Chapter 9 balancing and types of chemical reactions
Ch 10 “The mole”
Chapter 11 now beginning (Stoichiometery)
There are MANY types of Chemical reactions; we will start with a few
Reactants  Products
(Read as reactants react to form Products)
Some reactions take in energy and are “endothermic”
Some reactions give off energy and are “exothermic”
Remember energy is in j (joules) or Kilojoules (kJ)
KNOW THE SEVEN DIATOMIC ELEMENTS!!!!!!!
(I2, Br2, Cl2, F2, O2, N2, H2)
( I Bring Clay For Our New House; Mr/Ms HOFBrINCl’s house)
A skeleton equation just has “the bare bones”, chemical formulas and
separated into reactants and products.
We need to “flesh out” what is happening by indicating phase (and perhaps
energy)
The phases (and symbol) we need to know are on page 283 of your chapter 9
reading
The phase symbols are:
(s) for a solid;
we will also see or use (ppt) for precipitate
(l) for a liquid (melted pure substance)
(g) for gas (or bubbles)
(aq) for an aqueous solution (one mixed in water)
There are also symbols for a catalyst, adding heat, etc that we will
encounter
Types of Chemical Reactions
Now that you know something about elements and compounds, lets see how they can react to for
different stuff! Just like with Lego’s (the snap together building blocks) you can put them
together, take them apart or swap them around.
1.
A DECOMPOSITION reaction starts with one reactant and ends up with two or
more products. Which of the following reactions are decomposition reactions? Circle
the letters.
a)
b)
c)
d)
e)
2.
NaCl  Na + Cl2
Na + Cl2  NaCl
H2O  H2 + O2
NaOH + HCl  HOH + NaCl
H2 + O2  H2O
A SYNTHESIS reaction starts with two reactants and ends up with one product.
Which of the following reactions are synthesis reactions? Circle the letters.
a)
b)
c)
d)
e)
3.
NaCl  Na + Cl2
Na + Cl2  NaCl
H2O  H2 + O2
NaOH + HCl  HOH + NaCl
K +Cl2  KCl
A SINGLE REPLACEMENT reaction starts with two reactants and ends up with
two products. The uncombined element takes the place of the combined element in the
compound. Which of the following reactions are single replacement reactions? Circle
the letters.
a)
b)
c)
d)
e)
4.
NaCl  Na + Cl2
NaOH + HCl  HOH + NaCl
K + AgCl2  Ag + KCl
Na + HCl  H2 + NaCl
H2O  H2 + O2
A DOUBLE REPLACEMENT reaction starts with two reactants and ends up with
two products. In this case both reactants are compounds and both products are
compounds. Which of the following reactions are double replacement reactions?
Circle the letters
a)
b)
c)
d)
e)
NaOH + HCl  HOH + NaCl
Na + HCl  H2 + NaCl
K + AgCl2  Ag + KCl
KOH + HNO3  KNO3 + HOH
Ca + S  CaS
5.
A COMBUSTION reaction is when the reactants are oxygen and a hydro carbon and
6.
the products are water and carbon dioxide.
A NEUTRALIZATION reaction is a special type of double replacement reaction that
will be covered in detail later on.
By now something should be bothering you about many of the Chemical
Equations listed above. Many of them ARE NOT BALANCED. Please follow the
teacher examples of how to balance equations.
Identifying and Balancing Chemical Equations
Name: _________________________________
period: ____
Balance these equations (even if the value is one put it in the blank) and identify
the type of reaction. (Synthesis, Decomposition, Single Replacement, Double Replacement or
Combustion)
Type of reaction
1. __HgO
__Hg + __O2
2. __ NaCl + __ AgNO3
3. __ Cl2 + __ Ca
____________
__NaNO3 + __AgCl
__ CaCl2
____________
____________
4. __ C2H6 + __ O2
__CO2 + __H2O
____________
5. __ H2O + __ Fe
__ Fe2O3 + __ H2
____________
6. __ Al2S3 + __Ca(OH)2
__ Al(OH)3 + __ CaS
____________
7. __ S8 + __ Fe
__ FeS
____________
8. __ N2 + __ H2
__ NH3
____________
__ KCl + __ O2
____________
9. __ KClO3
10. __ Al2(SO4)3 + __Ca(OH)2
__ Al(OH)3 + __ CaSO4 ____________
Glencoe Chapter 9 book problems (start on p288): 7-12
(Prentice Hall) Chapter 11 book problems: 1, 2, 3, 4, 11, 12, 14, 15, 18, 24, 28, 41, 49, 51, 54
Types of Chemical Reactions with answers
Now that you know something about elements and compounds, lets see how they can react to for
different stuff! Just like with Lego’s (the snap together building blocks) you can put them
together, take them apart or swap them around.
1.
A DECOMPOSITION reaction starts with one reactant and ends up with two or
more products. Which of the following reactions are decomposition reactions? Circle
the letters.
a)
b)
c)
d)
e)
2.
NaCl  Na + Cl2
Na + Cl2  NaCl
H2O  H2 + O2
NaOH + HCl  HOH + NaCl
H2 + O2  H2O
A SYNTHESIS reaction starts with two reactants and ends up with one product.
Which of the following reactions are synthesis reactions? Circle the letters.
a)
b)
c)
d)
e)
3.
NaCl  Na + Cl2
Na + Cl2  NaCl
H2O  H2 + O2
NaOH + HCl  HOH + NaCl
K +Cl2  KCl
A SINGLE REPLACEMENT reaction starts with two reactants and ends up with
two products. The uncombined element takes the place of the combined element in the
compound. Which of the following reactions are single replacement reactions? Circle
the letters.
a)
b)
c)
d)
e)
4.
NaCl  Na + Cl2
NaOH + HCl  HOH + NaCl
K + AgCl2  Ag + KCl
Na + HCl  H2 + NaCl
H2O  H2 + O2
A DOUBLE REPLACEMENT reaction starts with two reactants and ends up with
