Post on 15-Jul-2015
http://lawrencekok.blogspot.com
Prepared by Lawrence Kok
Tutorial on Redox, Reactivity Series and Displacement reactions.
Reactivity Series
• Metal arranged according to their ability to lose electron - form +ve ions• Measure tendency of metals in losing electrons (Undergo oxidation)• Metals – lose electrons – form electropositive ions – Oxidation Process
Reactivity series Metals with water, acids, oxygen
Reactivity seriesNon metal, Hydrogen and Carbon
Displacement rxn (H atom from H2O/HCI)Reactive metal displace H atom from water 2K + 2H2O → 2KOH + H2
Ca + 2H2O → Ca(OH)2 + H2
Less reactive metal displace H atom from acidMg + 2HCI → MgCI2 + H2
Zn + H2SO4 → ZnSO4 + H2
Unreactive metal – No rxn with water/acidAu + HCI →
Displacement rxn (REDOX rxn)-reactive metal displace less reactive metal from its sol
Reducing agent ↓ Oxidation
Oxidizing agent ↓ Reduction
2K + 2H2O 2KOH + H→ 2
(0) K oxi – ON ↑ (+1)
(+1) H red – ON ↓ (0)
Reducing agent ↓ Oxidation
Oxidizing agent ↓ Reduction
(0) Mg oxi – ON ↑ (+2)
(+1) H red – ON ↓ (0)
Reactivity seriesNon metal, Hydrogen and Carbon
Mg + 2HCI MgCI→ 2 + H2
Displacement rxn (O atom from less reactive)Reactive metal displace O from less reactive metal2Al + Fe2O3 → Al2O3 + 2Fe Zn + PbO → ZnO + Pb
Displacement rxn (O atom from less reactive)Reactive non metal displace O from less reactive metal3C + 2Fe2O3→ 3CO2 + 4FeH2 + CuO→ H2O + Cu
Displacement rxn (less reactive ions)Reactive metal displace less reactive ions from its salt Zn + CuSO4 → ZnSO4 + Cu2Al + 3CuCI2 → 2AlCI3 + 3Cu
Reactive metals Strong reducing agent
Reducing agent ↓ Oxidation
(0) Ai oxi – ON ↑ (+3)
2Al + 2Fe2O3 AI→ 2O3 + 2Fe
(+3) Fe red – ON ↓ (0)
Oxidizing agent ↓ Reduction
Zn + CuSO4 ZnSO→ 4 + Cu
Reducing agent ↓ Oxidation
Oxidizing agent ↓ Reduction
(0) Zn oxi – ON ↑ (+2)
(+2) Cu red – ON ↓ (0)
Reactivity Series
Reactivity series Metals with water, acids, oxygen
Reactivity seriesNon metal, Hydrogen and Carbon
Displacement rxn (H atom from H2O/HCI)Reactive metal displace H atom from water 2K + 2H2O → 2KOH + H2
Ca + 2H2O → Ca(OH)2 + H2
Less reactive metal displace H atom from acidMg + 2HCI → MgCI2 + H2
Zn + H2SO4 → ZnSO4 + H2
Unreactive metal – No rxn with water /acidAu + HCI →
Displacement rxn (REDOX reaction)-reactive metal displace less reactive metal from its sol
Reactivity seriesNon metal, Hydrogen and Carbon
Displacement rxn (O atom from less reactive)Reactive metal displace O from less reactive metal2Al + Fe2O3 → Al2O3 + 2FeZn + PbO → ZnO + Pb
Displacement rxn (O atom from less reactive)Reactive non metal displace O from less reactive metalC + 2Fe2O3→ 3CO2 + 4FeH2 + CuO→ H2O + Cu
Displacement rxn (less reactive ions)Reactive metal displace less reactive ions from its salt Zn + CuSO4 → ZnSO4 + Cu2Al + 3CuCI2 → 2AlCI3 + 3Cu
Reactive metals Strong reducing agent
Click here AI/CuCI3 displacement
Click here to view Flinn Scientific
Click here Iron extraction (Thermite)
• Metal arranged according to their ability to lose electron - form +ve ions• Measure tendency of metals in losing electrons (Undergo oxidation)• Metals – lose electrons – form electropositive ions – Oxidation Process
Click here microscale Fe reduction
Reactivity Series
• Metals arranged according to their ability to lose electron - form +ve ions• Measure tendency of metals in losing electrons (Undergo oxidation)• Metals – lose electrons – form electropositive ions – Oxidation Process
Reactivity seriesNon metal, Hydrogen and Carbon
Reactive metals Strong reducing agent
reactivity increase
Strong reducing
agent
Oxidation rxn favour
stro
ng
red
uc
ing
ag
ent
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red
uc
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ag
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Reactivity seriesNon metal, Halogen (Gp 7)
Metal → lose elec (Oxidation) M → M+ +
Non Metal + gain elec → (Reduction)
F + → F-
stro
ng
oxi
diz
ing
ag
ent
reactivity increase
Strong oxidizing
agent
Reduction rxn favour
MgAIZnFePbCuAg
