Chemistry 6.0
Chapter 8 – Chemical Equations
Name________________________________
Chemical Equations Introduction:
Write complete equations for the following:
1. Two moles of solid sodium chloride decompose when exposed to an electric current into two
moles of sodium metal and 1 mole of chlorine gas.
2. One mole of barium chloride in solution reacts with one mole of sodium sulfate in solution to
produce 1 mole of solid barium sulfate and 2 moles of sodium chloride in solution.
3. Two mole of solid potassium chlorate, when heated, decompose into two moles of solid potassium
chloride and 3 moles of oxygen gas.
4. One mole of solid calcium carbonate decomposes when heated into one mole of solid calcium
oxide and 1 mole of carbon dioxide gas.
5. Two moles of solid aluminum hydroxide decomposes when heated into one mole of solid
aluminum oxide and three moles of water vapor.
6. One mole of zinc metal when mixed with two moles of a hydrochloric acid solution react and
produce one mole of zinc chloride in solution and one mole of hydrogen gas.
7. Eight moles of fluorine gas are bubbled through a solution containing eight moles of potassium
sulfide and react to produce sixteen moles of potassium fluoride in solution and one mole of solid
sulfur.
2
Balancing Equations: Balance the following reactions. Place a “B” at the beginning of any that are
balanced as written.
8.
_____ Zn + _____O2
→
_____ZnO
9.
_____HI → _____H2
+
10.
_____B + _____F2 → _____BF3
11.
_____N2 + _____H2 → _____NH3
12.
_____Fe + _____H2O → _____Fe3O4 + _____H2
13.
_____BaCl2 +
14.
_____P4 +
15.
_____KClO3 →
16.
_____C3H8
17.
_____Cu +
_____AgNO3 →
18.
_____Te +
_____H2O →
19.
_____La(NO3)3 +
20.
_____RhO3 →
21.
_____Hf +
_____N2 →
22.
_____Ga +
_____H2SO4 →
23.
_____PdCl2 +
_____HNO3 →
24.
_____RbBr +
_____AgCl →
25.
_____PaI5
_____I2
_____H2SO4 →
_____O2 →
+
→
_____HCl
_____P4O10
_____KCl +
_____O2
_____BaSO4 +
_____O2
→
_____CO2 +
_____Cu(NO3)2 +
_____TeO +
_____NaOH →
_____RhO +
_____Pa +
_____H2O
_____Ag
_____H2
_____La(OH)3 +
_____NaNO3
_____O2
_____Hf3N4
_____Ga2(SO4)3 +
_____H2
_____Pd(NO3)2 +
_____AgBr +
_____I2
_____HCl
_____RbCl
3
26.
Na +
O2 →
Na2O
27.
H2 +
O2 →
H2 O
28.
Na2SO4 +
CaCl2 →
29.
Al2O3 →
Al +
30.
C2H6 +
O2 →
CO2 +
31.
SO3 +
H2O →
H2SO4
32.
SiCl4 →
33.
C +
34.
Br2 +
NaI →
NaBr +
I2
35.
Zn +
HCl →
ZnCl2 +
H2
36.
H2S +
O2 →
37.
Ba(NO3)2 +
38.
C5H12 +
O2 →
CO2 +
39.
HgO →
Hg +
O2
40.
H2SO4 +
Pb +
41.
C6H12O6 +
42.
Ca +
43.
C6H12O6 →
C2H5OH +
44.
HC2H3O2 +
NaHCO3 →
45.
NaCl +
SO2 +
46.
Fe2O3 +
CO →
47.
Ca3(PO4)2 +
Si +
H2 →
CaSO4 +
NaCl
O2
H2O
Cl2
CH4
H2 O +
SO2
Na2SO4 →
C +
PbSO4 +
CO2 +
H2O
H2O
Ca(OH)2 +
H2O
NaNO3
H2O
PbO2 →
O2 →
H2O →
BaSO4 +
H2
CO2
CO2 +
+ O2 →
CO2 +
SiO2 →
NaC2H3O2 +
Na2SO4 +
H2O
HCl
Fe
CaSiO3 +
CO +
P4
4
48. aluminum
+
49. chromium(III) hydroxide
+ nitric acid

