Exercises
Exercise 1. Determine the oxidation number of nitrogen in the following compounds:
b) NO2 +4
c) N2O5 +5
d) N2O4 +4
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Exercise 2. Determine the oxidation number of bromine in the following compounds and ions.
b) HBrO2 +3
c) HBrO3 +5
d) HBrO4 +7
e) BrO4– +7
f) HBr -1
g) BrO2– +3
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Exercise 3. Answer the questions for the following reactions.
Here, we can write a net ionic equation because both Cu(NO3)2 and AgNO3 are soluble:
Cu (s) + 2 Ag+ (aq) → 2 Ag (s) + Cu2+ (aq)
What is the oxidation number of Ag (s)? 0
Which substance is oxidized? Cu (s)
Which substance is reduced? Ag+
b) Cl2 (aq) + 2 NaI (aq) → I2 (aq) + 2 NaCl (aq)
Here, we can write a net ionic equation because both NaI and NaCl are soluble:
Cl2 (aq) + I– (aq) → I2 (aq) + Cl– (aq)
Which substance is reduced? Cl2
Which substance is the oxidizing agent? I–
Which substance is the reducing agent? Cl2
c) CH3CH2OH (l) + 3 O2 (g) → 3 H2O (l) + 2 CO2 (g)
b) Which substance is the reducing agent? CH3CH2OH
c) Which substance is the oxidizing agent? O2
d) Which substance has been reduced? O2
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Exercise 4. Write a balanced equation for the reaction of solid magnesium with aqueous cobalt(II) sulfate to yield solid cobalt and aqueous magnesium sulfate. Indicate both the reducing agent and the oxidizing agent.
Mg (s) + CoSO4 (aq) → Co (s) + MgSO4 (aq)
The net ionic equation is:
Mg (s) + Co2+ → Co (s) + Mg2+ (aq)
Solid Mg is oxidized and Co2+ ion is reduced. The oxidizing agent is Co2+ ion and the reducing agent is solid Mg.