EVIDENCE of a CHEMICAL REACTION aka a CHEMICAL CHANGE T he decomposition of hydrogen peroxide H 2 O 2 2 H 2 O 2 2 H 2 O O 2 http wwwyoutubecomwatchv4N0m95PExHY ID: 551419
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Slide1
How do we make new molecules?Slide2
Yesterday we mixed stuff together…
Copy toner and Oil
Borax and Elmer’s GlueSlide3
Both mixtures underwent some change.
Copy toner and Oil
Borax and Elmer’s GlueSlide4
Both mixtures underwent some change.
Copy toner and Oil
Borax and Elmer’s Glue
But, which mixture was simply a solution and which one made a NEW MOLECULE? Slide5
Both mixtures underwent some change.
Copy toner and Oil
made an oily magnetic liquid
Borax and Elmer’s Glue
MADE A NEW MOLECULESlide6
illustrate with students
4 groups of 4 students holding hands represents 4 GLUE molecules Slide7
illustrate with students
4 BORAX molecules chemically combine their valence electrons with these glue molecules, making a larger
bloppier
moleculeSlide8
Both mixtures underwent some change.
Copy toner and Oil
JUST A PHYSICAL CHANGE
(LIKE SALT & WATER)
Borax and Elmer’s Glue
UNDERWENT CHEMICAL CHANGE!!
(NEW MOLECULES WERE FORMED)Slide9
To make
new molecules
, substances must go through
chemical change!Slide10
HOW DO WE KNOW A CHEMICAL CHANGE/REACTION HAS OCCURRED?Slide11
let’s go to one of the old classicsSlide12
BAKING SODA & VINEGAR (ACETIC ACID) REACTION
NaHCO
3
+ HC
2
H
3O2 NaC
2
H
3
O
2
+ H
2
O + CO
2
BAKING SODA
ACETIC ACID (VINEGAR)
REACTANTS
SODIUM ACETATE
WATER
CARBON DIOXIDE
PRODUCTSSlide13
What gas is produced?
BAKING SODA & VINEGAR (ACETIC ACID) REACTION
NaHCO
3
+ HC
2H
3O2 NaC2
H
3
O
2
+ H
2
O + CO
2
BAKING SODA
VINEGAR
REACTANTS
SODIUM ACETATE
WATER
CARBON DIOXIDE
PRODUCTSSlide14
What gas is produced? CO
2
BAKING SODA & VINEGAR (ACETIC ACID) REACTION
NaHCO
3
+ HC
2H3O
2
NaC
2
H
3
O
2
+ H
2
O +
CO
2
BAKING SODA
VINEGAR
REACTANTS
SODIUM ACETATE
WATER
CARBON DIOXIDE
PRODUCTSSlide15
Does FIRE need CO2
?
does carbon dioxide fuel a fire?Slide16
Does FIRE need CO
2
?
As a REACTANT?
does carbon dioxide fuel a fire?
NO!!!Slide17
Does FIRE need CO2
?
does carbon dioxide fuel a fire?
NO!!!
OXYGEN FUELS
A FIRE!Slide18
4Fe +
3O
2
à
2Fe
2
O3
C
3
N
6
H
6
O
6
+
O
2
3 CO
2
+ 2 H
2
O + 3 N
2
+
H
2
2CH
2
+
3O
2
à
2CO
2
+
2H
2
O
2C
4
H
10
+
13 O
2
à
8CO
2
+
10H
2
O
See how oxygen gas (
O
2
) is a reactant in all of these…
COMBUSTION & CORROSION NEED
OXYGEN
AS A REACTANT– THEREFORE,
WE CALL THESE OXIDATION REACTIONSSlide19
4Fe +
3O
2
à
2Fe
2
O3
C
3
N
6
H
6
O
6
+
O
2
3 CO
2
+ 2 H
2
O + 3 N
2
+
H
2
2CH
2
+
3O
2
à
2CO
2
+
2H
2
O
2C
4
H
10
+
13 O
2
à
8CO
2
+
10H
2
O
Which one is the rusting/corroding of iron?
COMBUSTION & CORROSION NEED
OXYGEN
AS A REACTANT– THEREFORE,
WE CALL THESE OXIDATION REACTIONSSlide20
4Fe +
3O
2
à
2Fe
2
O3 IRON RUSTING/CORRODING
C
3
N
6
H
6
O
6
+
O
2
3 CO
2
+ 2 H
2
O + 3 N
2
+
H
2
2CH
2
+
3O
2
à
2CO
2
+
2H
2
O
2C
4
H
10
+
13 O
2
à
8CO
2
+
10H
2
O
Which reaction seems to be the most sensitive/
tempermental
?
