warm up 5.4: determine if a chemical or physical change
DESCRIPTION
Warm Up 5.4: Determine if a Chemical or Physical Change. P. C. C. P. C. P. P. C. P. Physical change effects…. Size Shape Color State of matter Additionally…. Reversible No energy. Chemical Change effects…. Composition Additionally… Energy involved New substance formed - PowerPoint PPT PresentationTRANSCRIPT
1. An ice cube is placed in the sun. Later there is a puddle of water and then the puddle is gone.
2. Two chemical are mixed together and a gas is produce.3. A bicycle changes color as it rusts. 4. A solid is crushed to a powder. 5. Two substances are mixed and light is produced. 6. Mixing salt and pepper.7. Chocolate syrup is dissolved in milk.8. A marshmallow is burned over a campfire.
9. A marshmallow is cut in half.
Warm Up 5.4: Determine if a Chemical or Physical Change
PC
C
P
PP
P
C
C
Physical change effects….• Size• Shape • Color• State of matterAdditionally….• Reversible• No energy
Chemical Change effects…
• Composition Additionally…• Energy involved• New substance formed• Atoms rearranged
Signs of Chemical Change1. Color change2. Energy:
– Light– Heat– Fire– Electricity
3. Gas production: – Bubbles– Fizzing– Smoke– Odor change
4. Precipitate
Basics
Reactant
one or more substances
Change into New one or more substances
Product
Law of Conservation of Matter/Mass
• Matter is not created nor destroyed– Just rearranged
• Total mass of reactants = total mass of products
Symbols used in equationsAfter a chemical formula:(s) or ¯ : solid Cu(s) CaCo3 ¯(g) or : gas H2 (g) O2
(l) : liquid H2O(l)
(aq) : aqueous solution CaCl2 (aq)
dissolved in H2O
Other Symbols• or heat :heat supplied to rxn
• Chemical formula : catalyst
All chemical rxns have…. a change in energy
Ea: activation energy: Energy needed to start reactant collisions thus starting the rxnActivated Complex: “top of the hill” reactants’ atoms rearrange due to collisions.
H: Enthalpy: change in heat: products – reactants
Collision Theory ( 1:17 min)
Set up your paperEndothermic Exothermic
Sign Need 1 line
Descriptive words Need at least 2 lines
Drawingneed at least 6 lines
Reaction placementNeed 3 lines
Reaction path diagrams Need at least 10 lines
Endothermic ExothermicSign
Descriptive Words
Drawing
system heat
surroundings
system heat
surroundings
“ Into”, absorb, heat added; heat needed
Given off; heat produced; exit
EndothermicA + B + heat C orA + B C H= + kJ
ExothermicA + B C + heat orA + B C H= - kJ
Reaction placement
“ Endothermic Exothermic
Rxn Path diagram
Endothermic Exothermic
Reactants
ReactantsProducts
Products
Activated complex Activated complex
Ea Ea
H= + heat added
H= - heat given off
REACTIONS RATES
Catalyst
• speeds up rxn w/o being used • Less activation energy is needed• Lowers the activated complex
Other factors that effect rxn rate
• Increase Temperature• Increase Pressure • Increase Concentration – amount of a substance per area– Bigger M = more concentration • Which will cause a faster reaction: 3M or 0.4M 3M will make the rxn faster