Complete and balance the reactions corresponding to the last digit of your Student ID Number.
0)
Cr(s) + HCl(aq) → Cr3+(aq) + H2(g) + Cl–(aq)
Mg(s) + O3(g) → Mg(OH)2(s) + O2(g)
1)
HI(aq) + ClO3–(aq) → I3–(aq) + Cl2(g)
Al(s) + ClO–(aq) → [Al(OH)4]–(aq) + Cl–(aq)
2)
As2O3(s) + NO2(g) → H3AsO4(aq) + NO(g)
Zn(s) + BrO–(aq) → [Zn(OH)4]2–(aq) + Br–(aq)
3)
HBr(aq) + MnO2(s) → Br2(l) + Mn2+(aq)
[Cr(OH)4]–(aq) + MnO4–(aq) → CrO42–(aq) + MnO2(s)
4)
H3AsO4(aq) + Al(s) → AsH3(g) + Al3+(aq)
Co(OH)2(s) + ClO2–(aq) → Co(OH)3(s) + ClO–(aq)
5)
HClO4(aq) + Fe2+(aq) → ClO3–(aq) + Fe3+(aq)
Ni(OH)3(s) + ClO2–(aq) → Ni(OH)2(s) + ClO3–(aq)
6)
H2SO3(aq) + Ag(s) + Br–(aq) → AgBr(s) + S(s)
Co(OH)3(s) + NO2–(aq) → Co(OH)2(s) + NO3–(aq)
7)
HNO3(aq) + Hg22+(aq) → Hg2+(aq) + NO(g)
AgO(s) + Zn(s) → Ag2O(s) + Zn(OH)2(s)
8)
NO2(g) + HCN(aq) → C2N2(g) + HNO2(aq)
Ag2O(s) + Al(s) → Ag(s) + Al(OH)3(s)
9)
H2S(aq) + BrO3–(aq) → BrO2(g) + S(s)
Mg(s) + ClO4–(aq) → Mg(OH)2(s) + ClO3–(aq)
0)
Cr(s) + HCl(aq) → Cr3+(aq) + H2(g) + Cl–(aq)
HCl(aq) indicates an acidic environment:
[ Cr(s) → Cr3+(aq) + 3 e– ] × 2 (oxidation)
[ 2 HCl(aq) + 2 e– → H2(g) + 2 Cl–(aq) ] × 3 (reduction)
Net: 2 Cr(s) + 6 HCl(aq) → 2 Cr3+(aq) + 3 H2(g) + 6 Cl–(aq)
Mg(s) + O3(g) → Mg(OH)2(s) + O2(g)
Mg(OH)2 indicates a basic environment:
Mg(s) + 2 H2O(l) → Mg(OH)2(s) + 2 H+(aq) + 2 e– (oxidation)
O3(g) + 2 H+(aq) + 2 e– → O2(g) + H2O(l) (reduction)
Net in acid: Mg(s) + O3(g) + H2O(l) → Mg(OH)2(s) + O2(g)
Neutralization: none
Net: Mg(s) + O3(g) + H2O(l) → Mg(OH)2(s) + O2(g)
1)
HI(aq) + ClO3–(aq) → I3–(aq) + Cl2(g)
HI indicates an acidic environment:
[ 3 HI(aq) → I3–(aq) + 3 H+(aq) + 2 e– ] × 5 (oxidation)
2 ClO3–(aq) + 12 H+(aq) + 10 e– → Cl2(g) + 6 H2O(l) (reduction)
Net: 15 HI(aq) + 2 ClO3–(aq) → 5 I3–(aq) + Cl2(g) + 3 H+(aq) + 6 H2O(l)
Al(s) + ClO–(aq) → [Al(OH)4]–(aq) + Cl–(aq)
[Al(OH)4]– indicates a basic environment:
[ Al(s) + 4 H2O(l) → [Al(OH)4]–(aq) + 4 H+(aq) + 3 e– ] × 2 (oxidation)
[ ClO–(aq) + 2 H+(aq) + 2 e– → Cl–(aq) + H2O(l) ] × 3 (reduction)
Net in acid: 2 Al(s) + 3 ClO–(aq) + 5 H2O(l) → 2 [Al(OH)4]–(aq) + 3 Cl–(aq) + 2 H+(aq)
Neutralization: 2 H+(aq) + 2 OH–(aq) → 2 H2O(l)
Net: 2 Al(s) + 3 ClO–(aq) + 2 OH–(aq) + 3 H2O(l) → 2 [Al(OH)4]–(aq) + 3 Cl–(aq)
2)
As2O3(s) + NO2(g) → H3AsO4(aq) + NO(g)
H3AsO4 indicates an acidic environment:
As2O3(s) + 5 H2O(l) → 2 H3AsO4(aq) + 4 H+(aq) + 4 e– (oxidation)
[ NO2(g) + 2 H+(aq) + 2 e– → NO(g) + H2O(l) ] × 2 (reduction)