COMBUSTION & CORROSION NEED
OXYGEN
AS A REACTANT– THEREFORE,
WE CALL THESE OXIDATION REACTIONSSlide21
4Fe +
3O
2
à
2Fe
2
O3 IRON RUSTING/CORRODING
C
3
N
6
H
6
O
6
+
O
2
3 CO
2
+ 2 H
2
O + 3 N
2
+
H
2
2CH
2
+
3O
2
à
2CO
2
+
2H
2
O
2C
4
H
10
+
13 O
2
à
8CO
2
+
10H
2
O
Which one needs the least oxygen to make the most products?
COMBUSTION & CORROSION NEED
OXYGEN
AS A REACTANT– THEREFORE,
WE CALL THESE OXIDATION REACTIONSSlide22
4Fe +
3O
2
à
2Fe
2
O3 IRON RUSTING/CORRODING
C
3
N
6
H
6
O
6
+
O
2
3 CO
2
+ 2 H
2
O + 3 N
2
+
H
2
C4 EXPLOSION
2CH
2
+
3O
2
à
2CO
2
+
2H
2
O
2C
4
H
10
+
13 O
2
à
8CO
2
+
10H
2
O
That second reaction is the combustion/explosion of c4!!!
COMBUSTION & CORROSION NEED
OXYGEN
AS A REACTANT– THEREFORE,
WE CALL THESE OXIDATION REACTIONSSlide23
4Fe +
3O
2
à
2Fe
2
O3 IRON RUSTING/CORRODING
C
3
N
6
H
6
O
6
+
O
2
3 CO
2
+ 2 H
2
O + 3 N
2
+
H
2
C4 EXPLOSION
2CH
2
+
3O
2
à
2CO
2
+
2H
2
O
CANDLE WAX
BURNING
2C
4
H
10
+
13 O
2
à
8CO
2
+
10H
2
O
BUTANE LIGHTER
The last 2 are the combustion reactions for wax and butane.
COMBUSTION & CORROSION NEED
OXYGEN
AS A REACTANT– THEREFORE,
WE CALL THESE OXIDATION REACTIONSSlide24
4Fe +
3O
2
à
2Fe
2
O3 IRON RUSTING/CORRODING
C
3
N
6
H
6
O
6
+
O
2
3 CO
2
+ 2 H
2
O + 3 N
2
+
H
2
C4 EXPLOSION
2CH
2
+
3O
2
à
2CO
2
+
2H
2
O
CANDLE WAX
BURNING
2C
4
H
10
+
13 O
2
à
8CO
2
+
10H
2
O
BUTANE LIGHTER
If were on a submarine undersea, and you had only candles and butane to keep you warm, which would you use?
COMBUSTION & CORROSION NEED
OXYGEN
AS A REACTANT– THEREFORE,
WE CALL THESE OXIDATION REACTIONSSlide25
4Fe +
3O
2
à
2Fe
2
O3 IRON RUSTING/CORRODING
C
3
N
6
H
6
O
6
+
O
2
3 CO
2
+ 2 H
2
O + 3 N
2
+
H
2
C4 EXPLOSION
2CH
2
+
3
O
2
à
2CO
2
+
2H
2
O
CANDLE WAX
BURNING
2C
4
H
10
+
13
O
2
à
8CO
2
+
10H
2
O
BUTANE LIGHTER
If we’re
on a submarine undersea,
candles
uses up less oxygen in its reaction.
COMBUSTION & CORROSION NEED
OXYGEN
AS A REACTANT– THEREFORE,
WE CALL THESE OXIDATION REACTIONSSlide26
4Fe +
3O
2
à
2Fe
2
O3 IRON RUSTING
C
3
N
6
H
6
O
6
+
O
2
3 CO
2
+ 2 H
2
O + 3 N
2
+
H
2
C4 EXPLOSION
2CH
2
+
3O
2
à
2CO
2
+ 2H
2
O
CANDLE WAX
BURNING
2C
4
H
10
+
13 O
2
à
8CO
2
+
10H
2
O
BUTANE LIGHTER
oxygen helps rust, combust, fire-up & explode!!!
COMBUSTION & CORROSION NEED
OXYGEN
AS A REACTANT– THEREFORE,
WE CALL THESE OXIDATION REACTIONSSlide27
IF OXYGEN REACTANTS
(O
2
)
MAKE SOMETHING RUST/CORRODE
or COMBUST/EXPLODEthat’s a chemical reaction/change!Slide28
DUMB QUESTION:
ARE OXIDATION REACTIONS EXO OR ENDOTHERMIC?Slide29
DUMB QUESTION:
ARE OXIDATION REACTIONS EXO OR ENDOTHERMIC?
oxygen helps rust, combust, corrode & explode!