Strongest reducing agent.Oxidized easily (lose e)
Weakest reducing agent.Least readily oxidized
FCIBr I
Metals
Non Metals Halogens
Strongest oxidizing agent.Reduced easily (gain e)
Weakest oxidizing agent.Least readily reduced
Reactivity Series
• Metals arranged according to their ability to lose electron - form +ve ions• Measure tendency of metals in losing electrons (Undergo oxidation)• Metals – lose electrons – form electropositive ions – Oxidation Process
Reactive metals Strong reducing agent
K ↔ K+ + eNa ↔ Na+ + eCa ↔ Ca2+ + 2e
Mg ↔ Mg2+ + 2e
Al ↔ Al3+ + 3e
Zn ↔ Zn2+ + 2e
Sn ↔ Sn2+ + 2e
Pb ↔ Pb2+ + 2e
Cu ↔ Cu2+ + 2e
Ag ↔ Ag+ + eAu ↔ Au+ + e
Potassium metal, K• Strong Reducing Agent• High Tendency lose e↑
Gold metal Au • Weak Reducing Agent• Low ↓ Tendency to lose e
Potassium ion K+
• Weak Oxidising Agent• Low ↓ Tendency gain e
Gold ion Au+ • Strong Oxidising Agent• High Tendency gain e↑
Strong Reducing Agent
Strong Oxidising Agent
Displacement rxn (REDOX rxn)-Reactive metal displace less reactive metal from its sol
• Add Zn, Mg, Cu, Pb into spotting tile• Make observation if rxn happen• Reactive metal displace less reactive metal from it solution• Arrange metal in order of reactivity
Mg Zn Pb Cu
Magnesiumnitrate
Zincnitrate
Lead nitrate
Coppernitrate
Click here displacement expt
Solution/Metal
Mg Zn Pb Cu
Magnesium nitrate
Zinc nitrate
Lead nitrate
Copper nitrate
Result
Zn → Zn 2+ + 2e (oxidized)Cu2+ + 2e → Cu (reduced)
Zn displaces Cu from its sol
Zn + CuSO4 ZnSO→ 4 + Cu
Click here redox practical filter paper
Oxidation ability – Losing electron - +ve ions
K Na Ca Mg AI C Zn H Fe Sn Pb
Cu Ag
Reactivity Series
• Metal arranged according to their ability to lose electron - form +ve ions• Measure tendency of metals in losing electrons (Undergo oxidation)• Metal – lose electrons – form electropositive ions – Oxidation Process
Reactive metals Strong reducing agent
Displacement rxn (REDOX rxn)-Reactive metal displace less reactive metal from its sol
• Add Zn, Mg, Cu, Pb into spotting tile• Make observation if rxn happen• Reactive metal displace less reactive metal from it solution• Arrange metal in order of reactivity
Mg Zn Pb Cu
Magnesium nitrate
Zincnitrate
Lead nitrate
Coppernitrate
Click here displacement expt
Solution/Metal
Mg Zn Pb Cu
Magnesium nitrate
Zinc nitrate
Lead nitrate
Copper nitrate
Result
Zn → Zn 2+ + 2e (oxidized)Cu2+ + 2e → Cu (reduced)
Zn displaces Cu from its sol
Zn + Cu(NO3)2 Zn(NO→ 3)2 + Cu
Most reactive
Least reactive
Zn more reactive
О
О
Cu less reactive
Add Zn into copper nitrateDisplacement rxn – Brown Cu ppt depositedBlue sol fades away (Cu2+ conc decrease)
Reducing agent ↓ Oxidation
Oxidizing agent ↓ Reduction
(0) Zn oxi – ON ↑ (+2)
(+2) Cu red – ON ↓ (0)
Observation
Zn + CuSO4 ZnSO→ 4 + Cu
Mg > Zn > Pb > Cu
K Na Ca Mg AI C Zn H Fe Sn Pb
Cu Ag
Reactivity Series
• Metal arranged according to their ability to lose electron - form +ve ions• Measure tendency of metals in losing electrons (Undergo oxidation)• Metal – lose electrons – form electropositive ions – Oxidation Process
Reactive metals Strong reducing agent
Displacement rxn (REDOX rxn)-Reactive metal displace less reactive metal from its sol
• Add Mg, Zn, Pb, Cu to spotting tile with AgNO3
• Make observation if rxn happen• Reactive metal displace less reactive metal from it solution• Arrange metal in order of reactivity
Silver nitrate
Click here displacement expt
Metal/Solution
Mg Zn Pb Cu
Silver nitrate
Result
Cu → Cu2+ + 2e (oxidized)Ag+ + e → Ag (reduced)
Cu displaces Ag+ from its sol
Cu + AgNO3 Cu(NO→ 3)2 + Ag
Less reactive
ОО
Cu more reactive
Add Cu into silver nitrateDisplacement rxn – Grey Ag ppt depositedBlue sol forms (Cu2+ conc increases)
Reducing agent ↓ Oxidation
Oxidizing agent ↓ Reduction
(0) Cu oxi – ON ↑ (+2)
(+1) Ag red – ON ↓ (0)
Observation
Cu + AgNO3 Cu(NO→ 3)2 + Ag
Mg > Zn > Pb > Cu > Ag
Mg Zn Pb Cu
Click here Cu/AgNO3 displacement
Metal/Solution
Mg Zn Fe Cu
Hydrochloric acid (HCI)
K Na Ca Mg AI C Zn H Fe Sn Pb
Cu Ag