two products. In this case both reactants are compounds and both products are
compounds. Which of the following reactions are double replacement reactions?
Circle the letters.
a)
b)
c)
d)
e)
NaOH + HCl  HOH + NaCl
Na + HCl  H2 + NaCl
K + AgCl2  Ag + KCl
KOH + HNO3  KNO3 + HOH
Ca + S  CaS
5.
A COMBUSTION reaction is when the reactants are oxygen and a hydro carbon and
6.
the products are water and carbon dioxide.
A NEUTRALIZATION reaction is a special type of double replacement reaction that
will be covered in detail later on.
By now something should be bothering you about many of the Chemical
Equations listed above. Many of them ARE NOT BALANCED. Please follow the
teacher examples of how to balance equations.
Identifying and Balancing Chemical Equations
Name: _______ANSWERS_________
period: ____
Balance these equations (even if the value is one put it in the blank) and identify
the type of reaction. (Synthesis, Decomposition, Single Replacement, Double Replacement or
Combustion)
Type of reaction
1. _2_HgO +
_2_Hg + _1_O2
2. _1_ NaCl + _1_ AgNO3
3. _1_ Cl2 + _1_ Ca
__Decomposition_
_1_NaNO3 + _1_AgCl
_1_ CaCl2
4. _2_ C2H6 + _7_ O2
_4_CO2 + _6_H2O
5. _3_ H2O + _2_ Fe
_1_ Fe2O3 + _3_ H2
6. 1 Al2(SO4)3 + 3 Ca(OH)2
_Double Replace_
___Synthesis___
__combustion___
_single replacement_
2 Al(OH)3 + 3 CaSO4 _Double Replace_
7. _1_ S8 + _8_ Fe
_8_ FeS
___ Synthesis __
8. _1_ N2 + _3_ H2
_2_ NH3
__ Synthesis __
9. _2_ KClO3
_2_ KCl + _3_ O2
10. 1 Al2(SO4)3 + 3 Ca(OH)2
__Decomposition_
2 Al(OH)3 + 3 CaSO4 __Double Replace_
Review warm-up for the limiting reagents part of Stoichiometery
Review: What type of reactions are these?
1) NaOH + KNO3 --> NaNO3 + KOH
2) CH4 + 2 O2 --> CO2 + 2 H2O
3) 2 Fe + 6 NaBr --> 2 FeBr3 + 6 Na
4) CaSO4 + Mg(OH)2 --> Ca(OH)2 + MgSO4
5) NH4OH + HBr --> H2O + NH4Br
6) Pb + O2 --> PbO2
7) Na2CO3 --> Na2O + CO2
- Skeletal equation (bare bones)
- Balanced equation (minimum necessary to do stoichiometry calculations)
- Balanced equation with phase information
o (solid (s), liquid (l), Gas(g), aqueous solution (aq))
- (Equations where everything is written as ions, elements or
molecules help you understand how to balance the compounds
and then the equation)
- Net ionic equations: then you strip away any ion that stay in
solution from the
Chapter 11 book problems: 1, 2, 3, 4, 11, 12, 14, 15, 18, 24, 28, 41, 49, 51, 54
Book problem answers:
1)
Solid sodium metal and liquid water react to form a solution of sodium hydroxide
and bubbles of hydrogen gas.
2)
S(s) + O2(g)  SO2 (g) but you might not know this
3)
a)
2 AgNO3 + H2S  Ag2S + 2 HNO3
b)
3 Zn(OH)2 + 2 H3PO4  Zn3(PO4)2 + 6 H2O
4)
a)
b)
H2 + S  H2S
FeCl3 + Ca(OH)2  Fe(OH)3 + CaCl2
11)
a)
b)
Fe(s) + Cl2(g)  FeCl3(s)
Al2(CO3)3(s)  Al2O3(s) + CO2(g)
12)
a) 2 SO2 + O2  2 SO3
b) Fe2O3 + 3 H2  2 Fe + 3 H2O
c) 4 P + 5 O2  P4O10
d) 2 Al + N2  2 AlN
14)
3 Mg(s) + N2(g)  Mg3N2
15)
Complete and balance this decomposition reaction:
2 HI  H2 + I2
; remember diatomic elements (I Br Cl F O N H)
18)
Write the products of these double-replacement reactions. Then Balance
each equation.
a) 3 NaOH(aq) + Fe(NO3)3(aq)  Fe(OH)3(s) + 3 NaNO3
b) 3 Ba(NO3)2(aq) + 2 H3PO4(aq)  Ba3(PO4)2(s) + 6 HNO3(aq)
24)
28)
Classify and balance each:
a) 2 C3H6 + 9 O2  6 CO2 + 6 H20
b) 2 Al(OH)3  Al2O3 + 3 H2O
c) Li + O2  Li2O
d) Zn + 2 AgNO3  2 Ag + Zn(NO3)2
Write the balanced net ionic equation for this reaction. (as written)
Ca2+(aq) + OH-(aq) + H+(aq) + PO4-3(aq) 
Ca2+ + PO43-(aq) + H2O(l)
You just don’t write the stuff that is on both sides: so…
Ca2+(aq) + OH-(aq) + H+(aq) + PO4-3(aq) 
Ca2+ + PO43-(aq) + H2O(l)
Or simplified it is:
41)
49)
reactions
combustion
decomposition
synthesis
single replacement
OH-(aq) + H+(aq) 
H2O(l)
Balance each :
a) a bb team:
C + 2 F + 2 G  CF2G2
b) a tricycle: F + 3 W + S + 2 P  FW3SP2
Write a balanced equation for each of the following double replacement
a) H2C2O4(aq) + KOH(aq)  K2C2O4 + 2 HOH
b) CdBr2(aq) + Na2S(aq)  CdS(s) + 2 NaBr(aq)
51)
Write a balanced equation for the complete combustion of each compound
a) C4H8 + 6 O2  4 CO2 +4 H2O
b) C3H6O + 4 O2  3 CO2 + 3 H2O ; (the reactant also has oxygen)
54)
Write a net ionic equation for each of the following reactions.
a) 2 HCl(aq) + Ca(OH)2(aq)  CaCl2 + 2 HOH
as ions it is written as:
2 H+ + 2Cl- + Ca2+ + 2(OH)-  Ca2+ + 2Cl- + 2H2O ; water’s
a molecule not an ionic compound
Cross out the ions that are on both sides gives us:
+
2 H + 2Cl- + Ca2+ + 2(OH)-  Ca2+ + 2Cl- + 2H2O
Or 2 H+ + 2(OH)-  2H2O ( the net ionic equation)
b) AgNO3(aq) + AlCl3(aq)  silver chloride is a precipitate
so… 3 AgNO3(aq) + AlCl3(aq)  3 AgCl(s) + 1 Al(NO3)3(aq)
as ions it is:
3 Ag+ + 3 (NO3)-(aq) + Al3+ + 3Cl-(aq)  3 AgCl(s) + 1 Al3+ + 3(NO3)-(aq)
Cross out the same ones to get net ionic:
3 Ag+ + 3 (NO3)-(aq) + Al3+ + 3Cl-(aq)  3 AgCl(s) + 1 Al3+ + 3(NO3)-(aq)
Or simply:
3 Ag+
+ 3Cl-(aq)  3 AgCl(s) (the net ionic equation)
The activity series of metals
Chemical Equations
Name: _________________________________
Look at the activity series for metals on page 333 of you text; (or
at the following table)
Note: decreasing activity top to bottom