Net: As2O3(s) + 2 NO2(g) + 3 H2O(l) → 2 H3AsO4(aq) + 2 NO(g)
Zn(s) + BrO–(aq) → [Zn(OH)4]2–(aq) + Br–(aq)
[Zn(OH)4]2– indicates a basic environment:
Zn(s) + 4 H2O(l) → [Zn(OH)4]2–(aq) + 4 H+(aq) + 2 e– (oxidation)
BrO–(aq) + 2 H+(aq) + 2 e– → Br–(aq) + H2O(l) (reduction)
Net in acid: Zn(s) + BrO–(aq) + 3 H2O(l) → [Zn(OH)4]2–(aq) + Br–(aq) + 2 H+(aq)
Neutralization: 2 H+(aq) + 2 OH–(aq) → 2 H2O(l)
Net: Zn(s) + BrO–(aq) + H2O(l) + 2 OH–(aq) → [Zn(OH)4]2–(aq) + Br–(aq)
3)
HBr(aq) + MnO2(s) → Br2(l) + Mn2+(aq)
HBr indicates an acidic environment:
2 HBr(aq) → Br2(l) + 2 H+(aq) + 2 e– (oxidation)
MnO2(s) + 4 H+(aq) + 2 e– → Mn2+(aq) + 2 H2O(l) (reduction)
Net: 2 HBr(aq) + MnO2(s) + 2 H+(aq) → Br2(l) + Mn2+(aq) + 2 H2O(l)
[Cr(OH)4]–(aq) + MnO4–(aq) → CrO42–(aq) + MnO2(s)
[Cr(OH)4]– indicates a basic environment:
[Cr(OH)4]–(aq) → CrO42–(aq) + 4 H+(aq) + 3 e– (oxidation)
MnO4–(aq) + 4 H+(aq) + 3 e– → MnO2(s) + 2 H2O(l) (reduction)
Net in acid: [Cr(OH)4]–(aq) + MnO4–(aq) → CrO42–(aq) + MnO2(s) + 2 H2O(l)
Neutralization: none
Net: [Cr(OH)4]–(aq) + MnO4–(aq) → CrO42–(aq) + MnO2(s) + 2 H2O(l)
4)
H3AsO4(aq) + Al(s) → AsH3(g) + Al3+(aq)
H3AsO4 indicates an acidic environment:
[ H3AsO4(aq) + 8 H+(aq) + 8 e– → AsH3(g) + 4 H2O(l) ] × 3 (reduction)
[ Al(s) → Al3+(aq) + 3 e– ] × 8 (oxidation)
Net: 3 H3AsO4(aq) + 8 Al(s) + 24 H+(aq) → 3 AsH3(g) + 8 Al3+(aq) + 12 H2O(l)
Co(OH)2(s) + ClO2–(aq) → Co(OH)3(s) + ClO–(aq)
Co(OH)2 and Co(OH)3 indicate a basic environment:
[ Co(OH)2(s) + H2O(l) → Co(OH)3(s) + H+(aq) + e– ] × 2 (oxidation)
ClO2–(aq) + 2 H+(aq) + 2 e– → ClO–(aq) + H2O(l) (reduction)
Net in acid: 2 Co(OH)2(s) + ClO2–(aq) + H2O(l) → 2 Co(OH)3(s) + ClO–(aq)
Neutralization: none
Net: 2 Co(OH)2(s) + ClO2–(aq) + H2O(l) → 2 Co(OH)3(s) + ClO–(aq)
5)
HClO4(aq) + Fe2+(aq) → ClO3–(aq) + Fe3+(aq)
HClO4 indicates an acidic environment:
HClO4(aq) + H+(aq) + 2 e– → ClO3–(aq) + H2O(l) (reduction)
[ Fe2+(aq) → Fe3+(aq) + e– ] × 2 (oxidation)
Net: HClO4(aq) + 2 Fe2+(aq) + H+(aq) → ClO3–(aq) + 2 Fe3+(aq) + H2O(l)
Ni(OH)3(s) + ClO2–(aq) → Ni(OH)2(s) + ClO3–(aq)
Ni(OH)3 and Ni(OH)2 indicate a basic environment:
[ Ni(OH)3(s) + H+(aq) + e– → Ni(OH)2(s) + H2O(l) ] × 2 (reduction)
ClO2–(aq) + H2O(l) → ClO3–(aq) + 2 H+(aq) + 2 e– (oxidation)
Net in acid: 2 Ni(OH)3(s) + ClO2–(aq) → 2 Ni(OH)2(s) + ClO3–(aq) + H2O(l)
Neutralization: none
Net: 2 Ni(OH)3(s) + ClO2–(aq) → 2 Ni(OH)2(s) + ClO3–(aq) + H2O(l)
6)
