Introduction to Stoichiometry Review
1. Determine whether or not each of the following changes is a chemical reaction or
a physical reaction
a. Burning leaves
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b. Mowing the lawn
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c. Frying an egg
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d. Baking a cake
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e. Melting ice
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2. Translate the following into chemical formulae and balance the equation. Include
the phases when this information is given or known.
a. Copper + chlorine → Copper (I) chloride
b. Sodium oxide + water → Sodium hydroxide
c. Mercury (II) oxide → mercury + oxygen
d. Zinc carbonate → Zinc oxide + Carbon dioxide
e. Zinc + Sulfuric acid → Hydrogen + Zinc sulfate
f. Potassium + water → Potassium hydroxide + hydrogen
g.
Sodium sulfate + Barium chloride → Barium sulfate + Sodium chloride
h. Sulfuric acid + sodium acetate → Sodium sulfate + Acetic acid
i. The reaction of ammonia with iodine to form nitrogen triiodide (NI3) and
hydrogen gas.
j. The combustion of propane (C3H8).
k. The incomplete combustion of propane to form CO and water.
l. The reaction of nitric acid with potassium hydroxide.
m. The reaction of copper (II) oxide with hydrogen to form copper metal and
water.
n. The reaction of iron metal with oxygen to form iron (III) oxide.
o. The complete combustion of 2,2-dimethylpropane (C4H10) in oxygen.
p. The reaction of AlBr3 with Mg(OH)2
q. The decomposition of hydrogen peroxide to form water and oxygen.
r. Zinc and lead (II) nitrate react to form zinc nitrate and lead.
s. Aluminum bromide and chlorine gas react to form aluminum chloride and
bromine gas.
t. Sodium phosphate and calcium chloride react to form calcium phosphate
and sodium chloride.
u. Potassium metal and chlorine gas combine to form potassium chloride.
v. Aluminum and hydrochloric acid react to form aluminum chloride and
hydrogen gas.
w. Calcium hydroxide and phosphoric acid react to form calcium phosphate
and water.
x. Copper and sulfuric acid react to form copper (II) sulfate and water and
sulfur dioxide.
y. Hydrogen gas and nitrogen monoxide react to form water and nitrogen
gas.
3. For the following reactions, indicate whether the following are examples of
synthesis, decomposition, combustion, single displacement, double displacement,
or neutralization reactions:
a. Na3PO4 + 3 KOH → 3 NaOH + K3PO4
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b. MgCl2 + Li2CO3 → MgCO3 + 2 LiCl
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c. C6H12 + 9 O2 → 6 CO2 + 6 H2O
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d. Pb + FeSO4 → PbSO4 + Fe
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e. CaCO3 → CaO + CO2
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f. P4 + 3 O2 → 2 P2O3
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g. 2 RbNO3 + BeF2 → Be(NO3)2 + 2 RbF
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h. 2 AgNO3 + Cu → Cu(NO3)2 + 2 Ag
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i. C3H6O + 4 O2 → 3 CO2 + 3 H2O
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j. 2 C5H5 + Fe → Fe(C5H5)2
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k. SeCl6 + O2 → SeO2 + 3Cl2
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l. 2 MgI2 + Mn(SO3)2 → 2 MgSO3 + MnI4
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.
m. O3 → O + O2
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n. 2 NO2 → 2 O2 + N2
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4. For the following reactions, predict the products, balance, and indicate whether
the following are examples of synthesis, decomposition, combustion, single
displacement, double displacement, or neutralization reactions:
a. __ Na + __ FeBr3 →
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b. __ NaOH + __ H2SO4 →
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c. __ C2H4O2 +__ O2 →
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d. __ PbSO4 + __ AgNO3 →
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e. __ PBr3 →
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f. __ HBr + __ Fe →
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g. __ KMnO4 + __ ZnCl2 →
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h. __ MnO2 + __ Sn(OH)4 →
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i. __ O2 + __ C5H12O2 →
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j. __ H2O2 →
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5. Carbon reacts with oxygen according to this equation:
2 C(s) + O2(g) → 2 CO(g); ΔH = -220 kJ
Which statements are true?
