1. Chapter 10 “Chemical Reactions”

2. LecturePLUS Timberlake
Physical Properties
color
melting point
boiling point
electrical conductivity
specific heat
density
state (solid, liquid, or gas)
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3. LecturePLUS Timberlake
Physical Change
Changes in physical properties
melting
boiling
condensation
No change occurs in the identity of the substance
Example:
Ice , rain, and steam are all water
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4. LecturePLUS Timberlake
Chemical Change
Atoms in the reactants are rearranged to form one or more different substances
Old bonds are broken; new bonds form
Examples:
Fe and O2 form rust (Fe2O3)
Ag and S form tarnish (Ag2S)
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5. LecturePLUS Timberlake
Learning Check E1
Classify each of the following as a
1) physical change or 2) chemical change
A. ____ a burning candle
B. ____ melting ice
C. ____ toasting a marshmallow
D. ____ cutting a pizza
E. ____ polishing silver
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6. LecturePLUS Timberlake
Solution E1
Classify each of the following as a
1) physical change or 2) chemical change
A. __2__ a burning candle
B. __1_ melting ice
C. __2__ toasting a marshmallow
D. __1__ cutting a pizza
E. __2__ polishing silver
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7. LecturePLUS Timberlake
Chemical Reaction
A process in which at least one new substance is produced as a result of chemical change.
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8. LecturePLUS Timberlake
A Chemical Reaction
Reactants Products
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9. LecturePLUS Timberlake
Learning Check E2
A. How does an equation indicate a change in
the identity of the reacting substances?
B. How did the yellow and green reactants
combine?
C. Did all the reactants form product? Why or
why not?
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10. LecturePLUS Timberlake
Learning Check E2
A. How does an equation indicate a change in
the identity of the reacting substances?
The formulas of the reactants are different
than the formulas of the products.
B. How did the yellow and green reactants
combine? 1 yellow combined with 1 green.
C. Did all the reactants form product? Why or
why not? No. There were more yellow
reactants than green.
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11. Symbols in equations? – Text page 278
the arrow (→) separates the reactants from the products (arrow points to products)
Read as: “reacts to form” or yields
The plus sign = “and”
(s) after the formula = solid: Fe(s)
(g) after the formula = gas: CO2(g)
(l) after the formula = liquid: H2O(l)

12. Symbols used in equations
(aq) after the formula = dissolved in water, an aqueous solution: NaCl(aq) is a salt water solution

13. Rules for balancing:
Balance the elements one at a time by adding coefficients (the numbers in front) where you need more TIP- save balancing the H and O until LAST!
(prefer to save O until the very last)

14. Never
Never change a subscript to balance an equation (You can only change coefficients)
If you change the subscript (formula) you are describing a different chemical.
H2O is a different compound than H2O2
Never put a coefficient in the middle of a formula; they must go only in the front
2NaCl is okay, but Na2Cl is not.

15. LecturePLUS Timberlake
Learning Check E5
Balance each equation. The coefficients for each equation are read from left to right
A. Mg N Mg3N2
1) 1, 3, ) 3, 1, ) 3, 1, 1
B. Al Cl AlCl3
1) 3, 3, 2 2) 1, 3, 1 3) 2, 3, 2
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16. LecturePLUS Timberlake
Learning Check E5
C. Fe2O C Fe CO2
1) 2, 3, 2, ) 2, 3, 4, ) 1, 1, 2, 3
D. Al FeO Fe Al2O3
1) 2, 3, 3, ) 2, 1, 1, ) 3, 3, 3, 1
E. Al H2SO Al2(SO4) H2
1) 3, 2, 1, ) 2, 3, 1, ) 2, 3, 2, 3
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17. LecturePLUS Timberlake
Solution E5
A. 3 Mg N2 Mg3N2
B. 2 Al Cl AlCl3
C. 2 Fe2O C Fe CO2
D. 2 Al FeO 3 Fe Al2O3
E. 2 Al H2SO Al2(SO4) H2
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18. 10.2 types of reactions

19. #1 – Synthesis Reactions
Synthesis= put together/create
2 substances combine to make one compound
SO3 + H2O ® H2SO4

20. #2 - Decomposition Reactions
decompose = fall apart
one reactant breaks apart into two or more elements or compounds.
NaCl Na + Cl2
CaCO CaO + CO2
Note that energy (heat, sunlight, electricity, etc.) is usually required

21. #2 - Decomposition Reactions
We can predict the products if it is a binary compound (which means it is made up of only two elements)
It breaks apart into the elements:
H2O
HgO

22. #2 - Decomposition Reactions
If the compound has more than two elements you must be given one of the products
The other product will be from the missing pieces
NiCO CO2 + ___
H2CO3(aq) ® CO2 + ___
heat

23. #3 - Single Replacement Reactions
One element replaces another
Reactants must be an element and a compound.
Products will be a different element and a different compound.
Na + KCl ® K + NaCl
F2 + LiCl ® LiF + Cl2
(Cations switched)
(Anions switched)

24. #3 Single Replacement Reactions
Metals will replace other metals (and they can also replace hydrogen)
K + AlN ®
Zn + HCl ®
Think of water as: HOH
Metals replace the first H, and then combines with the hydroxide (OH).
Na + HOH ®

25. #3 Single Replacement Reactions
We can even tell whether or not a single replacement reaction will happen:
Because some chemicals are more “active” than others
More active replaces less active
There is a list on page called the Activity Series of Metals
Higher on the list replaces those lower.

26. #4 - Double Replacement Reactions
Two things replace each other.
Reactants must be two ionic compounds, in aqueous solution
NaOH + FeCl3 ®
The positive ions change place.

27. #4 - Double Replacement Reactions
Have certain “driving forces”, or reasons
Will only happen if one of the products:
a) doesn’t dissolve in water and forms a solid (a “precipitate”), or
b) is a gas that bubbles out, or
c) is a molecular compound (which will usually be water).

28. How to recognize which type?
Look at the reactants:
E + E = Combination
C = Decomposition
E + C = Single replacement
C + C = Double replacement

29. #5 – Combustion Reactions
Combustion means “add oxygen”
Normally, a compound composed of only C, H, (and maybe O) is reacted with oxygen – usually called “burning”
If the combustion is complete, the products will be CO2 and H2O.
If the combustion is incomplete, the products will be CO (or possibly just C) and H2O.

30. Section 10.3 Reactions in Aqueous Solution

31. Net Ionic Equations
Many reactions occur in water- that is, in aqueous solution
When dissolved in water, many ionic compounds “dissociate”, or separate, into cations and anions
Now we are ready to write an ionic equation

32. Net Ionic Equations
Example (needs to be a double replacement reaction)
AgNO3 + NaCl  AgCl + NaNO3
1. this is the full balanced equation
2. next, write it as an complete ionic equation by splitting the compounds into their ions:
Ag1+ + NO31- + Na1+ + Cl1- 
AgCl + Na1+ + NO31-
Note that the AgCl did not ionize, because it is a “precipitate”

33. Net Ionic Equations
3. simplify by crossing out ions not directly involved (called spectator ions)
Ag1+ + Cl1-  AgCl
This is called the net ionic equation
Let’s talk about precipitates before we do some other examples