Name _____KEY_____________
Period ____
CRHS Academic Chemistry
UNIT 8 – Chemical Reactions
Practice Problems
Due Date
Assignment
On-Time (100)
Late (70)
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8.1
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8.2
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8.3
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8.4
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8.5
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Warm-Up
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EC
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Notes, Homework, Exam Reviews and Their KEYS located on CRHS
Academic Chemistry Website: https://cincochem.pbworks.com
Unit 8 HW
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Unit 8 HW
WARM-UPS
Day 1
Day 7
Day 2
Day 8
Day 3
Day 9
Day 4
Day 10
Day 5
Day 11
Day 6
Day 12
Unit 8 HW
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HW 8.1 REACTIONS AND SKELETAL EQUATIONS
1. List the 4 indicators of a chemical change.
a) ___Heat or cold________________________
b) ___gas____________________________
c) ___Precipitate________________________________
d) ___color change______________________________
2. Give the meaning of each symbol:
____yields or produces____
Δ
MnO2
(s) __solid including precipitate______
_exothermic (heat given off) _
(l) ___liquid_____
____MnO2 is catalyst________
(g) ____gas___________________
___reversible _______
(aq) ____a solution in water ________
3. Using the Law of Conservation of mass, solve for the missing values.
a. Fe2O5

304g
b. C7H16
Rb
+
224g
+
O2
_100_?
c. 2
Fe
_80_?

352g
+
Atoms Rb_2_
Atoms Br_2_
1
O2
CO2
+
308g
Br2



H2O
144g
2
RbBr
Atoms Rb_2_
Atoms Br_2__
4. Write the skeletal reaction from the following word reactions
a. Zinc metal reacts with silver nitrate powder to yield silver metal and zinc nitrate crystals
Zn(s) + AgNO3 (s)  Ag (s) + Zn (NO3)2 (s)
b. Solid lithium combines with solid sulfur to form lithium sulfide crystals
Li (s) + S (s)  Li2S (s)
c. Aqueous barium iodide is mixed with lithium phosphate to form aqueous lithium iodide and solid barium
phosphate
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Unit 8 HW
BaI2 (aq) + Li3PO4 (aq) __. LiI (aq) + Ba3(PO4)2 (s)
d. Solid manganese combines with bromine gas to form solid manganese (III) bromide
Mn (s) + Br2 (g)  MnBr3 (s)
e. Cobalt metal combines with sulfur powder to form cobalt (II) sulfide crystals
Mn (s) + Br2 (g)  MnBr3 (s)
f.
Cesium oxide crystals decompose into cesium metal and oxygen gas
Cs2O (s)  Cs (s) + O2 (g)
g. Potassium iodide crystals decompose into potassium metal and Iodine gas
Complete without Answer Key!
h. Solid aluminum combines with nitrogen gas to form aluminum nitride crystals
Complete without Answer Key!
i.
Solid sodium metal is placed in a flask with gaseous chlorine to form sodium chloride
Complete without Answer Key!
j.
Bromine gas is reacted with solid potassium iodide to form iodine gas and potassium bromide crystals
Complete without Answer Key!
Unit 8 HW
HW 8.2 BALANCING EQUATIONS
Balance the following chemical reactions.
1. __2_____H2 + _______O2  ___2___H2O
2. _______Mg + _______Cl2  _______MgCl2
3. __2__Ba + ______O2  ___2__BaO
4. __4__Al + ___3___O2  __2__Al2O3
5. __2___Mn2O7  ___4__Mn + ___7__O2
6. __3___H2 + _______N2  ___2__NH3
7. _4_Na + ___O2  _2_Na2O
8. _6__Mg + ___P4  _2_Mg3P2
9. ___K2O + ___H2O  _2_KOH
10. _2_Al + _3_CuO  ___Al2O3 + _3_Cu
11. ___SF6
 ___S + _3_ F2
12. _2_C5H12 + _11_O2  _10_CO + _12_H2O
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Unit 8 HW
Balance the following chemical reactions.
Complete remainder of HW 8.2 problems without access to KEY
1. ___F2 +___ Al2O3  ___AlF3 + ___O2
2. ___I2 + ___Na2S2O3  ___ NaI + ___Na2S4O6
3. ___ C2H6 +___ O2 ___ CO2 +___ H2O
4. ___ CaCl2 + ___AgNO3  ___ AgCl + ___Ca(NO3)2
5. ___ Al + ___CuSO4  ___Cu
6. ___C3H8
+ ___O2