OXIDATION REACTIONS ARE
EXOTHERMICSlide30
4Fe +
3O
2
à
2Fe
2
O3 IRON RUSTING
C
3
N
6
H
6
O
6
+
O
2
3 CO
2
+ 2 H
2
O + 3 N
2
+
H
2
C4 EXPLOSION
2CH
2
+
3O
2
à
2CO
2
+ 2H
2
O
CANDLE WAX
BURNING
2C
4
H
10
+
13 O
2
à
8CO
2
+
10H
2
O
BUTANE LIGHTER
OXIDATION REACTIONS ARE
EXOTHERMIC
COMBUSTION & CORROSION NEED
OXYGEN
AS A REACTANT– THEREFORE,
WE CALL THESE OXIDATION REACTIONSSlide31
Fire extinguishers either release water or carbon dioxide foam.
Blanket or covering a fire stops the oxygen from reaching the flame.
To stop oxidation/combustion reactions, we shut off the supply of ________ gas reactant. Slide32
Fire extinguishers either release water or carbon dioxide foam.
Blanket or covering a fire stops the oxygen from reaching the flame.
To stop oxidation/combustion reactions, we shut off the supply of
oxygen
gas reactant. Slide33
4Fe +
3O
2
à
2Fe
2
O3 IRON RUSTING
C
3
N
6
H
6
O
6
+
O
2
3 CO
2
+ 2 H
2
O + 3 N
2
+
H
2
C4 EXPLOSION
2CH
2
+
3O
2
à
2CO
2
+ 2H
2
O
CANDLE WAX
BURNING
2C
4
H
10
+
13 O
2
à
8CO
2
+
10H
2
O
BUTANE LIGHTER
OXIDATION REACTIONS ARE EXOTHERMIC
COMBUSTION & CORROSION NEED
OXYGEN
without oxygen gas as a
reactant, the whole reaction STOPS!Slide34
Check for understanding…Slide35
Which gas can STOP combustion?
OXYGEN GAS (O
2
)
CARBON DIOXIDE (CO
2
)Slide36
Which gas can STOP combustion?
OXYGEN GAS (O
2
)
OMG…this STARTS the whole thing!!!
CARBON DIOXIDE (CO
2
)Slide37
Which has more atomic mass?
What’s a heavier molecule:
CO
2
or O
2?Slide38
Use your periodic tables!!!
What’s a heavier molecule:
CO
2
or O
2?Slide39
CARBON DIOXIDE
16+12+16
OXYGEN GAS
16+16
COMPARE MOLECULAR MASS!Slide40
CARBON DIOXIDE
16+12+16 = 44
OXYGEN GAS
16+16 = 32
Carbon dioxide
CO
2
is a heavier molecule!Slide41
Anyways…Slide42
Vinegar & baking soda reaction
NaHCO
3
+ HC
2H3O
2
NaC2H3O2
+ H
2
O + CO
2
Candle
wax burning
reaction
2CH
2
+ 3O
2
à
2CO
2
+ 2H
2
O
Let’s compare
Compare
reactions:Slide43
Vinegar & baking soda reaction
NaHCO
3
+ HC
2H3O
2
NaC2H3O2
+ H
2
O + CO
2
Candle
wax burning
reaction
2CH
2
+ 3O
2
à
2CO
2
+ 2H
2
O
What if I replaced
the
O
2
reactant
in
the
candle burning reaction with CO
2
?Slide44
Vinegar & baking soda reaction
NaHCO
3
+ HC
2H3O
2
NaC2H3O2
+ H
2
O + CO
2
Candle
wax burning
reaction
2CH
2
+ 3O
2
à
2CO
2
+ 2H
2
O
What if I replaced
the
O
2
reactant
in
the
candle burning reaction with CO
2
?
T
he reaction
would stop &
the flame would
go out!Slide45
That old classic reaction that’s where!
Where can I get a whole lot of carbon dioxide to find out!Slide46
YES!!!
BAKING SODA & VINEGAR (ACETIC ACID) REACTION
NaHCO
3
+ HC
2H
3O2 NaC2
H
3
O
2
+ H
2
O +
CO
2
BAKING SODA
VINEGAR
REACTANTS
SODIUM ACETATE
WATER
CARBON DIOXIDE
PRODUCTSSlide47
That old classic reaction that’s where!
