Spontaneous Redox Reactions
Description: One of many examples of spontaneous redox reactions is when zinc metal is placed in a solution of copper sulfate, the copper is reduced and appears as a black coating on the zinc. Other examples of redox reactions include:
SnCl2(HCl) + 2Ce(SO4)2(HCl) → Sn(IV) + 2Ce(III) + 2Cl–(aq) + 4SO4-2(aq) yellow to clear
5SnCl2(HCl) + 2KMnO4(HCl) + 12H+ → 5Sn(IV) + 2Mn(II) + 2K+(aq) + 10Cl–(aq) + 6H2O(l) purple to clear pink
10KI(aq) + 2KMnO4(HCl) + 16H+(aq) → 5I2(aq) + 2Mn(II) + 8H2O(l) purple to brown
3SnCl2(HCl) + K2Cr2O7(aq) + 14H+(aq) → 3Sn(IV) + 2Cr(III) + 7H2O(l) orange to blue
5H2O2(aq) + 2KMnO4(HCl) + 6H+(aq) → 8H2O(l) + 5O2(g) + 2Mn(II) purple to clear with gas
NH4OH(aq) + KMnO4(aq) + ∆ → MnO2(s) + NO3-(aq) + K+(aq) purple to dark green
2KI(aq) + HCl + H2O2(aq) → I2(aq) + 2H2O(l) clear to brown
Cu(s) + 2AgNO3(aq) + 2H+(aq) → Cu(NO3)2(aq) + 2Ag+(aq) + H2O(l) clear to blue
Cu(s) + 2HNO3(conc) → Cu(NO2)2(s) + 2NO2(g) clear to green to blue with brown gas
Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s) blue to clear with solid
Source: UW Card Catalog
Year: N/A Vol: N/A Page: N/A
Keywords: Redox, Zinc, Copper Sulfate, Spontaneous
Rating: 
Hazard: Medium
- Acute toxicity hazard – oral
- Aquatic toxicity hazard
- Corrosive to metals
- Oxidizer
- Serious eye damage
Effectiveness: Good
- Results are observable with guidance
- Good connection from demo to course material
- Mild effects are seen by audience
- High reliability
- Time to results is medium
Difficulty: Low
- Use of reagents
- Simple manipulations for most to perform
- Simple procedures
Safety Precautions:
- Eye protection required
- Gloves required
- Absorbent materials on hand
- Avoid exposure to droplets, mists, or vapors
- Prevent release of reagents to the environment
Class: Redox Reactions, Thermodynamics, Electrochemistry
Division: General
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