Reactivity Series
• Metal arranged according to their ability to lose electron - form +ve ions• Measure tendency of metals in losing electrons (Undergo oxidation)• Metal – lose electrons – form electropositive ions – Oxidation Process
Reactive metals Strong reducing agent
Displacement rxn (REDOX rxn)-Reactive metal displace less reactive metal from its sol
• Add Mg, Zn, Fe, Cu to spotting tile with HCI• Make observation if rxn happen• Reactive metal displace less reactive metal from it solution• Arrange metal in order of reactivity
HCI
Click here displacement expt
Result
Zn → Zn2+ + 2e (oxidized)2H+ + 2e → H2 (reduced)
Zn displaces H+ from its sol
Zn + 2HCI ZnCI→ 2 + H2
Less reactive
ОО
Zn more reactive Add Zn into Hydrochloric acidDisplacement rxn – Effervescence H2 gas seen
Reducing agent ↓ Oxidation
Oxidizing agent ↓ Reduction
(0) Zn oxi – ON ↑ (+2)
(+1) H red – ON ↓ (0)
Observation
Zn + HCI ZnCI→ 2 + H2
Mg > Zn > H > Fe > Cu
Mg Zn Fe Cu
H2 production
Metal above Zn able to displace H from acid – H2 gasО
K Na Ca Mg AI C Zn H Fe Sn Sn
Pb Cu
AgО
Metal oside MgO ZnO Fe2O3 CuO
Carbon
Reactivity Series
• Metal arranged according to their ability to lose electron - form +ve ions• Measure tendency of metals in losing electrons (Undergo oxidation)• Metal – lose electrons – form electropositive ions – Oxidation Process
Reactive metals Strong reducing agent
Displacement rxn (REDOX rxn)-Reactive metal displace less reactive metal from its oxide/ores
• Add Metal oxide into crucible with Carbon• Make observation if rxn happen• Reactive metal displace less reactive metal from it ores• Arrange metal in order of reactivity
C
Click here displacement expt
Result
C → C2+ + 2e (oxidized)Fe3+ + 3e → Fe (reduced)
C displace Fe3+ from its oxide
3C + Fe2O3 3CO→ + 2Fe
Less reactive
О
C more reactive
Add Carbon into iron oxide, Fe2O3
Displacement rxn – Effervescence CO gas seenBrown iron produced
Reducing agent ↓ Oxidation
Oxidizing agent ↓ Reduction
(0) C oxi – ON ↑ (+2)
(+3) Fe red – ON ↓ (0)
Observation
Mg > C > Zn > Fe > Cu
MgO ZnO Fe2O3 CuO
Iron extraction
3C + Fe2O3 3CO→ + 2Fe
Metal above Pb able to displace Fe from its oxide
О
Metal oxide C AI
Fe2O3
K Na Ca Mg AI C Zn H Fe Sn Pb
Cu Ag
Reactivity Series
• Metal arranged according to their ability to lose electron - form +ve ions• Measure tendency of metals in losing electrons (Undergo oxidation)• Metal – lose electrons – form electropositive ions – Oxidation Process
Reactive metals Strong reducing agent
Displacement rxn (REDOX rxn)-Reactive metal displace less reactive metal from its oxide/ores
• Add carbon and aluminium to crucible with Fe2O3
• Make observation if rxn happen• Reactive metal displace less reactive metal from it ores• Arrange metal in order of reactivity
Result
C → C2+ + 2e (oxidized)Fe3+ + 3e → Fe (reduced)
C displace Fe3+ from its oxide
3C + Fe2O3 3CO→ + 2Fe
Less reactive
О
О
AI/C more reactiveAdd Carbon/Aluminium to iron oxide, Fe2O3
Displacement rxn – Effervescence seen CO gas producedBrown iron produced
Reducing agent ↓ Oxidation
Oxidizing agent ↓ Reduction
(0) C oxi – ON ↑ (+2)
(+3) Fe red – ON ↓ (0)
Observation
AI > C > Fe
Iron extraction
3C + Fe2O3 3CO→ + 2Fe
Metal above Pb able to displace Fe from its oxide
2AI + Fe2O3 AI→ 2O3 + 2Fe
Thermite welding
AI → AI3+ + 3e (oxidized)Fe3+ + 3e → Fe (reduced)
Al displace Fe3+ from its oxide
О
(0) AI oxi – ON ↑ (+3)
(+3) Fe red – ON ↓ (0)
Reducing agent ↓ Oxidation
Oxidizing agent ↓ Reduction
2AI + Fe2O3 AI→ 2O3 + 2Fe
F
CI
Br
I
Reactivity Series
• Non metal arranged according to their ability to gain electron - form -ve ion• Measure tendency of non metal in gaining electron (Undergo reduction)• Non Metal – gain electron – form electronegative ion – Reduction Process
Reactive non metals (Halogens, Gp 7) Strong oxidizing agent
Displacement rxn (REDOX rxn)-Reactive halogen displace less reactive halide from its solution
• Add CI2, Br2, I2 into tubes .• Make observation if rxn happen• Reactive halogen displace less reactive halogen from its solution• Arrange halogen in order of reactivity