And we Know now that CO
2
is a heavier gas compared to O2
!Slide48
Vinegar & baking soda reaction
NaHCO
3
+ HC
2H3O
2
NaC2H3O2
+ H
2
O + CO
2
Candle
wax burning
reaction
2CH
2
+ 3O
2
à
2CO
2
+ 2H
2
O
CO
2
pours into
the
beaker & replaces
the
O
2
reactant
in
the
candle reaction.
T
he reaction
stops & the
flame goes out!Slide49
Vinegar & baking soda reaction
NaHCO
3
+ HC
2H3O
2
NaC2H3O2
+ H
2
O + CO
2
Candle
wax burning
reaction
2CH
2
+ 3O
2
à
2CO
2
+ 2H
2
O
CO
2
pours into
the
beaker & replaces
the
O
2
reactant
in
the
candle reaction.
T
he reaction
stops & the
flame goes out!Slide50
Vinegar & baking soda reaction
NaHCO
3
+ HC
2H3O
2
NaC2H3O2
+ H
2
O + CO
2
Candle
wax burning
reaction
2CH
2
+ 3O
2
à
2CO
2
+ 2H
2
O
replace
the
O
2
reactant
WITH
HEAVIER
CO
2
SHUTS DOWN THE REACTION!.
T
he reaction
stops & the
flame goes out!Slide51
How did we know the baking soda reacted with the vinegar?Slide52
EVIDENCE of a CHEMICAL REACTION
(aka a
CHEMICAL CHANGE
)
1.
2.
a. b.
3.4.Slide53
EVIDENCE
of a CHEMICAL REACTION
(aka a
CHEMICAL CHANGE
)
a
GAS
is produced (fizzes up)
Slide54
Alka-Seltzer…Sodium Bicarbonate reaction
3 NaHCO
3
+ C
6
H
8O7
→ C
6
H
5
Na
3
O
7
+
3 CO
2
+
3 H
2
OSlide55
How did we know the candle burning was a combustion chemical reaction?Slide56
EVIDENCE of a CHEMICAL REACTION
(aka a
CHEMICAL CHANGE
)
a
GAS
is produced
a TEMPERATURE change
Slide57
Some chemical reactions RELEASE heat!
W_ _ m pack, butane l_ _ _
ter
, c_ _
dle, f_ _
ewor_ _, Slide58
Some chemical reactions RELEASE heat!
Warm pack, butane lighter, candle, fireworks, Slide59
SIGNS of a CHEMICAL REACTION
(aka a
CHEMICAL CHANGE
)
a
GAS
is produced
a TEMPERATURE change
temp heat
EXITS
reaction--
EXO
THERMIC
Slide60
Candle wax burning
reaction
2CH
2
+ 3O
2
à
2CO2 +
2H
2
O
+
HEAT
Hand warmers
4Fe
+ 3O
2
2Fe
2
O
3
+ heat
Potassium
permagneate
& glycerin
14 KMnO
4
+ 4 C
3
H
5
(OH)
3
7K
2
CO
3
+ 7Mn
2
O
3
+
5CO
2
+ 16H
2
O
+ HEAT
Heat is released during
EXOTHERMIC
chemical reactions.Slide61
SIGNS of a CHEMICAL REACTION
(aka a
CHEMICAL CHANGE
)
a
GAS
is created as a product
a TEMPERATURE
change
temp heat
EX
ITS
reaction—
EXO
THERMIC
oxidation—corroding & exploding
Slide62
How about PHOTOSYNTHESIS? Do phytoplankton and trees release OR absorb heat?
Slide63
With PHOTOSYNTHESIS, phytoplankton and trees ABSORB
the SUN’s heat
heat +Slide64
That’s partly why its cooler to lay on your lawn than on your driveway during the summer!Slide65
That’s why its cooler to walk through the shaded forest than a shaded garage.
trees absorb heat when doing photosynthesisSlide66
SIGNS of a CHEMICAL REACTION
(aka a
CHEMICAL CHANGE
)
a
GAS
is created as a product
a TEMPERATURE
change
temp heat
EX
ITS
reaction—
EXO
THERMIC
oxidation—corroding & exploding
temp heat
ENTERS
reaction-
ENDO
thermic
Slide67
Can you think of any
ENDOthermic
reactions that cool thing down in your home?Slide68
FRIDGES & AIR CONDITIONERS USE ENDOTHERMIC REACTIONS.Slide69
Check out this ENDOthermic reaction!
Barium hydroxide (
Ba(OH)
2
) mixed with ammonium chloride (
NH4Cl)…HEAT
+ Ba(OH)2 + 8 H2O +
2 NH4Cl → 2 NH3 + 10 H2O
+
BaCl
2
http
://
www.youtube.com/watch?v=5RJLvQXce4ASlide70
Some reactions ABSORB heat!