50. chromium + hydrobromic acid
51. krypton difluoride
CH3OH
+
O2

54.
Si2H6
+
O2

55.
CH3NH2
+
O2
56.
Na2SiO3
+
57.
NH3
58.
Sb2S3
59.
Al
60.
C2H5Cl

water
+
hydrochloric acid
53.
aluminum chloride
+
chromium (III) bromide
water  krypton
+
52. chlorine + water 
+

hydrochloric acid
+
oxygen
+
hydrogen
chromium(III) nitrate
+
hydrogen
+ hydrofluoric acid
oxygen
+
H2O
SiO2
+
H2O

CO2
+
H2O
+
N2
HF

H2SiF6
+
NaF
+
H2O
+
O2

NO
+
H2O
+
HCl

H3SbCl6
+
H2S
+
H2O
+
H2
NaOH
+
NaPb 
CO2

(C2H5)4Pb
NaAl(OH)4
+
NaCl
+
Pb
5
Types of Reactions: Balance the following equations and indicate the type of reaction on the line
provided.
→
61.
NaCl
Na +
62.
Na
63.
C2H4
+
64.
H2O
→
65.
H2
66.
C8H18
67.
NaOH
68.
Na
69.
K
70.
K +
AgCl
71.
C6H12
+
72.
Ca
73.
KOH +
74.
Al
75.
HgO
76.
NaOH
+
77.
Fe +
O2 →
78.
C6H8 +
O2
→
79.
Pb(NO3)2
+
K2CrO4 →
80.
H2
81.
C3H5(NO3)3
Cl2 →
+
O2
+
+
H2O
_____________________
→
→
→
→
_____________________
NaCl
_____________________
KCl
+
_____________________
H2O
_____________________
_____________________
H2O +
KNO3
_____________________
Al2O3
_____________________
O2
_____________________
H2SO4 →
→
NaCl
_____________________
CO2
→
Hg +
N2
_____________________
CaS
HNO3
→
H2O
+
Ag +
→
O2
+
_____________________
KCl
→
S8
H2O
H2O +
H2
→
+
CO2
→
O2
+
+
_____________________
HCl
Cl2
+
O2
→
HCl
+
_____________________
+
O2
+
NaCl
CO2
→
O2
_____________________
→
H2
+
Cl2
Na2SO4
+
H2O
_____________________
Fe2O3
CO2
_____________________
+
H2O
PbCrO4 +
_____________________
KNO3
NH3
CO2 +
_____________________
_____________________
N2 +
H2O +
O2
_____________________
6
Decomposition, Synthesis, and Combustion
82.
Pt2O
83.
Mg(ClO3)2
84.
P2O5
85.
SrO + H2O →
86.
BaCO3
87.
HNO3(aq)
88.
C4H10
89.
Al
90.
Cl2O3
91.
Al(OH)3
92.
iron(III) chlorate is heated
93.
zinc oxide powder is added to water
94.
pentane is ignited in air
95.
phosphorous acid is heated
96.
magnesium phosphide is exposed to an electric current
97.
lithium hydroxide is heated
98.
hydrogen gas is ignited in air
O2 →
+
+
O2
+
H2 O →
7
99.
magnesium ribbon is heated in the presence of sulfur
100.
scandium carbonate is heated
101.
dinitrogen pentoxide gas is bubbled through water
Single Replacement
102.
Zn
+
CuSO4 →
103.
Pb
+
Mg(NO3)2 →
104.
AgC2H3O2
105.
Cl2
106.
HF(aq)
107.
magnesium + nitric acid →
108.
sodium chloride + aluminum →
109.
barium + calcium sulfate →
110.
nickel(II) sulfate + lithium →
111.
potassium + water →
112.
silver + strontium chloride →
113.
sodium fluoride + iodine →
114.
rubidium + iron(III) sulfate →
115.
sodium + water →
+
+
Li →
KBr →
+
Ca →
8
116.
fluorine + aluminum bromide →
117.
phosphoric acid + calcium →
118.
copper + water →
Double Replacement
CaSO4 →
119.
AgCH3COO
120.
Pb(NO3)2
+
121.
AgNO3 +
FeCl3 →
122.
H2SO4
Ba(OH)2 →
123.
Al(OH)3 + NH4Cl
+
+
Na2S
→
→
124.
A solution of lead(II) chlorate is mixed with a solution of chromium(III) iodide.
125.
A solution of nitric acid is added to a solution of magnesium hydroxide.
126.
Solutions of copper(II) chloride and potassium carbonate are mixed.
127.
Solid sodium carbonate is sprinkled on a hydrochloric acid spill.
128.
Perchloric acid is neutralized by the addition of ammonium hydroxide.
Energy and Change of Enthalpy
129. Indicate the following as either exothermic or endothermic.
a) CH4 + 74.4 kJ → C + 2H2
a) ___________________
b) 1/8 S8 + O2 →
SO2
b) ___________________
C3H8 + 104 kJ
c) ___________________
→
d) ___________________
c) 3 C + 4 H2
→
d) butane + oxygen
e) CO2
→
CO + ½ O2
carbon dioxide + water
ΔH = +238kJ
e) ___________________
9
130. The energy term of an exothermic reaction is added to the (right / left) side of chemical
equation because energy is (absorbed / released).
