For the following six reactions, identify the oxidation numbers of the elements in the elements and
compounds involved.
From this, determine which equations are examples of redox reactions and which are not.
1. NaCl (aq) + AgNO3 (aq) → AgCl (s) + NaNO3 (aq)
LHS :OS RHS: OS
Na= +1 Na = +1
Cl= -1 Cl = -1
Ag= +1 Ag =+1
N=+5 N =+5
O=-2 O =-2
No change = not a redox reaction .
2. H2 (aq) + F2 (aq) → 2HF (aq)
LHS :OS RHS: OS
H= 0 H = +1
F= 0 F = -1
This is a redox reaction:
H = oxidizing ( oxidisation occurring)
F = reducing (reduction occurring)
3. PCl5 (aq) + 4H2O (l) → H3PO4 (aq) + 5HCl (aq)
LHS :OS RHS: OS
P = +5 P = +5
Cl= -1 Cl= -1
H = +1 H = +1
O = -2 O = -2
No change = this is not a redox reaction.
4. Zn (s) + 2HCl (aq) → ZnCl2 (aq) + 2H2 (g)
LHS :OS RHS: OS
Zn = 0 Zn = +2
H = +1 H =0
Cl = -1 Cl = -1
This is a redox reaction:
Zn = oxidizing ( oxidisation occurring )
H = reduction ( reduction occurring )
5. Ca(OH)2 (aq) + 2HCl (aq) → CaCl2 (aq) + 2H2O (l)
LHS :OS RHS: OS
Ca = +2 Ca = +2
O = -2 O = -2
H = +1 H = +1
Cl = -1 Cl = -1
No change = this is not a redox reaction.
6. 3CuS (s) + 8HNO3 (aq) → 3CuSO4 (aq) + 8NO (g) + 4H2O (l)
LHS :OS RHS: OS
Cu = +2 Cu = +2
S = -2 S = +6
H = +1 H = +1
BTEC Applied Science Level 3 / Unit 13 Assignment 2 / Answered by Moreen Mero
,N = +5 N = +2
O = -2 O = -2
This is a redox reaction:
S = oxidizing ( oxidisation occurring )
N = reducing (reduction occurring )
7. KMnO4 (aq) + 6H2SO4 (aq) → 2K2SO4 (aq) + 4MnSO4 (aq) + 6H2O (l) + 5O2 (g)
LHS :OS RHS: OS
K = +1 K = +1
Mn = +7 Mn = +2
O = -2 O = -2
H = +1 H = +1
S = +6 S = +6
This is a redox reaction:
Mn = reducing ( reduction occurring )
O = oxidizing ( oxidisation occurring )
Balance the following redox equations, by identifying and using the oxidation numbers within each species
and the numbers of electrons lost or gained.
Cell Voltage Calculation:
Eocell = Eoreduction + E°oxidation
= 0.76 – 0.13 = 0.43 V
o Pb(s) | Pb2+(aq) ¦¦ Cu2+(aq) | Cu(s)
Oxidation half equation: Pb(s) → Pb2+(aq) + 2e-
Reduction half equation: Cu2+(aq) + 2e- → Cu(s)
Full redox equation: Pb(s) + Cu2+(aq) → Pb2+(aq) + Cu (s)
Cell Voltage Calculation:
Eocell = Eoreduction + E°oxidation
= 0.13 + 0.34 = 0.47 V
BTEC Applied Science Level 3 / Unit 13 Assignment 2 / Answered by Moreen Mero
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