Result
2Br- → Br2 + 2e (oxidized)
CI + e → CI- (reduced)CI displace Br- from its solution
CI2 + 2NaBr 2NaCI→ + Br2
Br less reactiveОО
CI more reactive
Add CI2 into NaBrDisplacement rxn – reddish brown solution
Reducing agent ↓ Oxidation
Oxidizing agent ↓ Reduction
(-1) Br oxi – ON ↑ (0)
(0) CI red – ON ↓ (-1)
Observation
F > CI > Br > I
О
Halogen/Halide
CI2 Br2 I2
Sodium chloride
Sodium bromide
Sodium iodide Click here video displacement rxn
CI2 + 2NaBr -> 2NaCI + Br2 ✓
CI2 + 2NaI -> 2NaCI + I2 ✓Br2 + NaCI -> ✗Br2 + 2NaI -> 2NaBr + I2 ✓I2 + NaCI -> ✗I2 + NaBr -> ✗
Reactive halogen displace less reactive halogen from its halide solution
CI2 + 2NaBr 2NaCI→ + Br2
Redox rxn gallium beating heart
Result
F2 + 2KCI -> 2KF + CI2
CI2 + 2KBr -> 2KCI + Br2
Br2 + 2KI -> 2KBr + I2
Ag+ + CI- -> AgCI
Ag+ + Br- -> AgBr
Ag+ + I- -> AgI
Chemical Properties Group 17
Size increaseReaction with water
Click here video fluorine chemistry
shell
2.7
2.8.7
2.8.8.7
2.8.18.18.7
CI
F
Br
I
Ability attract electron decrease/EN lower
Reactivity decrease
Group 17 (Halogen)
Chemical reaction
CI2 + H2O -> HCI + HOCIBr2 + H2O -> HBr + HOBrI2 + H2O -> HI + HOI
Reaction with AgNO3
Adding AgNO3
AgCI – white pptAgBr - yellow cream pptAgI – yellow ppt
Kept in seal, reactiveFluorine – yellow gasChlorine – greenish gasBromine – brown liquidIodine – violet solid
Click here video on chlorine chemistry
Similar chemical property - decrease reactivityChlorine – dissolve quickly – yellowish HOCI Bromine – dissolve slowly – brown HOBrIodine – slightly soluble - brown HOI
Displacement Reaction
Reactive halogen displace less reactive halogen from its halide solution
Click here video displacement reaction
Strong oxidizing agent
Add NaBrAdd NaCIAdd NaIAdd NaCIAdd NaIAdd NaBr
violet solid
brown liquid
yellow gas
Click here video displacement rxn
Click here video displacement rxn
CI2 + 2NaBr -> 2NaCI + Br2 ✓
CI2 + 2NaI -> 2NaCI + I2 ✓Br2 + NaCI -> ✗Br2 + 2NaI -> 2NaBr + I2 ✓I2 + NaCI -> ✗I2 + NaBr -> ✗
Chemical Properties Group 17
Group 17 (Halogen)
greenish gas
Displacement Reaction
Reactive halogen displace less reactive halogen from its halide solution
CI2 in hexane Br2 in hexaneI2 in hexane
Br2 in hexane
I2 in hexane
I2 in hexane
CI2 + 2NaBr -> 2NaCI + Br2 CI2 + 2NaI -> 2NaCI + I2✗ Br2 + 2NaI -> 2NaBr + I2
✗ ✗
Strong oxidizing agent
2Li + CI2 -> 2LiCI2Na + CI2 -> 2NaCI2K + CI2 -> 2KCI
Chemical Properties Group 1
Size increaseReaction with water
4Li + O2 -> 2Li2O4Na + O2 -> 2Na2O4K + O2 -> 2K2O
Click here video potassium in water
shell
2.1
2.8.1
2.8.8.1
2.8.8.18.1
Na
Li
K
Rb
lose electron easily electropositive
Reactivity increase
Group 1 (Alkali Metal)
Chemical reaction
2Li + 2H2O -> 2LiOH + H2
2Na + 2H2O -> 2NaOH + H2
2K + 2H2O -> 2KOH + H2
Reaction with oxygen Reaction with halogen
Lithium – move slowly surface water – red flameSodium – move fast, hissing sound – yellow flamePotassium – move fast, ignite - lilac flameTurn red litmus blue- produce hydrogen gas Solution of metal hydroxide/alkaline produced
Click here video sodium in water
Similar chemical property but diff reactivityLithium –burn slowly , red flameSodium – burn brightly, yellow flamePotassium –burn very brightly, lilac flame
Kept in paraffin oil
Strong reducing agentReduce H+ ion to H2 gas(losing e to H+)
Strong reducing agent
Oxidizing agent using potassium chlorate
Redox (Oxidation and Reduction)
Oxidation – Gain of oxygen ↑
Oxidation – Loss of hydrogen ↓ Reduction – Gain of hydrogen ↑
Reduction – Loss of oxygen ↓
Oxidation Reduction
Gain oxygen ↑ Loss oxygen ↓
Gain oxidation Number ↑
Loss oxidation Number ↓
Loss hydrogen ↓ Gain hydrogen ↑
Loss electron ↓ Gain electron ↑
Ca + O2 CaO→ CH4 + 2O2 CO→ 2+ 2H2Ogain oxygen gain oxygen
Zn + CuO ZnO + Cu→ PbO + CO Pb + CO→ 2loss oxygen loss oxygen
H2S + CI2 S +2HCI →loss hydrogen
H2S + CI2 S + 2HCI →
Redox - Oxidation state change- Electron transfer
CH4 + 2O2 → CO2 + 2H2O
gain hydrogen
Zn + CuSO4 → ZnSO4 + Cu Zn + CI2 → ZnCI2