131. The ∆H of an endothermic reaction is indicated as a (+ / −) value because the enthalpy
(potential energy) of the reactants is ( > / < ) than the enthalpy of the products.
132. All chemical fuels produce an (endothermic / exothermic) reaction upon ordinary combustion.
133. Baking a potato is an example of an (exothermic / endothermic ) reaction.
134. Copper and oxygen react according to the following:
Cu + ½ O2 → CuO ∆H = −155kJ
Rewrite this equation for 1 mole of O2 and include energy in the equation.
135. Carbon and sulfur react according to the following equation: 4C + S8 + 3511 kJ → 4CS2
Rewrite the equation for one mole of C, using the ∆H notation.
136. Draw an energy diagram for the equation given in the previous problem. Be sure to label all
parts. (progress of the reaction, enthalpy or energy, ∆H, reactants, and products.
137. Using the graph below, determine:
a. The activation energy needed for the forward reaction?___________________
b. The activation energy needed for the reverse reaction? ___________________
c. ∆H for the forward reaction? Endothermic or exothermic? ___________________
d. ∆H for the reverse reaction? Endothermic or exothermic? ___________________
e. Label the activated complex on the curve.
f. Sketch what the curve might look like if a catalyst was added.
10
138. Draw a potential energy diagram with the following criteria:
a. ∆Hrev = −30 kJ
b. Ea (forward reaction) = 70 kJ
c. Activated Complex = 90 kJ
139. Based on your diagram, determine:
a. ∆Hfor _____________________
c. Enthalpy of reactants__________________
b. Ea (reverse) _________________
d. Enthalpy of products_________________
Bond Energy
3
2
140. Given:
a. Identify the type and number of bonds broken in this reaction and determine the total
amount of energy required to break them.
b. Identify the type and number of bonds formed in this reaction and determine the total
amount of energy released when they are formed.
c. Calculate the enthalpy change for the entire reaction.
d. Is this reaction endothermic or exothermic?
e. Write a thermochemical equation for the reaction.
f. Draw and label a potential energy diagram for the reaction.
11
141. Using bond energies, calculate the enthalpy change for the following reactions:
2
a.
2
2
b.
2
c.
d.
3
2
2
6
12
Determining ∆H Using Hess’s Law: Each manipulated equation must be rewritten.
1) Given:
2P + 3Cl2 → 2PCl3
2P + 5Cl2 → 2PCl5
Calculate ΔH for:
PCl3 + Cl2 → PCl5
ΔH = −640. kJ
ΔH = −886 kJ
2) Given:
2HF → H2 + F2
2H2 + O2 → 2H2O
Calculate ΔH for:
2F2 + 2H2O → 4HF + O2
ΔH = +542.2 kJ
ΔH = −571.6 kJ
3) Given:
4NH3 + 5O2 → 4NO + 6H2O
4NH3 + 3O2 → 2N2 + 6H2O
Calculate ΔH for:
N2 + O2 → 2NO
ΔH = −1170 kJ
ΔH = −1530 kJ
4) Given:
4Al + 3O2 → 2Al2O3
4Fe + 3O2 → 2Fe2O3
Calculate ΔH for:
2Al + Fe2O3 → 2Fe + Al2O3
ΔH = −3351.4 kJ
ΔH = −1648.4 kJ
5) Given:
C + O2 → CO2
H2 + ½ O2 → H2O
2C2H2 + 5O2 → 4CO2 + 2H2O
Calculate ΔH for:
2C + H2 → C2H2
ΔH = −393.5 kJ
ΔH = −286 kJ
ΔH = −2598.8 kJ
13
Review (Identify reaction type before writing the equation)
142.
calcium metal is added to a solution of nitric acid.
143.
solutions of copper(II) nitrate and sodium hydroxide are mixed.
144.
scandium carbonate is heated
145.
nitrous acid is heated
146.
zinc + magnesium carbonate →
147.
dichlorine monoxide + water →
148.
calcium carbonate + perchloric acid →
149.
strontium chlorate is heated
150.
lead(IV) sulfide is exposed to an electric current
151.
the combustion of octane
152.
silver oxide + water →
153.
dichromic acid + ammonium hydroxide →
154.
barium metal is dropped in water
155.
copper(II) hydroxide is heated
156.
lithium + sulfur →
157.
bromine + iron(III) iodide →
158.
solutions of sodium phosphate and calcium bromide are mixed.
159.
barium metal is added to a solution of chlorous acid.
