The Chemical Equation: A Chemical Recipe
Dr. Gergens - SD Mesa College
A. Learn the meaning of these arrows.
B.
The chemical equation is the shorthand notation for a chemical reaction. A chemical equation shows the
molar quantities of reactants and products in a reaction.
1 Reactants
react to produce
1Products
the number out in front of a substance in a balanced
reaction is a molar quantity known as a molar coefficient
B.
Law of Conservation of Mass - Matter cannot be gained or lost in the process of a chemical reaction.
The law of conservation of mass states that we must have a balanced equation.
C.
List five factors involved in the construction of an equation or "chemical recipe."
1.
The identity of products and reactants must be specified.
2.
Reactants are written to the left of the reaction arrow (————>) and products to the right.
3.
The physical state of reactants and products is shown in parentheses; (s), (l), (g), and (aq)
4.
The symbol ∆ over the reaction arrow mean that heat energy is necessary for the reaction to occur.
5.
The equation must be balanced.
Steps for balancing a chemical equation
Step 1:
Count the number of atoms of each element on both the product and reactant side.
Step 2:
Determine which atoms are not balanced.
Step 3:
Balance one atom at a time, using coefficients. Start with atoms that appear only once in the
reactants and only once in the products. Usually leave Hydrogen atoms followed by Oxygen atoms until last.
Step 4:
After you believe that you have successfully balanced the equation, repeat Step 1, to be certain
that mass conservation has been achieved.
Note: DO NOT Change subscripts in a molecular formula (i.e., 2 NaCl
X
Na2 Cl 2 )
119
Double Displacement Reactions Demonstration
Dr. Gergens - SD Mesa College
Using the solubility rules for ionic salts (see your periodic table, front cover), predict whether mixing
the two aqueous ionic salts (or aqueous strong acid) will produced an insoluble precipitate.
CuSO4 (aq)
NaNO3 (aq)
HCl (aq)
all soluble
all soluble
copper (II) sulfate CuSO4 (aq)
NaNO3 (aq)
sodium nitrate
hydrochloric acid
AgNO3 (aq)
all soluble
Ag2SO4 (s)
CuCO3 (s)
silver (I) sulfate
copper (II) carbonate
all soluble
all soluble
AgCl (s)
HCl (aq)
Na2 CO3 (aq)
H2O(l)+ CO 2 (g)
silver (I) chlroide
Ag2CO3 (s)
AgNO3 (aq)
silver (I) nitrate
silver (I) carbonate
sodium carbonate Na2 CO3 (aq)
A.
CuSO4 (aq)
+
NaNO3 (aq)
______>
No Reaction (NR)
B.
CuSO4 (aq)
+
HCl (aq)
______>
NR
C.
1 CuSO4 (aq)
D.
CuSO4 (aq)
E.
NaNO3 (aq)
F.
1 HCl (aq)
+
G.
2 HCl (aq)
+
H.
NaNO3 (aq)
+
I.
NaNO3 (aq)
+
+
+
2 AgNO3 (aq)
Na2 CO3 (aq)
+
HCl (aq)
1 AgNO3 (aq)
1 Na2 CO3 (aq)
AgNO3 (aq)
Na2 CO3 (aq)
______>
1 Ag2 SO4 (s)
______>
NR
______>
NR
______>
1 AgCl (s)
______>
______>
______>
+ 1 Cu(NO3)2 (aq)
+ 1 NaNO3 (aq)
2 NaCl (aq) + 1 CO2 (g) + 1 H2 O(l)
NR
NR
BALANCING PRACTICE
Dr. Gergens - SD Mesa College
a.
b.
c.
d.
1.
2.
3.
Balance each of the following equations by adjusting the coefficients in front of the chemical formulas.
List the physical state of each compound.
Determine the driving force for each reaction.
Classify each reaction in as many ways as possible.
2 AgNO3 (aq) ______>
reduced
silver (I) nitrate
Cu (s)
+
oxidized
copper metal
2 Al (s)
+
oxidized
aluminum metal
Na2 CO3 (aq) +
sodium carbonate
4.
5.