No gain/loss oxygen/hydrogen
Redox
gain oxygen
gain hydrogen
Reduction
Oxidation
Are these redox rxns?
Most rxn does not involve H2
and O2
carbon oxidized
Oxidation Reduction
Gain oxygen ↑ Loss oxygen ↓
Loss hydrogen ↓ Gain hydrogen ↑
Redox (Oxidation and Reduction)
Rxn involve gain/loss of oxygen/hydrogen
CH4 + 2O2 → CO2 + 2H2O
Gain hydrogen
oxygen reduced
gain oxygen
carbon oxidized
Rxn involve gain/loss of electron
Oxidation Reduction
Gain ON ↑ Loss ON ↓
Loss electron ↓ Gain electron ↑- broader definition- cover more rxn types
lead reduced
gain oxygen
carbon oxidized
(-4) (+4)
(0) (-2)
ON ↑
ON ↓oxygen reduced
carbon oxidized
(+2) (0)lead reduced
(+2) (+4)
CH4 + 2O2 → CO2 + 2H2O
ON ↑
ON ↓loss oxygen
PbO + CO Pb + CO→ 2PbO + CO Pb + CO→ 2
Oxidizing Agent Reducing Agent
Causes Oxidation Cause Reduction
Undergo reduction Undergo oxidation
Gain electron ↑ Loss electron ↓
Decrease oxidation number ↓
Increase oxidation number ↑
Oxidation Reduction
Gain oxygen ↑ Loss oxygen ↓
Gain oxidation Number ↑
Loss oxidation Number ↓
Loss hydrogen ↓ Gain hydrogen ↑
Loss electron ↓ Gain electron ↑Oxidizing Agent Reducing Agent
MnO4- Fe2+
Cr2O72- SO2
HNO3 I-
H2O2 H2S
CI2 SO3 2-
CI2 + 2KBr- 2KCI→ + Br2
3CuO + 2NH3 3H→ 2O+ 3Cu + N2
Redox (Oxidation and Reduction)
(+7) (+2)Mn red - ON ↓
(+2) Fe oxi – ON ↑ (+3)
MnO4- + Fe2+ + 8H+ Mn→ 2+ + Fe3+ 4H2O
Oxidizing agent ↓ Reduction
Reducing agent ↓ Oxidation
Oxidizing Agent
Reducing Agent
MnO4- Fe2+
Reduction Oxidation
Oxidizing Agent
Reducing Agent
CI2 Br-
Reduction Oxidation
Oxidizing agent ↓ Reduction
Reducing agent ↓ Oxidation
(0) CI red – ON ↓ (-1)
(-1) Br - oxi – ON ↑ (0)
Oxidizing Agent
Reducing Agent
CuO NH3
Reduction Oxidation
Reducing agent ↓ Oxidation
(-3) NH3 oxi – ON ↑ (0)
Oxidizing agent ↓ Reduction (+2) Cu red – ON ↓ (0)
2HCI + Zn H→ 2 + ZnCI2
(0) Zn oxi – ON ↑ (+2)Reducing agent ↓ Oxidation
Oxidizing agent ↓ Reduction
(+1) H red – ON ↓ (0)
Oxidizing Agent
Reducing Agent
HCI Zn
Reduction Oxidation
CI2 + 2KBr- 2KCI→ + Br2
3CuO + 2NH3 3H→ 2O+ 3Cu +N2
Redox (Oxidation and Reduction)
(+7) (+2)Mn red - ON ↓
(+2) Fe oxi – ON ↑ (+3)
MnO4- + 8H+ + Fe2+ Mn→ 2+ + Fe3+ 4H2O
Oxidizing agent ↓ Reduction
Reducing agent ↓ Oxidation
Oxidizing Agent Reduction
MnO4- + 5e Mn→ 2+
Oxidizing agent ↓ Reduction
Reducing agent ↓ Oxidation
(0) CI red – ON ↓ (-1)
(-1) Br - oxi – ON ↑ (0)
Reducing agent ↓ Oxidation
(-3) NH3 oxi – ON ↑ (0)
Oxidizing agent ↓ Reduction (+2) Cu red – ON ↓ (0)
2HCI + Zn H→ 2 + ZnCI2
(0) Zn oxi – ON ↑ (+2)Reducing agent ↓ Oxidation
Oxidizing agent ↓ Reduction
(+1) H red – ON ↓ (0)
Reducing Agent Oxidation
Fe 2+ Fe→ 2+ + e- Loss electronIncrease ON ↑
Gain electronDecrease ON ↓
Reducing Agent Oxidation
2Br - Br→ 2 + 2e-
Loss electronIncrease ON ↑
Oxidizing Agent Reduction
CI2 + 2e 2CI→ - Gain electron
Decrease ON ↓
Reducing Agent Oxidation
(NH3) -N3- N→ + 3e- Loss electronIncrease ON ↑
Oxidizing Agent Reduction
(CuO) Cu2+ + 2e Cu→Gain electronDecrease ON ↓
Reducing Agent Oxidation
Zn Zn→ 2+ + 2e- Loss electronIncrease ON ↑
Oxidizing Agent Reduction
2H+ + 2e H→ 2
Gain electronDecrease ON ↓
Redox (Oxidation and Reduction)
Half equations
Oxidation rxn
Oxidation half eqn Reduction half eqn
Loss electron ↓
Reduction rxn
Loss hydrogen ↓ Gain oxygen ↑ Gain ON ↑ Gain electron ↑ Gain hydrogen ↑ Loss oxygen ↓ Loss ON ↓
Oxidizing AgentReducing Agent
Oxidation rxn Reduction rxnlose electron
Zn + 2H+ H→ 2 + Zn2+
Zn Zn→ 2+ + 2e 2H+ + 2e H→ 2
(0) ON increase ↑ (+2)
Zn Zn→ 2+ + 2e2H+ + 2e H→ 2 2H+ + Zn Zn→ 2+ + H2
lose electron gain electron
(+1) ON decrease ↓ (0)
Complete full eqn
Zn + Cu2+ Zn→ 2+ + CuOxidation half eqn
Zn Zn→ 2+ + 2elose electron
(0) ON increase ↑ (+2)
Reduction half eqn
Cu2+ + 2e Cu→
(+2) ON decrease ↓ (0)
gain electron
Zn Zn→ 2+ + 2eCu2+ + 2e Cu→Cu2+ + Zn Zn→ 2+ + Cu
Half equations
Redox (Oxidation and Reduction)
Half equations
Oxidation half eqn Reduction half eqn
Zn Zn→ 2+ + 2e 2H+ + 2e H→ 2
(0) ON increase ↑ (+2)
Zn Zn→ 2+ + 2e2H+ + 2e H→ 2 2H+ + Zn Zn→ 2+ + H2
