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