3 Fe (s)
oxidized
iron metal
+
3 S (s)
reduced
sulfur nonmetal
______>
CaCl 2 (aq)
______>
______>
Al 2 S 3
2 Ag
(s)
silver metal
copper (II) nitrate
CaCO3 (s)
Transfer of Electrons
Single Replacement
Redox
Transfer of Electrons
Combination (Synthesis)
Redox
(s)
+
2 NaCl
(aq)
sodium chloride
2 FeCl 3 (s)
Precipitation of CaCO3
Double Replacement
Transfer of Electrons
Combination (Synthesis)
Redox
iron (III) chloride
Ba 3 (PO4 )2 (s) +
barium phoshpate
barium chloride
sodium phosphate
+
calcium carbonate
______>
3 Cl2 (g)
reduced
chlorine gas nonmetal
3 BaCl2 (aq)
(aq)
aluminum sulfide
calcium chloride
2 Na3 PO4 (aq) +
Cu(NO3 )2
6 NaCl (aq) Precipitation of Ba3 (PO4 )2
sodium chloride Double Replacement
6.
2 NaOH (aq) +
CuSO4 (aq)
______>
Na2 SO4 (aq)
+
7.
Mg(OH)2 (s) +
H2 SO4 (aq)
______>
MgSO 4 (aq)
+
2 H2 O (l)
Water Formation
Double Replacement
Acid-Base Reaction
8.
2 Al (s)
oxidized
+
6 HCl (aq)
reduced
______>
2 AlCl 3 (aq)
+
3 H2 (g)
Hydrogen Gas Formation
Single Replacement
Redox
9.
3 Mg (s)
oxidized
+
2 H3 PO4 (aq)
reduced
______>
Mg 3 (PO4 )2 (s)
10.
Br 2 (l)
reduced
+
2 CuI (aq)
oxidized
______>
2 CuBr (aq)
+
I 2 (s)
11.
3 NaOH (aq) +
FeCl 3 (aq)
______>
3 NaCl
+
Fe(OH)3 (s) Precipitation of Fe(OH)3
Double Replacement
12.
2 KBr
Pb(NO3 )2 (aq) ______>
+
PbBr 2 (s)
Precipitation of PbBr 2
Double Replacement
Precipitation of Al 2 (SO4 )3
Double Replacement
13.
14.
15.
(aq)
+
(aq)
2 KNO3 (aq)
Cu(OH)2 (s) Precipitation of Cu(OH)2
Double Replacement
+ 3 H2 (g) Mg 3 (PO4 )2 ppt & H 2 Gas
Single Replacement
Redox
Transfer of Electrons
Single Replacement
Redox
2 AlCl 3 (aq) +
3 H2 SO4 (aq)
______>
Al 2 (SO4 )3 (s) +
6 HCl
Al 2 (SO4 )3 (aq) +
3 BaCl2 (aq)
______>
3 BaSO4 (s)
+
2 AlCl 3 (aq) Precipitation of BaSO4
Double Replacement
Cd(NO3 )2 (aq)
H2 S
______>
CdS (s)
+
2 HNO3 (aq) Precipitation of CdS
Double Replacement
+
(l)
(aq)
116
DOUBLE REPLACEMENT REACTIONS AND PREDICTIONS PRACTICE
Dr. Gergens - Mesa College
a.
b.
c.
Complete and balance each of the following equations for double replacement reactions.
List the physical state of each compound.
Determine the driving force for each reaction.
+
AgNO3 (aq)
______>
NaNO3 (aq)
+
AgCl
BaCl 2 (aq)
+
H2 SO4 (aq)
______>
BaSO4 (s)
+
2 HCl
3.
NaOH (aq)
+
HCl
______>
NaCl
+
H2 O (l)
Water Formation
4.
Na2 CO3 (aq)
+
2 HCl
______>
2 NaCl
+
H2 O (l)
+
5.
H2 SO4 (aq)
+
2 NaOH (aq)
______>
2 H2 O (l)
+
Na2 SO4 (aq)
6.
FeCl 3 (aq)
+
3 KOH (aq)
______>
Fe(OH)3 (s)
+
3 KCl (aq)
Precipitation of Fe(OH)3
7.
Na2 SO3 (aq)
+
2 HCl
______>
2 NaCl
+
H2 SO3 (l)
Special Strong to Weak Acid
8.
K2 CrO 4 (aq)
+
Pb(NO3 )2 (aq)
______>
2 KNO3 (aq)
+
PbCrO4 (s) Precipitation of PbCrO4
9.
NaC2 H3 O2 (aq) +
HNO3 (aq)
______>
HC2 H3 O2 (l)
+
NaNO3 (aq) Special Strong to Weak Acid
10.
NaOH (aq)
+
NH4 Cl
(aq)
______>
NaCl
(aq)
+
NH3 (g)
+
11.
2 BiCl 3 (aq)
+
3 H2 S
(l)
______>
Bi 2 S 3 (s)
+
6 HCl
Precipitation of Bi 2 S 3
12.