lose electron gain electron
(+1) ON decrease ↓ (0)
Complete full eqn
Oxidation half eqn
Zn Zn→ 2+ + 2elose electron
(0) ON increase ↑ (+2)
Reduction half eqn
Cu2+ + 2e Cu→
(+2) ON decrease ↓ (0)
gain electron Zn Zn→ 2+ + 2eCu2+ + 2e Cu→Cu2+ + Zn Zn→ 2+ + Cu
Half equations
Zn + 2HCI H→ 2 + ZnCI2
Zn + 2H+ + 2CI- H→ 2 + Zn2+ + 2CI -
Complete ionic/redox eqn
Zn + 2H+ H→ 2 + Zn2+
spectator ionsspectator ions
Zn + 2H+ H→ 2 + Zn2+
Zn + CuSO4 ZnSO→ 4 + Cu
Zn + Cu2++ SO42- Zn→ 2+ + SO4
2- + Cu
Complete full eqn
Complete ionic/redox eqn
spectator ions
Zn + Cu2+ Zn→ 2+ + Cu
Half equations Half equationsZn + Cu2+ Zn→ 2+ + Cu
Redox (Oxidation and Reduction)
Half equations
Oxidation half eqn Reduction half eqn
Mg Mg→ 2+ + 2e Pb2+ + 2e Pb→(0) ON increase ↑ (+2)
Mg Mg→ 2+ + 2ePb2+ + 2e Pb →Pb2+ + Mg Mg→ 2+ + Pb
lose electron gain electron
(+2) ON decrease ↓ (0)
Complete full eqn
Oxidation half eqn
2Br- Br→ 2 + 2e
lose electron
(-1) ON increase ↑ (0)
Reduction half eqn
CI2 + 2e 2CI→ -
(0) ON decrease ↓ (-1)
gain electron 2Br- Br→ 2
+ 2eCI2
+ 2e 2CI→ -
CI2 + 2Br- 2CI→ - + Br2
Half equations
Mg + PbO Pb→ + MgO
Mg + Pb2+ + O2- Pb → + Mg2+ + O 2-
Complete ionic/redox eqn
spectator ionsspectator ions
Mg + Pb2+ Pb→ + Mg2+
2KBr + CI2 Br→ 2 + 2KCI
2K+ + 2Br- + CI2 Br→ 2 + 2K+ + 2CI -
Complete full eqn
Complete ionic/redox eqn
spectator ions
2Br- + CI2 Br→ 2 + 2CI-
Half equations Half equations
Mg + Pb2+ Pb→ + Mg2+
2Br- + CI2 Br→ 2 + 2CI-
lose electron
MnO4- + 8H+ + 5Fe2+ Mn→ 2+ + 5Fe3+ + 4H2O
Constructing Half and complete redox equation
(+7) (+2)Mn red - ON ↓
(+2) Fe oxi – ON ↑ (+3)
MnO4- + 5Fe2+ + 8H+ Mn→ 2+ + 5Fe3+ + 4H2O
Oxidizing agent ↓ Reduction
Reducing agent ↓ Oxidation
Oxidizing Agent Reduction
MnO4- + 5e Mn→ 2+
Reducing Agent Oxidation
Fe 2+ Fe→ 2+ + e- Loss electronIncrease ON ↑
Gain electronDecrease ON ↓
Complete full eqnOxidation half eqnReduction half eqn
1. Balance # O -add H2O
2. Balance # H add H+
3. Balance # charges -add electrons
4. Balance # electron transfer
MnO4- Mn→ 2+
MnO4- Mn→ 2+ + 4H2O
MnO4- + 8H+ Mn→ 2++ 4H2O
MnO4- + 8H+ + 5e- Mn→ 2+ + 4H2O
Fe2+ Fe→ 3+
Fe2+ Fe→ 3+ + e-
5Fe2+ 5Fe→ 3+ + 5e-MnO4- + 8H+ + 5e- Mn→ 2+ + 4H2O
x 5x 1
MnO4- + 8H+ + 5e- Mn→ 2+ + 4H2O
5Fe2+ 5Fe→ 3+ + 5e-+
MnO4- - In acidic medium
- Strong oxidizing agentMnO4
- + 8H+ + 5Fe2+ Mn→ 2+ + 5Fe3+ 4H2O
2MnO4- + 5SO2+ 2H2O 2Mn→ 2+ + 5SO4
2- + 4H+
Constructing Half and complete redox equation
(+7) (+2)Mn red - ON ↓
(+4) SO2 oxi – ON ↑ (+6)
2MnO4- + 5SO2 + 2H2O 2Mn→ 2+ + 5SO4
2- + 4H+
Oxidizing agent ↓ Reduction
Reducing agent ↓ Oxidation
Oxidizing Agent Reduction
MnO4- + 5e Mn→ 2+
Reducing Agent Oxidation
SO2 SO→ 4
2- + 2e- Loss electronIncrease ON ↑
Gain electronDecrease ON ↓
Complete full eqnOxidation half eqnReduction half eqn
1. Balance # O - add H2O
2. Balance # H add H+
3. Balance # charges - add electrons
4. Balance # electron transfer
MnO4- Mn→ 2+
MnO4- Mn→ 2+ + 4H2O
MnO4- + 8H+ Mn→ 2++ 4H2O
MnO4- + 8H+ + 5e- Mn→ 2+ + 4H2O
SO2 SO→ 4
2-
2MnO4- + 16H+ + 10e- 2Mn→ 2+ + 8H2O
x 5x 2
2MnO4- + 16H+ + 10e- 2Mn→ 2+ + 8H2O
5SO2 + 10H2O 5SO→ 42- + 20H+ + 10e-+
2MnO4- + 5SO2 + 2H2O 2Mn→ 2+ + 5SO4
2- 4H+
SO2 + 2H2O SO→ 4
2-
SO2 + 2H2O SO→ 4
2- + 4H+
SO2 + 2H2O SO→ 4
2- + 4H+ + 2e-
5SO2 + 10H2O 5SO→ 4
2- + 20H+ + 10e-
2MnO4- + 5H2O2 + 6H+ 2Mn→ 2+ + 5O2
+ 8H2O
Constructing Half and complete redox equations
(+7) (+2)Mn red - ON ↓
(-1) H2O2 oxi – ON ↑ (0)
2MnO4- + 5H2O2 + 6H+ 2Mn→ 2+ + 5O2
+ 8H2OOxidizing agent ↓ Reduction
Reducing agent ↓ Oxidation
Oxidizing Agent Reduction
MnO4- + 5e Mn→ 2+
Reducing Agent Oxidation
H2O2 O→ 2
+ 2e- Loss electronIncrease ON ↑
Gain electronDecrease ON ↓
Complete full eqn Oxidation half eqnReduction half eqn
1. Balance # O - add H2O
2. Balance # H add H+
3. Balance # charges - add electrons
4. Balance # electron transfer
MnO4- Mn→ 2+
MnO4- Mn→ 2+ + 4H2O
MnO4- + 8H+ Mn→ 2++ 4H2O
MnO4- + 8H+ + 5e- Mn→ 2+ + 4H2O
2MnO4- + 16H+ + 10e- 2Mn→ 2+ + 8H2O
x 5x 2
2MnO4- + 16H+ + 10e- 2Mn→ 2+ + 8H2O
5H2O2 5O→ 2 + 10H+ + 10e-+
2MnO4- + 5H2O2 + 6H+ 2Mn→ 2+ + 5O2
+ 8H2O