H2SO3(aq) + Ag(s) + Br–(aq) → AgBr(s) + S(s)
H2SO3 indicates an acidic environment:
H2SO3(aq) + 4 H+(aq) + 4 e– → S(s) + 3 H2O(l) (reduction)
[ Ag(s) + Br–(aq) → AgBr(s) + e– ] × 4 (oxidation)
Net: H2SO3(aq) + 4 Ag(s) + 4 Br–(aq) + 4 H+(aq) → 4 AgBr(s) + S(s) + 3 H2O(l)
Co(OH)3(s) + NO2–(aq) → Co(OH)2(s) + NO3–(aq)
Co(OH)3 and Co(OH)2 indicate a basic environment:
[ Co(OH)3(s) + H+(aq) + e– → Co(OH)2(s) + H2O(l) ] × 2 (reduction)
NO2–(aq) + H2O(l) → NO3–(aq) + 2 H+(aq) + 2 e– (oxidation)
Net in acid: 2 Co(OH)3(s) + NO2–(aq) → 2 Co(OH)2(s) + NO3–(aq) + H2O(l)
Neutralization: none
Net: 2 Co(OH)3(s) + NO2–(aq) → 2 Co(OH)2(s) + NO3–(aq) + H2O(l)
7)
HNO3(aq) + Hg22+(aq) → Hg2+(aq) + NO(g)
HNO3 indicates an acidic environment:
[ HNO3(aq) + 3 H+(aq) + 3 e– → NO(g) + 2 H2O(l) ] × 2 (reduction)
[ Hg22+(aq) → 2 Hg2+(aq) + 2 e– ] × 3 (oxidation)
Net: 2 HNO3(aq) + 3 Hg22+(aq) + 6 H+(aq) → 6 Hg2+(aq) + 2 NO(g) + 4 H2O(l)
AgO(s) + Zn(s) → Ag2O(s) + Zn(OH)2(s)
Zn(OH)2 indicates a basic environment:
2 AgO(s) + 2 H+(aq) + 2 e– → Ag2O(s) + H2O(l) (reduction)
Zn(s) + 2 H2O(l) → Zn(OH)2(s) + 2 H+(aq) + 2 e– (oxidation)
Net in acid: 2 AgO(s) + Zn(s) + H2O(l) → Ag2O(s) + Zn(OH)2(s)
Neutralization: none
Net: 2 AgO(s) + Zn(s) + H2O(l) → Ag2O(s) + Zn(OH)2(s)
8)
NO2(g) + HCN(aq) → C2N2(g) + HNO2(aq)
HCN and HNO2 indicate an acidic environment:
[ NO2(g) + H+(aq) + e– → HNO2(aq) ] × 2 (reduction)
2 HCN(aq) → C2N2(g) + 2 H+(aq) + 2 e– (oxidation)
Net: 2 NO2(g) + 2 HCN(aq) → C2N2(g) + 2 HNO2(aq)
Ag2O(s) + Al(s) → Ag(s) + Al(OH)3(s)
Al(OH)3 indicates a basic environment:
[ Ag2O(s) + 2 H+(aq) + 2 e– → 2 Ag(s) + H2O(l) ] × 3 (reduction)
[ Al(s) + 3 H2O(l) → Al(OH)3(s) + 3 H+(aq) + 3 e– ] × 2 (oxidation)
Net in acid: 3 Ag2O(s) + 2 Al(s) + 3 H2O(l) → 6 Ag(s) + 2 Al(OH)3(s)
Neutralization: none
Net: 3 Ag2O(s) + 2 Al(s) + 3 H2O(l) → 6 Ag(s) + 2 Al(OH)3(s)
9)
H2S(aq) + BrO3–(aq) → BrO2(g) + S(s)
H2S indicates an acidic environment:
H2S(aq) → S(s) + 2 H+(aq) + 2 e– (oxidation)
[ BrO3–(aq) + 2 H+(aq) + e– → BrO2(g) + H2O(l) ] × 2 (reduction)
Net: H2S(aq) + 2 BrO3–(aq) + 2 H+(aq) → 2 BrO2(g) + S(s) + 2 H2O(l)
Mg(s) + ClO4–(aq) → Mg(OH)2(s) + ClO3–(aq)
Mg(OH)2 indicates a basic environment:
Mg(s) + 2 H2O(l) → Mg(OH)2(s) + 2 H+(aq) + 2 e– (oxidation)
ClO4–(aq) + 2 H+(aq) + 2 e– → ClO3–(aq) + H2O(l) (reduction)
Net in acid: Mg(s) + ClO4–(aq) + H2O(l) → Mg(OH)2(s) + ClO3–(aq)
Neutralization: none
Net: Mg(s) + ClO4–(aq) + H2O(l) → Mg(OH)2(s) + ClO3–(aq)