K2 C2 O4 (aq)
+
2 HCl
(aq)
______>
2 KCl (aq)
+
H2 C2 O4 (l) Special Strong to Weak Acid
13.
2 H3 PO4 (aq)
+
3 Ca(OH)2 (aq) ______>
6 H2 O (l)
+
Ca3 (PO4 )2 (s) Water & ppt of Ca3 (PO4 )2
14.
(NH4 )2 CO3 (aq) +
2 HBr
(aq)
______>
2 NH4 Br (aq)
+
H2 O (l)
+
15.
(NH4 )2 CO3 (aq) +
CaCl 2 (aq)
______>
2 NH4 Cl
+
CaCO3 (s)
Precipitation of CaCO3
1.
NaCl
2.
(aq)
(aq)
(aq)
(aq)
(aq)
(aq)
(aq)
(aq)
(s)
(aq)
(aq)
Precipitation of AgCl
Precipitation of BaSO4
CO2 (g) Water & Gas
Water Formation
H2 O (l) Water & Gas
CO2 (g) Water & Gas
117
MORE BALANCING PRACTICE
Dr. Gergens - Mesa College
a.
b.
c.
d.
1.
Balance each of the following equations by adjusting the coefficients in front of the chemical formulas.
List the physical state of each compound.
Determine the driving force for each reaction.
Classify each reaction in as many ways as possible.
2 Mg (s)
oxidized
+
2.
O2 (g)
reduced
______>
2 MgO (s)
2 KClO 3 (s)
reduced
oxidized
______>
2 KCl (s)
Transfer of Electrons
Combination (Synthesis)
Redox
+
3 O2 (g) Transfer of Electrons
Decomposition
Redox
3.
3 Fe (s)
oxidized
+
2 O2 (g)
reduced
______>
Fe3 O4 (s)
4.
Mg (s)
oxidized
+
2 HCl (aq)
reduced
______>
MgCl 2 (aq)
+
H2 (g)
Transfer of Electrons
Single Replacement
Redox
5.
2 Na (s)
oxidized
+
2 H2 O (l)
reduced
______>
2 NaOH (aq)
+
H2 (g)
Transfer of Electrons
Single Replacement
Redox
6.
3 Fe (s)
oxidized
+
4 H2 O (l)
reduced
______>
Fe3 O4 (s)
+
4 H2 (g) Transfer of Electrons
Single Replacement
Redox
Transfer of Electrons
Combination (Synthesis)
Redox
Beneath each word equation write the formula equation and balance it.
7.
2 S (s)
oxidized
+
O2 (g)
reduced
______>
SO2 (g)
8.
Zn (s)
oxidized
+
H2 SO4 (aq)
reduced
______>
ZnSO4 (aq)
9.
C (s)
oxidized
+
O2 (g)
reduced
______>
CO2 (g)
Transfer of Electrons
Combination (Synthesis)
Redox
10.
2 H2 (g)
oxidized
+
O2 (g)
reduced
______>
2 H2 O (l)
Transfer of Electrons
Combination (Synthesis)
Redox
11.
2 Al (s)
oxidized
+
6 HCl (aq)
reduced
______>
2 AlCl 3 (aq)
+
3 H2 (g) Transfer of Electrons
Single Replacement
Redox
12.
2 K (s)
oxidized
+
2 H2 O (l)
reduced
______>
2 KOH (aq)
+
H2 (g)
Transfer of Electrons
Single Replacement
Redox
13.
NaHCO3 (s)
+
H2 O (l)
+
CO2 (g)
Double Replacement
NO transfer of electrons
HC2 H3 O2 (aq) ______>
You can try this chemical reaction at home!
Transfer of Electrons
Combination (Synthesis)
Redox
+
NaC2 H3 O2 (aq) +
H2 (g)
Transfer of Electrons
Single Replacement
Redox
118
2.
a.
b.
3.
a.
2 AgNO3 (aq)
+
------->
2 AgBr (s)
+
Ca(NO3 )2 (aq)
2 Ag+ (aq) + 2 NO3 – (aq) + 2 Ca2+ (aq) + 2 Br– (aq) ------->
2 AgBr (s)
+
Ca2+ (aq) + NO3 – (aq)
Ag+ (aq)
CaBr 2 (aq)
Br– (aq)
+
NaCN (aq)
+
HCl (aq)
Na+ (aq) + CN– (aq) + H+ (aq)
b.
H+ (aq)
4.