H2O2 O→ 2
H2O2 O→ 2 + 2H+
H2O2 O→ 2 + 2H+ + 2e-
5H2O2 5O→ 2 + 10H+ + 10e-
Cr2O72- + 3NO2
- + 8H+ 2Cr→ 3+ + 3NO3- + 4H2O
Cr2O72- 2Cr→ 3+
Constructing Half and complete redox equations
(+6) (+3)Cr red - ON ↓
(+3) NO2- oxi – ON ↑ (+5)
Cr2O72- + 3NO2
- + 8H+ 2Cr→ 3+ + 3NO3- + 4H2O
Oxidizing agent ↓ Reduction
Reducing agent ↓ Oxidation
Oxidizing Agent Reduction
Cr2O72- + 6e- 2Cr→ 3+
Reducing Agent Oxidation
NO2- NO→ 3
- + 2e- Loss electronIncrease ON ↑
Gain electronDecrease ON ↓
Complete full eqnOxidation half eqnReduction half eqn
1. Balance # O - add H2O
2. Balance # H add H+
3. Balance # charges - add electrons
4. Balance # electron transferx 3x 1
Cr2O72- + 14H+ + 6e- 2Cr→ 3+ + 7H2O
3NO2-+ 3H2O 3NO→ 3
- + 6H+ + 6e-+
Cr2O72- + 3NO2
- + 8H+ 2Cr→ 3+ + 3NO3- + 4H2O
Cr2O72- 2Cr→ 3+ + 7H2O
Cr2O72- + 14H+ 2Cr→ 3+ + 7H2O
Cr2O72- + 14H+ + 6e- 2Cr→ 3+ + 7H2O
Cr2O72- + 14H+ + 6e- 2Cr→ 3+ + 7H2O
NO2- NO→ 3
-
NO2- + H2O NO→ 3
-
NO2- + H2O NO→ 3
- + 2H+
NO2- + H2O NO→ 3
- + 2H+ + 2e-
3NO2- + 3H2O 3NO→ 3
- + 6H+ + 6e-
Cr2O72- + 6Fe2+ + 14H+ 2Cr→ 3+ + 6Fe3+ + 7H2O
Cr2O72- 2Cr→ 3+
Constructing Half and complete redox equations
(+6) (+3)Cr red - ON ↓
(+2) Fe2+ oxi – ON ↑ (+3)
Cr2O72- + 6Fe2+ + 14H+ 2Cr→ 3+ + 6Fe3+ + 7H2O
Oxidizing agent ↓ Reduction
Reducing agent ↓ Oxidation
Oxidizing Agent Reduction
Cr2O72- + 6e- 2Cr→ 3+
Reducing Agent Oxidation
Fe2+ Fe→ 3+ + e- Loss electronIncrease ON ↑
Gain electronDecrease ON ↓
Complete full eqnOxidation half eqnReduction half eqn
1. Balance # O - add H2O
2. Balance # H add H+
3. Balance # charges - add electrons
4. Balance # electron transferx 6x 1
Cr2O72- + 14H+ + 6e- 2Cr→ 3+ + 7H2O
6Fe2+ 6Fe→ 3+ + 6e-+
Cr2O72- 2Cr→ 3+ + 7H2O
Cr2O72- + 14H+ 2Cr→ 3+ + 7H2O
Cr2O72- + 14H+ + 6e- 2Cr→ 3+ + 7H2O
Cr2O72- + 14H+ + 6e- 2Cr→ 3+ + 7H2O
Cr2O72- + 6Fe2+ + 14H+ 2Cr→ 3+ + 6Fe3+ 7H2O
Fe2+ Fe→ 3+
Fe2+ Fe→ 3+ + e
6Fe2+ 6Fe→ 3+ + 6e
Constructing Half and complete redox equations
(+5) (-1)CIO3 - red - ON ↓
(-1) I- oxi – ON ↑ (0)
CIO3- + 6I- + 6H+ 3I→ 2 + CI- + 3H2O
Oxidizing agent ↓ Reduction
Reducing agent ↓ Oxidation
Oxidizing Agent Reduction
CIO3- + 6e- CI→ -
Reducing Agent Oxidation
2I- I→ 2 + 2e- Loss electron
Increase ON ↑
Gain electronDecrease ON ↓
Complete full eqnOxidation half eqnReduction half eqn
1. Balance # O - add H2O
2. Balance # H add H+
3. Balance # charges - add electrons
4. Balance # electron transferx 3x 1
CIO3- + 6H+ + 6e- CI→ - + 3H2O
6I- 3I→ 2 + 6e-+
CIO3- + 6I- + 6H+ 3I→ 2 + CI- + 3H2O
CIO3- CI→ -
CIO3- CI→ - + 3H2O
CIO3- + 6H+ CI→ - + 3H2O
CIO3- + 6H+ + 6e- CI→ - + 3H2O
CIO3- + 6H+ + 6e- CI→ - + 3H2O
2I- I→ 2
2I- I→ 2 + 2e-
6I- 3I→ 2 + 6e-
CIO3- + 6H++ 6I- 3I→ 2 + 3H2O
Constructing Half and complete redox equations
(+5) (+2) NO3 - red - ON ↓
(0) Cu oxi – ON ↑ (+2)
2NO3- + 3Cu + 8H+ 3Cu→ 2+ + 2NO + 4H2O
Oxidizing agent ↓ Reduction
Reducing agent ↓ Oxidation
Oxidizing Agent Reduction
NO3- + 3e- NO→
Reducing Agent Oxidation
Cu Cu→ 2+ + 2e- Loss electronIncrease ON ↑
Gain electronDecrease ON ↓
Complete full eqnOxidation half eqnReduction half eqn
1. Balance # O - add H2O
2. Balance # H add H+
3. Balance # charges - add electrons
4. Balance # electron transferx 3x 2
2NO3- + 8H+ + 6e- 2NO→ + 4H2O
3Cu 3Cu→ 2+ + 6e-+
2NO3- + 3Cu + 8H+ 3Cu→ 2+ + 2NO + 4H2O
NO3- NO→
NO3- NO + 2H→ 2O
NO3- + 4H+ NO + 2H→ 2O
NO3- + 4H+ + 3e- NO + 2H→ 2O
2NO3- + 8H+ + 6e- 2NO + 4H→ 2O
Cu Cu→ 2+
Cu Cu→ 2+ + 2e-
3Cu 3Cu→ 2+ + 6e-
2NO3- + 8H+ + 3Cu 3Cu→ 2+ +2NO + 4H2O
HNO3 +3Fe2+ + 3H+ 3Fe→ 3+ + NO + 2H2O
Constructing Half and complete redox equations
(+5) (+2) HNO3 red - ON ↓
(+2) Fe oxi – ON ↑ (+3)
HNO3 + 3Fe2+ + 3H+ 3Fe→ 3+ + NO + 2H2O
Oxidizing agent ↓ Reduction
Reducing agent ↓ Oxidation
Oxidizing Agent Reduction
HNO3 + 3e- NO→
Reducing Agent Oxidation
Fe 2+ Fe→ 3+ + e- Loss electronIncrease ON ↑
Gain electronDecrease ON ↓
Complete full eqnOxidation half eqnReduction half eqn
1. Balance # O - add H2O
2. Balance # H add H+
3. Balance # charges - add electrons
4. Balance # electron transferx 3x 1
HNO3 + 3H+ + 3e- NO→ + 2H2O 3Fe2+ 3Fe→ 3+ + 3e-+