Metals from Li to Na will replace H
from acids and water; From Mg to
Pb they will replace H from acids
only
Predict if any reaction will take place. Balance the equations or
any reaction that will occur
11.
Mg(s) + FeSO4 (aq)
12.
Mg(s) + NaCl (aq)
13.
Fe(s) + Pb(NO3)2 (aq)
14.
Cu(s) + Al2(SO4)3 (aq)
15.
Ag(s) + ZnS (aq)
16.
Zn(s) + H2O (l)
17.
Ag(s) + H2SO4 (aq)
18.
Fe(s) + HCl (aq)
19.
Na(s) + H2O (l)
20.
Pb(s) + H2O (l)
21.
Li(s) + Mgl2 (aq)
22.
Al(s) + HCl (aq)
period: ____
Name
Lithium
Potassium
Calcium
Sodium
Magnesium
Aluminum
Zinc
Iron
Lead
(hydrogen)
Copper
Mercury
Silver
Symbol
Li
K
Ca
Na
Mg
Al
Zn
Fe
Pb
H
Cu
Hg
Ag


The seven diatomic elements


H2, N2, O2, F2, Cl2, Br2, I2


When in their natural state (gases since most have very low boiling points) these elements
“pair up” into molecules (non-metal to non-metal). They seem to do this to have a
complete valence shell. You must have these memorized in order to properly write
balanced chemical equations. Here are some tricks I have learned.


An oldie but a goodie

I Bring Clay For Our New House

( 4 paving 8 sidewalks; P4 S8 )


One teacher said all the elements got together to honor to honor a
great chemistry Ms.
(or Mr.) HOFBrINCl
(spell it just like
it sounds)


One particularly energetic cheerleader noticed that it was
and a hockey stick (3 across and 4 down N,
O, F, Cl, Br, I).


H (hockey puck)
However you wish to memorize them JUST DO IT !!!