AgCN (aq)
+
+
------->
------->
Cl – (aq)
+
------->
AgBr (s)
NaCl (aq)
+
HCN (g,aq)
+
HCN (g,aq)
Na + (aq) + Cl – (aq)
CN– (aq)
------->
HCN (g,aq)
HCl (aq)
------->
AgCl (s)
+
HCN (g,aq)
a.
Ag+ (aq) + CN– (aq)
+ H+ (aq) + Cl – (aq)
------->
AgCl (s)
+
HCN (g,aq)
b.
Ag+ (aq) + CN– (aq)
+ H+ (aq) + Cl – (aq)
------->
AgCl (s)
+
HCN (g,aq)
5.
a.
b.
6.
a.
b.
7.
a.
b.
8.
a.
b.
9.
Ba(OH)2 (aq)
+
Na2 SO4 (aq)
------->
Ba 2+ (aq) + 2 OH– (aq) + 2 Na+ (aq) + SO4 2– (aq) ------->
Ba 2+ (aq)
Na2 S (aq)
2 Na+ (aq) + S
2–
(aq)
Hg2+ (aq)
ZnCl 2 (aq)
+
SO4 2– (aq)
+
Hg(NO3 )2 (aq)
Na2 S (aq)
2 KC2 H3 O2 (aq)
H+ (aq)
+ 2 Na+ (aq) + 2 OH – (aq)
BaSO 4 (s)
------->
2 NaNO3 (aq)
+ Hg2+ (aq) + 2 NO3 – (aq) -------> 2 Na + (aq) + 2 NO3 – (aq) +
HgS (s)
+
+
S
2–
(aq)
------->
H2 S (aq, g)
+
+
S
2–
(aq)
+
S2– (aq)
+
H2 SO4 (aq)
------->
+
C2 H3 O2 – (aq)
+
2 NaCl (aq)
2 Na + (aq) + 2 Cl
(aq) ------->
------->
H 2 S (aq, g)
------->
K2 SO4 (aq)
------->
+
2 HCl (aq)
2 H + (aq) + 2 Cl – (aq)
ZnS (s)
------->
–
ZnS (s)
ZnS (s)
------->
2 HCl (aq)
2 H+ (aq) + 2 Cl
HgS (s)
------->
a. 2 K + (aq) + 2 C2 H3 O2 – (aq) + 2 H+ (aq) + SO4 2– (aq) ------->
b.
BaSO 4 (s)
------->
2 NaOH (aq)
HgS (s)
2 Na+ (aq) + S2– (aq) +
2 H+ (aq)
+
+
Zn2+ (aq) + 2 Cl – (aq) + 2 H+ (aq) + S2– (aq)
Zn2+ (aq)
BaSO4 (s)
–
+
H2 S (aq, g)
(aq) +
H2 S (aq, g)
2 K + (aq) + SO4 2– (aq)
HC 2 H3 O2 (l)
+
+
2 HC2 H3 O2 (l)
2 HC2 H3 O2 (l)
10.
HC2 H3 O2 (l)
+
a.
HC2 H3 O2 (l)
+
b.
C2 H3 O2 (l)
+
OH– (aq)
11.
NH4 OH (aq)
+
HCl (aq)
a.
NH4 + (aq) + OH– (aq)
+
KOH (aq)
K + (aq) +
OH– (aq)
H+ (aq) + Cl – (aq)
b.
H+ (aq)
+
OH– (aq)
12.
3 NH4 OH (aq)
+
FeCl 3 (aq)
a. 3 NH4 + (aq) + 3 OH– (aq) + Fe3+ (aq) + 3 Cl – (aq)
b.
13.
a.
Fe3+ (aq)
2 HNO3 (aq)
------->
H2 O (l)
+
KC2 H3 O2 (aq)
------->
H 2 O (l)
+
K + (aq) + C2 H3 O2 – (aq)
------->
H 2 O (l)
+
C 2 H3 O2 – (aq)
+
H2 O (l)
NH 4 + (aq) + Cl – (aq) +
H2 O (l)
------->
------->
------->
------->
NH4 Cl (aq)
H 2 O (l)
3 NH4 Cl (aq)
+
Fe(OH)3 (s)
-------> 3 NH 4 + (aq) + 3 Cl – (aq) +
Fe(OH)3 (s)
+
3 OH– (aq)
------->
+
Ca(OH)2 (aq)
------->
2 H2 O (l)
+
------->
2 H 2 O (l)
+ Ca 2+ (aq) + 2 NO3 – (aq)
2 H+ (aq) + 2 NO3 – (aq) + Ca2+ (aq) + 2 OH– (aq)
Fe(OH)3 (s)
Ca(NO3 )2 (aq)
b.