Barium hydroxide (
Ba(OH)
2
) mixed with ammonium chloride (NH
4Cl)…HEAT
Ba(OH)2
+ 8 H2O + 2 NH4Cl → 2 NH3
+
10 H
2
O
+
BaCl
2
COLD PACK
!
REFRIDGERATORS! PHOTOSYNTHESIS
!!!
http://www.youtube.com/watch?v=5RJLvQXce4ASlide71
what other signs do we have that a chemical reaction/change has occurred????Slide72
A BIG _ _ _ _ _ change is an OBVIOUS sign of chemical reaction & change.
_ _ _ _ _ change indicates a new substances has been formed…
first 1:14 of
http://
www.youtube.com/watch?v=ti_E2ZKZpC4
then 7:25-8:10Slide73
SIGNS of a CHEMICAL REACTION
(aka a
CHEMICAL CHANGE
)
a
GAS
is created as a product
a TEMPERATURE
change
temp heat
EX
ITS
reaction—
EXO
THERMIC
oxidation—corroding & exploding
temp heat
ENTERS
reaction-
ENDO
thermic
a
DRAMATIC
COLOR
change
Slide74
Sulfuric acid helps oxidizing sugar shows all 4 signs of a chemical change…BUT ESPECIALLY COLOR CHANGE!
http://www.youtube.com/watch?v=kcDSngXldB0
C
12
H
22
O
11 + 4 O2
4 CO
2
+ 8 C + 11 H
2
O
H
2
SO
4Slide75
Sulfuric acid helps oxidizing sugar shows all 4 signs of a chemical change…BUT ESPECIALLY COLOR CHANGE!
What role does sulfuric acid
H
2
SO
4 play in this chemical reaction?
C
12H22O
11
+ 4 O
2
4 CO
2
+ 8 C + 11 H
2
O
H
2
SO
4Slide76
Sulfuric acid helps oxidizing sugar shows all 4 signs of a chemical change…BUT ESPECIALLY COLOR CHANGE!
What role does sulfuric acid
H
2
SO
4 play in this chemical reaction?
C
12H22O
11
+ 4 O
2
4 CO
2
+ 8 C + 11 H
2
O
CATALYST
H
2
SO
4Slide77
Behold the GLOW STICK reaction!
C
14
H
10O
4 + H2O2 __C6
H6
O + C2O4Slide78
How many molecules of C6H6
O do we make here?
C
14
H
10O4 + H2
O2
__C6H6O + C2O4Slide79
Behold the GLOW STICK reaction!
C
14
H
10O
4 + H2O2 2
C6H
6O + C2O4Slide80
A BIG color change is an OBVIOUS sign of chemical reaction & change.
Color change indicates a new substances has been formed…
first 1:14 of
http://
www.youtube.com/watch?v=ti_E2ZKZpC4
then 7:25-8:10Slide81
SIGNS of a CHEMICAL REACTION
(aka a
CHEMICAL CHANGE
)
a
GAS
is created as a product
a TEMPERATURE
change
temp heat
EX
ITS
reaction—
EXO
THERMIC
oxidation—corroding & exploding
temp heat
ENTERS
reaction-
ENDO
thermic
a
DRAMATIC
COLOR
change
WHAT’S THE LAST SIGN?????
Slide82
corroded batteries and pennies…Slide83
SIGNS of a CHEMICAL REACTION
(aka a
CHEMICAL CHANGE
)
a
GAS
is created as a product
a TEMPERATURE
change
temp heat
EX
ITS
reaction—
EXO
THERMIC
oxidation—corroding & exploding
temp heat
ENTERS
reaction-
ENDO
thermic
a
DRAMATIC
COLOR
change
a
PRECIPITATE
forms
Slide84
But what is a PRECIPITATE?
http
://
www.youtube.com/watch?v=Q7fjH2G0y7wSlide85
Batteries are chemical reactions inside a metal shell or plastic box. When these reactions occur, often we get a precipitate.Slide86
SIGNS of a CHEMICAL REACTION
(aka a
CHEMICAL CHANGE
)
a
GAS
is created as a product
a TEMPERATURE
change
temp heat
EX
ITS
reaction—
EXO
THERMIC
oxidation—corroding & exploding
temp heat
ENTERS
reaction-
ENDO
thermic
a
DRAMATIC
COLOR
change
a
PRECIPITATE
forms
WHEN
REACTANTS TURN INTO NEW SOLID
PRODUCTS (change
in state)Slide87
nylon rope demoSlide88
END onto blue lab