14
160.
chloric acid is heated
161.
aluminum metal is added to a solution of sodium chlorate
162.
dinitrogen pentoxide gas is bubbled through water
163.
lithium carbonate is heated
164.
ammonium carbonate powder is sprinkled on a hydrochloric acid spill
165.
iron(III) phosphide is exposed to an electric current
166.
hexane is ignited
167.
tin(II) oxide is added to water
168.
strontium hydroxide is combined with acetic acid
169.
tin(IV) hydroxide is heated
170.
a piece of silver metal is held in a Bunsen burner flame
171.
lead(II) sulfide is heated in a fluorine environment
172.
calcium hydroxide powder is added to an ammonium nitrate solution
173.
A hydrocarbon compound is found to be 85.71% carbon and 14.29% hydrogen by mass.
When vaporized at 35ºC, 0.136 g of the compound occupies a volume of 45.0 mL and exerts a
pressure of 691 torr. Write a balanced equation for the combustion of this compound.
15
174.
Given:
a. Write a balanced molecular equation in ΔH notation.
b. Is the reaction endothermic or exothermic?
c. Which has a higher enthalpy, the reactants or the products?
d. Would the temperature of the surroundings increase or decrease?
175.
Complete the following based on the reactions given below:
Reaction 1:
2MnO(s)  2Mn(s) + O2(g) H = +770.4 kJ/mol
Reaction 2:
2MnO(s) + O2(g)  2MnO2(s) H = −269.7 kJ/mol
a. Apply Hess’s Law to reactions 1 and 2 and determine the enthalpy change for the
following reaction:
Reaction 3:
Mn(s) + O2(g)  MnO2(s)
b.
Does reaction 3 release or absorb heat?
__________________
c. Is reaction 3 exothermic or endothermic?
__________________
d. Will reaction 3 cause an increase or decrease in temperature?
e. Write the thermochemical equation for reaction 3.
__________________
f. Write the equation for reaction 3 in H notation.
g. Draw and fully label an energy diagram for reaction 3.
16
Cumulative Review Questions
176.
For 2607000 give the following:
a)
Number written in scientific notation
_________________________
b)
Significant figures
_________________________
c)
Rounded to 3 significant figures
_________________________
177.
Convert 23.6 hectograms to milligrams
178.
A copper cube with a mass of 58.60 g is placed into a water-filled graduated
cylinder. The water in the cylinder rises from 26.5 mL to 33.1 mL. Determine the density
of the copper?
179.
List 3 physical properties and 3 chemical properties of water.
180.
Complete the following chart
Homogeneous or
Heterogeneous
Element, Compound,
Mixture, Solution
rubbing alcohol
calcium oxide
gasoline
181.
Write nuclear equations for:
a)
Alpha emission of radon-222
b)
Electron capture by nitrogen-15
c)
Neutron bombardment of oxygen-16
17
24
182.
What is the mass and charge of 5.26 x 10 electrons?
183.
A 2.65 gram sample of cobalt-55, with a half-life of 17.5 hours undergoes decay for 6.56
days. What mass of cobalt-55 remains at this point?
184.
An element consists of 1.40% of an isotope with mass 203.973 amu, 24.10% of an isotope
with mass 205.9745 amu, 22.10% of an isotope with mass 206.9759 amu, and 52.40% of
an isotope with mass 207.9766 amu. Calculate the average atomic mass and identify the
element.
185.
Where appropriate, write formulas or names for each of the following:
a. ammonium sulfate
___________
f) H3AsO4(aq)_________________________
b. dinitrogen monoxide ___________
g) FeSO3
_________________________
c. phosphorous acid
___________
h) CuSO4•5H2O ______________________
d. lead(IV) oxalate
___________
i) BF3
_________________________
e. aluminum nitrite
___________
j) Cr(OH)3
_________________________
186.
Determine the mass, in grams, of 4.22 x 1024 formula units of copper(I) sulfide.
187.
What is the total number of electrons in 0.915 moles of nitrogen atoms?