new substance: cannot get the original substance back: burning, fermentation, cooking a steak, etc. A chemical change is

a chemical reaction.

II. Properties and Changes in Matter

1. Reactants: starting substances/before arrow

2. Products: ending substances/after arrow

Mg + 2 HCl MgCl2 + H2

Reactants products

5 Signs of a Chemical Reaction

• There are five indicators that a chemical reaction has taken place.

• They are…1. Color change2. Temp. change3. Gas.4. Appearance of a

precipitate (solid)5. Light.

Demo time!

• What are some of the signs that you see from the demos that indicate a CHEMICAL REACTION?

Law of Conservation of Mass

Law of conservation of Mass:

• The total mass of the reactants equals the total mass of the products. Matter is never created or destroyed.

Problem 1

Reactant A and reactant B are combined to form Product C. If there are 3 grams of reactant A and 5 grams of reactant B, how many grams of reactant C are formed?

Intensive or Extensive?1. Boiling point

Answer: Intensive

2. Melting point

Answer: Intensive

3. Color

Answer: Intensive

4. Odor

Answer: Intensive

5. Mass

Answer: Extensive

Physical or Chemical properties?

1. rusting iron

Answer: Chemical

2. dissolving in water

Answer: Physical

3. burning a log

Answer: Chemical

4. melting ice

Answer: Physical

5. grinding spices

Answer: Physical

Learning Check 3

9 mL of oxygen gas were added to 18 mL of hydrogen gas to form water vapor. How many mL of water vapor were formed?

Activity Time!!!!

Card Sorts – Making a T chart

Physical/ Chemical Changes

Physical Changes• Does NOT produce a

new substance• Is reversible

Chemical Changes• Produces a new

substance• Is NOT REVERSIBLE

Physical/Chemical Properties

Physical Properties• Does NOT require

altering the material• Does NOT require a

chemical change

Chemical Properties• Requires altering the

material• Requires a chemical

change

Intensive/Extensive Properties

Intensive Properties• Does NOT depend on

the amount of matter

Extensive Properties• Does depend on the

amount of matter