Chemistry 101

Determine the oxidation number of the elements in each of the following compounds:

a. H2CO3
H: +1, O: -2, C: +4

b. N2
N: 0

c. Zn(OH)42-
Zn: 2+, H: +1, O: -2

d. NO2-
N: +3, O: -2

e. LiH
Li: +1, H: -1

f. Fe3O4
Fe: +8/3, O: -2

Identify the species being oxidized and reduced in each of the following reactions:

a. 2 Cr+ + Sn4+ Cr3+ + Sn2+
Cr+: oxidized, Sn4+: reduced

b. 3 Hg2+ + 2 Fe (s) 3 Hg2 + 2 Fe3+
Hg2+: reduced, Fe: oxidized

c. 2 As (s) + 3 Cl2 (g) 2 AsCl3
As: oxidized, Cl2: reduced

Would you use an oxidizing agent or reducing agent in order for the following reactions to occur?

a. ClO3- ClO2 reducing agent

b. SO42- S2- reducing agent

c. Mn2+ MnO2 oxidizing agent

d. Zn ZnCl2 oxidizing agent

Write balanced equations for the following redox reactions:

a. 2 NaBr + Cl2 2 NaCl + Br2

b. Fe2O3 + 3 CO 2 Fe + 3 CO2 in acidic solution

c. 5 CO + I2O5 5 CO2 + I2 in basic solution

Write balanced equations for the following reactions:

a. Cr(OH)3 + Br2 CrO42- + Br- in basic solution

10 OH- + 2 Cr(OH)3 + 3 Br2 2 CrO42- + 8 H2O + 6 Br-

b. O2 + Sb H2O2 + SbO2- in basic solution

2 OH- + 2 Sb + 3 O2 + 2 H2O 2 SbO2- + 3 H2O2

c. HCOOH + MnO4- CO2 + Mn2+ in acidic solution

6 H+ + 2 MnO4- + 5 HCOOH 2 Mn2+ + 8 H2O + 5 CO2

d. ClO2- ClO2 + Cl- in acidic solution

5 ClO2- + 4 H+ 4 ClO2 + Cl- + 2 H2O

Write the balanced half reactions of the following reactions:

a. NiO2 + 2 H2O + Fe Ni(OH)2 + Fe(OH)2 in basic solution

2 H2O + NiO2 + 2 e- Ni(OH)2 + 2 OH-

2 OH- + Fe Fe(OH)2 + 2 e-

b. CO2 + 2 NH2OH CO + N2 + 3 H2O in basic solution

CO2 + H2O + 2 e- CO + 2 OH-

2 OH- + 2 NH2OH N2 + 2 e- + 4 H2O

c. 2 H+ + H2O2 + 2 Fe2+ 2 Fe3+ + 2 H2O in acidic solution

H2O2 + 2 e- + 2 H+ 2 H2 O

Fe2+ Fe3+ + e-

d. H+ + 2 H2O + 2 MnO4- + 5 SO2 2 Mn2+ + 5 HSO4- in acidic solution

8 H+ + 10 e- + 2 MnO4- 2 Mn2+ + 4 H2O

4 H2O + 5 SO2 5 HSO4- + 10 e- + 15 H+