1. The reaction is exothermic.
2. The system will absorb energy.
3. The beaker will feel warm.
6. When Na2S2O3 . 3 H2O(s) dissolves in water, the solution gets cold. Which energy
diagram best represents the behavior of this solution process?
7. A reaction has a positive ΔH value. What does this mean?
8. If you were given ΔH of a reaction, could you determine whether the reaction
was exothermic or endothermic? Explain.
9. Compare the enthalpy of the reactants and the products in both exothermic and
endothermic reactions.
Solutions:
1. a. chemical b. physical c. chemical d. chemical e. physical
2. a. 2 Cu + Cl2 → 2 CuCl b. Na2O + H2O → 2 NaOH c. 2 HgO → 2 Hg + O2
d. ZnCO3 → ZnO + CO2 e. Zn + H2SO4 → H2 + ZnSO4 f. 2 K + 2 H2O → 2 KOH + H2
g. Na2SO4 + BaCl2 → BaSO4 + 2 NaCl
h. H2SO4 + 2 NaCH3COO → Na2SO4 + 2 CH3COO i. 3 NH3 + 3 I2 → 2 NI3 + 3 H2
j. C3H8 + 5 O2 ← 3 CO2 + 4 H2O k.2 C3H8 + 7 O2 → 6 CO + 8 H2O
l. HNO3 + KOH → KNO3 + H2O m. CuO + H2 → Cu + H2O n. 4 Fe + 3 O2 → 2 Fe2O3
o. 2 C4H10 + 13 O2 → 8 CO2 + 10 H2O p. 2 AlBr3 + 3 Mg(OH)2 → 2 Al(OH)3 + 3 MgBr2
q. 2 H2O2 → 2 H2O + O2 r. 2 NH3 + H2SO4 → (NH4)2SO4
r. Zn + Pb(NO3)2 → Zn(NO3)2 + Pb s. 2 AlBr3 + 3 Cl2 → 2 AlCl3 + 3 Br2
t. 2 Na3PO4 + 3 CaCl2 6 NaCl + Ca3(PO4)2 u. 2 K + Cl2 → 2 KCl
v. 2 Al + 6 HCl → 3 H2 + 2 AlCl3 w. 3 Ca(OH)2 + 2 H3PO4 → Ca3(PO4)2 + 6 H2O
x. Cu + 2 H2SO4 → CuSO4 + 2 H2O + SO2 y. 2 H2 + 2 NO → 2 H2O + N2
3. a. DR b. DR c. C d. SR e. D f. S g. DR h. SR i. C j. S k. SR l. DR m. D n. D
4. a. 3 Na + 1 FeBr3 → 3 NaBr + 1 Fe; SR b. 2 NaOH + 1 H2SO4 →1 Na2SO4 + 2 H2O;
N c. 1 C2H4O2 + 2 O2 → 2 CO2 + 2 H2O; C
d. 1 PbSO4 + 2 AgNO3 → 1 Ag2SO4 + 1 Pb(NO3)2; DR e. 4 PBr3 → 1 P4 + 6 Br2; D
f. 6 HBr + 2 Fe → 3 H2 + 2 FeBr3; SR
g. 2 KMnO4 + 1 ZnCl2 → 2 KCl + 1 Zn(MnO4)2; DR
h. 1 MnO2 + 1 Sn(OH)4 → 1 Mn(OH)4 + 1 SnO2; DR
i. 7 O2 + 1 C5H12O2 → 5 CO2 + 6 H2O; C
j. 1 H2O2 → 1 H2 + 1 O2; D 5. 1 and 3 6. A 7. It’s endothermic. 8. – exothermic, +
endothermic 9. exothermic: enthalpy of products lower than the reactants; endothermic:
enthalpy of products higher than the reactants.