Unit 5: Chemistry - Chemical Reactions Flashcards
Physical Change
Matter same state/identity/molecules
Physical Change Examples
- Changing Shape
- Change Size - cutting, etc
- Changing Temp - thermal expansion + contraction
- Changing Texture - smooth –> rough
- Mixing/Dissolving - mixing clay
- Phase Change (freezing/melting/boiling of water)
Chemical Change
Change in matter –> new matter (new identity)
Properties diff. than old matter
Matter change at moleular level
Chemical Reaction Vocabulary
Reactants (old) –> Products (new)
Catalyst - reaction happens faster without being part of it
Examples of Chemical Changes
- Explosion of fireworks
- Nail rusts
- Bread becomes toast
- Milk goes sour
- Digest food
- Paper on fire
The 7 Signs of a Chemical Change
- Gas (bubbles) or solid (precipitate) produced (not phase change)
- Color Change
- Temp. increased or decreased
- Light given off (emitted)
- Odor Produced
- Sound Produced
*Not all chemical changes meet requirements + often irrerservible
*Signs not proof of chemical change
What is the Law of Conservation of Mass?
- Matter neither created or destroyed in chemical reaction
- CLOSED SYSTEM mass of reactants = mass of products
- Matter (atoms/molecules) REARRANGED
In the Law of Conservation of Mass, why does it need to be a closed system?
Matter could escape if open system–> inaccurate results –> needs closed system
What is the order when atoms form new bonds?
Bonds between atoms break (separate) –> rearrange –> new bonds form
Chemical Change
Chemical Change = Reactant –> Product
Exothermic
Heat released + temp. increases
Endothermic
Heat absorbed + temp. decreases
Two families of chemicals
Acids + Bases
Chemical Equation
Equation to show chemical reaction