HNO3 NO + 2H→ 2O
HNO3+ 3H+ NO + 2H→ 2O
HNO3 + 3H+ + 3e- NO + 2H→ 2O
HNO3 + 3H+ + 3e- NO + 2H→ 2O
Fe2+ Fe→ 3+
HNO3 + 3Fe2+ + 3H+ 3Fe→ 3+ + NO + 2H2O
HNO3 NO→
Fe2+ Fe→ 3+ + e-
3Fe2+ 3Fe→ 3+ + 3e-
H2O2 + 2Fe2+ +2H+ 2Fe→ 3+ + 2H2O
Constructing Half and complete redox equations
(-1) (-2) H2O3 red - ON ↓
(+2) Fe oxi – ON ↑ (+3)
H2O2 + 2Fe2+ + 2H+ 2Fe→ 3+ + 2H2O
Oxidizing agent ↓ Reduction
Reducing agent ↓ Oxidation
Oxidizing Agent Reduction
H2O3 + e- H→ 2O
Reducing Agent Oxidation
Fe 2+ Fe→ 3+ + e- Loss electronIncrease ON ↑
Gain electronDecrease ON ↓
Complete full eqnOxidation half eqnReduction half eqn
1. Balance # O - add H2O
2. Balance # H add H+
3. Balance # charges - add electrons
4. Balance # electron transferx 2x 1
H2O2 + 2H+ + 2e- 2H→ 2O 2Fe2+ 2Fe→ 3+ + 2e-+
Fe2+ Fe→ 3+
Fe2+ Fe→ 3+ + e-
2Fe2+ 2Fe→ 3+ + 2e-
H2O2 + 2Fe2+ + 2H+ 2Fe→ 3+ + 2H2O
H2O2 H→ 2O
H2O2 2H→ 2O
H2O2 + 2H+ 2H→ 2O
H2O2 + 2H+ + 2e- 2H→ 2O
H2O2 + 2H+ + 2e- 2H→ 2O
CI2 + SO2 + 2H2O 2CI→ - + SO4
2- + 4H+
Constructing Half and complete redox equations
(0) (-1)CI2 red - ON ↓
(+4) SO2 oxi – ON ↑ (+6)
CI2 + SO2 + 2H2O 2CI→ - + SO4
2- + 4H+
Oxidizing agent ↓ Reduction
Reducing agent ↓ Oxidation
Oxidizing Agent Reduction
CI2 + 2e 2CI→ -
Reducing Agent Oxidation
SO2 SO→ 4
2- + 2e- Loss electronIncrease ON ↑
Gain electronDecrease ON ↓
Complete full eqnOxidation half eqnReduction half eqn
1. Balance # O - add H2O
2. Balance # H add H+
3. Balance # charges - add electrons
4. Balance # electron transfer
SO2 SO→ 4
2-
x 1x 1
CI2 + 2e- 2CI→ -
SO2 + 2H2O SO→ 42- + 4H+ + 2e-+
SO2 + 2H2O SO→ 4
2-
SO2 + 2H2O SO→ 4
2- + 4H+
SO2 + 2H2O SO→ 4
2- + 4H+ + 2e-
CI2 + SO2 + 2H2O 2CI→ - + SO4
2- + 4H+
CI2 2CI→ -
CI2 + 2e- 2CI→ -
CI2 + 2e- 2CI→ - SO2
+ 2H2O SO→ 42- + 4H+ + 2e-
MnO4- (Acidic medium)
- Strong oxidizing agent- Gain 5 e-
MnO4- - (Neutral medium)
- Moderate oxidizing agent- Gain 3 e
MnO4- + 2H2O + 3e- MnO→ 2 + 4OH-
MnO4- - (Basic medium)
- Weak oxidizing agent- Gain 1 e
Disproportional Reaction
Substance both oxidized and reduced simultaneouslySubstance acts as oxidizing and reducing agent
Redox Reaction
(-1) Br - oxi – ON ↑ (0)
(0) CI red – ON ↓ (-1)
CI2 + 2KBr- 2KCI→ + Br2
Reducing agent - oxidizedOxidizing agent – reduced
Oxidizing Agent
Reducing Agent
Concept Map
Redox Reaction in diff medium
(-1) H2O2 red – ON ↓ (-2)
H2O2 H→ 2O + 1/2O2
(-1) H2O2 oxi – ON ↑ (0)
(0) CI2 red – ON ↓ (-1)
CI2 + H2O HOCI→ + HCI
(0) CI2 oxi – ON ↑ (+1)
(+3) HNO2 red – ON ↓ (+2)
HNO2 HNO→ 3 + 2NO + 2H2O
(+3) HNO2 oxi – ON ↑ (+5)
Cu2SO4 CuSO→ 4
+ Cu
(+1) Cu red – ON ↓ (0)
(+1) Cu oxi – ON ↑ (+2)
MnO4- + 8H+ + 5e- Mn→ 2+ + 4H2O
(+7) ON decrease ↓ (+2)
(+7) ON decrease ↓ (+4)
MnO4- + e- MnO→ 4
2-
(+7) ON decrease ↓ (+6)
Sn2+ + 2Fe3+ Sn→ 4+ + 2Fe2+2Fe2+ + CI2 2Fe→ 3+ + 2CI-Ca + 2H+ Ca→ 2+ + H2
IB Redox Questions
Deduce half eqn of oxidation and reduction for the following
Ca + 2H+ Ca→ 2+ + H22Fe2+ + CI2
2Fe→ 3+ + 2CI- Sn2+ + 2Fe3+ Sn→ 4+ + 2Fe2+
0 +1 +2 0
Ca Ca→ 2+ + 2e
2H+ + 2e H→ 2
oxidation
reduction
+2 0 +3 -1
2Fe2+ Fe→ 3+ + 2e
CI2 + 2e 2CI→ -
oxidation
reduction
+2 +3 +4 +2
Sn2+ Sn→ 4+ + 2e
2Fe3+ + 2e 2Fe→ 2+
Substances acting as oxidizing and reducing agent
2MnO4- + 5H2O2 + 6H+ 2Mn→ 2+ + 5O2
+ 8H2O
H2O2 + 2Fe2+ + 2H+ 2Fe→ 3+ + 2H2O
H2O2 + 2I- + 2H+ I→ 2 + 2H2O
Oxidizing Agent Reducing Agent
MnO4- Fe2+
Cr2O72- SO2
HNO3 I-
H2O2 H2S
CI2 SO3 2-
Acidified H2O2 act as oxidizing agent- Oxidizes Fe2+ to Fe3+
- Oxidizes I- to I2
Acidified MnO4- act as more powerful oxidizing agent
-Oxidizes weaker oxidizing agent H2O2 to H2O and O2
- H2O2 act as reducing agent
Identify oxidizing and reducing agent for following rxn.
5As2O3 + 2MnO4
- + 16H+ 2Mn→ 2+ + 5As2O5 + 8H2O 2NO3- + 3Cu + 8H+ 3Cu→ 2+ + 2NO + 4H2O
Cr2O72- + 3NO2
- + 8H+ 2Cr→ 3+ + 3NO3- + 4H2O
1 2
3
oxidizing agent
oxidizing agent
oxidizing agent
reducing agent
reducing agent
reducing agent
Acknowledgements
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Prepared by Lawrence Kok
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