H+ (aq)
+
OH– (aq)
------->
H 2 O (l)
14.
2 AgNO3 (aq)
+
Na2 S (aq)
------->
Ag2 S (s)
+
2 Ag+ (aq) + 2 NO3 – (aq) + 2 Na+ (aq) + S2– (aq) ------->
Ag 2 S (s)
+ 2 Na + (aq) + 2 NO3 – (aq)
a.
b.
15.
a.
Ag+ (aq)
Cu(CN)2 (aq)
+
S2– (aq)
------->
Ag 2 S (s)
+
2 HCl (aq)
------->
CuCl 2 (aq)
Cu2+ (aq) + 2 CN– (aq) + 2 H+ (aq) + 2 Cl – (aq)
b.
H+ (aq)
+
16.
3 Pb(NO3 )2 (aq)
+
CN– (aq)
-------> Cu 2+ (aq) + 2 Cl – (aq)
2 NaNO3 (aq)
+
2 HCN (g,aq)
+
2 HCN (g,aq)
2 Al(NO 3 )3 (aq)
------->
HCN (g,aq)
------->
3 PbCl2 (s)
+
------->
3 PbCl 2 (s)
+ 2 Al3+ (aq) + 6 NO3 – (aq)
------->
PbCl 2 (s)
------->
Ag2 SO4 (s)
a. 2 Ag+ (aq) + 2 C2 H3 O2 – (aq) + Mg2+ (aq) + SO4 2– (aq) ------->
Ag 2 SO4 (s)
2 AlCl 3 (aq)
a. 3 Pb 2+ (aq) + 6 NO3 – (aq) + 2 Al 3+ (aq) + 6 Cl – (aq)
b.
17.
b.
Pb 2+ (aq)
+
2 AgC2 H3 O2 (aq) +
2 Ag+ (aq)
+
2 Cl – (aq)
MgSO 4 (aq)
SO4 2– (aq)
------->
Ag 2 SO4 (s)
+
Mg(C 2 H3 O2 )2 (aq)
+ Mg 2+ (aq) + 2 C2 H3 O2 – (aq)
18.
HC2 H3 O2 (l)
+
a.
HC2 H3 O2 (l)
+ NH 4 + (aq) + OH– (aq)
b.
19.
HC2 H3 O2 (l)
Fe(NO3 )3 (aq)
NH4 OH (aq)
+
+
OH– (aq)
H2 O (l)
+
------->
H 2 O (l)
+ NH4 + (aq) + C2 H3 O2 – (aq)
------->
H 2 O (l)
NH4 C2 H3 O2 (aq)
C 2 H3 O2 – (aq)
+
------->
FePO4 (s)
+
a. Fe3+ (aq) + 3 NO3 – (aq) + 3 K+ (aq) + PO4 3– (aq) ------->
FePO 4 (s)
+ 3 K + (aq) + 3 NO3 – (aq)
b.
Fe3+ (aq)
+
20.
Na2 CO3 (aq)
+
a.
K3 PO4 (aq)
------->
PO4 3– (aq)
H2 SO4 (aq)
2 Na+ (aq) + CO3 2– (aq) + 2 H+ (aq) + SO4 2– (aq)
b.
2 H+ (aq)
+
21.
Cu(NO3 )2 (aq)
+
CO3 2– (aq)
2 NaOH (aq)
a. Cu2+ (aq) + 2 NO3 – (aq) + 2 Na+ (aq) + 2 OH– (aq)
b.
Cu2+ (aq)
+
2 OH– (aq)
------->
------->
3 KNO3 (aq)
FePO 4 (s)
+
H2 O (l)
+
CO2 (g)
-------> 2 Na + (aq) + SO4 2– (aq) +
H2 O (l)
+
CO2 (g)
------->
Na2 SO4 (aq)
H 2 O (l)
------->
Cu(OH)2 (s)
------->
Cu(OH) 2 (s)
------->
Cu(OH) 2 (s)
+
CO2 (g)
+
2 NaNO3 (aq)
+ 2 Na+ (aq) + 2 NO3 – (aq)
Explain why each of the following mixing of reactants affords no reaction, NR.
22.
NaNO3 (aq)
+
23.
Pb(NO3 )2 (aq)
+
24.
CsCl (aq)
25.
K2 SO4 (aq)
HCl (aq)
------->
NR Both products are soluble
Hg(NO3 )2 (aq)
------->
NR Both products are reactants
+
(NH4 )2 SO4 (aq)
------->
NR Both products are soluble
+
NaClO4 (aq)
------->
NR Both products are soluble