+
___Al2(SO4)3
___CO2 + ___H2O
Unit 8 HW
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HW 8.3 DECOMPOSITION & SYNTHESIS REACTIONS
Are the following reactions synthesis or decomposition? Fill in the blank and balance.
1.
_2_NaCl(s)  _2_Na(s) + ___Cl2(g)
_____D_________
2.
_2_H2(g) + ___O2(g) 
_____S___________
3.
_2_BBr3
(s)
 _2_B
(s)+
_2_H2O(l)
_3_Br2
(g)
______D___________
Rewrite the following word equations as balanced chemical equations. Indicate synthesis or decomposition in
the blank.
4.
Solid lithium combines with solid sulfur to form lithium sulfide crystals
2 Li (s) + S (s)  Li2S (s)
__S____________________
Predict the products and balance the following reactions. Indicate synthesis or decomposition in the blank.
5.
___SF6
 S + 3 F2
6.
___Mg
+
7.
_2_Mn2O7
8.
_2_Ba
___Cl2  MgCl2
 4Mn + 7O2
+ ___O2  2 BaO
___D__________________
__S___________________
__D___________________
__S___________________
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Unit 8 HW
Complete remainder of HW 8.3problems without access to KEY
+ ___O2 
9.
___Al
10.
Solid strontium combines with bromine gas to form…
______________________
_____________________
11.
Cesium oxide crystals decompose into...
______________________
Unit 8 HW
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HW 8.4 COMBUSTION & SINGLE REPLACEMENT REACTIONS
Predict the products and balance the following combustion reactions.
1.
_2_C2H6(g)
2.
_2__Ca(s)
3.
_2_C6H14(g)
+
_7_O2(g)  4 CO2 + 6 H2O
___O2(g)  2 CaO
+
_19_O2(g)  12 CO2 + 14 H2O
+
Identify the following reactions as Synthesis, Decomposition, Combustion, or Single Replacement. There may
be more than one correct answer.
4.
Na + I2  NaI
5.
CH3OH + O2  CO2 + H2O
C
6.
MgO  Mg + O2
D
7.
F2 + CuBr2  Br2 + CuF2
SR
8.
Cobalt metal combines with sulfur powder to form cobalt (II) sulfide crystals
___S____
Co (s) + S (s) -> CoS (s)
____S________
9.
Potassium metal reacts with chromium (IV) nitrate to form potassium nitrate and chromium metal.
4 K (s) + Cr(NO3)4 (aq)  4 KNO3 (aq) + Cr (s)
____SR______________
Predict the products and balance the following single replacement reactions. Write “NR” if no reaction occurs.
10.
_2__K
+
___Zn(NO3)2  Zn + 2 KNO3
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Unit 8 HW
Complete remainder of HW 8.4 problems without access to KEY
11.
___FeCl3
+
___Mg 
12.
___Cl2
+
___AlBr3 
13.
___Na
+
___CaI2 
Identify, predict the products, and balance the following reactions.
14.
___NH3
15.
___Al

+
___Mg2P3 
Unit 8 HW
Page 12 of 16
HW 8.5 DOUBLE REPLACEMENT & ACID BASE REACTIONS
Identify the following reactions as Synthesis, Decomposition, Combustion, Single Replacement, Acid-Base, or
Precipitation. There may be more than one correct answer.
1.
Li2CO3 + BaBr2  LiBr + BaCO3
2.
Pentane (C5H12) burns with oxygen to form carbon dioxide and water.
DR
C5H12 + 8 O2  5 CO2 + 6 H2O
C
3.
F2 + Li  LiF
4.
Potassium iodide crystals are heated to form potassium metal and iodine gas
S
2 KI  2 K + I2
D
5.
HNO3 + Ba(OH)2  Ba(NO3)2 + H2O
6.
Bromine gas is reacted with solid potassium iodide to form iodine gas and potassium bromide
AB
Br2 (g) + 2 KI (s)  I2 (g) + 2 KBr (s)
SR
Predict the products and balance the following double replacement reactions. Write “NR” if no reaction
occurs.
7. _2__Na3PO4 + _3_MgCl2  6 NaCl (aq) + Mg3(PO4)2 (s)
8. _2__K3PO4 + _3_Sr(ClO4)2
 6 KClO4 (aq) + Sr3(PO4)2 (s)
9. ___PbSO4(aq) + ___(NH4)2S(aq)  PbS (s) + (NH4)2SO4 (aq)
10. ___Ca(OH)2 + ___(NH4)2S  CaS (aq) + NH4OH (aq)
11. ___BaCl2 + ___CuSO4  BaSO4 (s) + CuCl2
NR, None are insoluble
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Unit 8 HW
Identify, predict the products, and balance the following reactions. Write “NR” if no reaction occurs.
12. ___AgNO3(aq) + ___NaCl(aq)  AgCl (s) + NaNO3 (aq)
__DR-PPT___
13. _2__Rb(s) + ___Se  Rb2Se
_S____
14. Iron (III) oxide is broken down…
__D___
2 Fe2O3  2 Fe + 3O2
15. ___SnCl4(aq) + ___Cr(s) 
_____
Assume Cr will be Cr+4
Complete remainder of HW 8.5 problems without access to KEY
16. Cs + I2  CsI
17. CH3CH2CH2OH + O2 
18. MgO  Mg + O2
_____
Unit 8 HW
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Page 15 of 16
Unit 8 HW
20 Common Polyatomic Ions
Name
Ion
Name
Ion
acetate
C2H3O2–1 or CH3COO–1
hypochlorite
ClO–1
ammonium
NH4+1
nitrate
NO3–1
carbonate
CO3-2
nitrite
NO2–1
chlorate
ClO3–1
perchlorate
ClO4–1
chlorite
ClO2–1
permanganate
MnO4–1
chromate
CrO4-2
phosphate
PO4-3
cyanide
CN–1
phosphite
PO3-3
dichromate
Cr2O7-2
silicate
SiO3-2
hydrogen carbonate
HCO3–1
sulfate
SO4-2
hydroxide
OH–1
sulfite
SO3-2
Unit 8 HW
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