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Prepared by Lawrence Kok

Tutorial on Reactivity Series vs Electrochemical Series.

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+)

Oxidizing agent using potassium chlorate

Reactivity Gp 1

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 solReactivity series

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 metal

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

lithium

How fast rxn happen? (Kinetics)

Electrochemical Series

STANDARD Reduction potential – H2 as std

Oxidized sp ↔ Reduced sp Eθ/VLi+ + e- ↔ Li -3.04K+ + e- ↔ K -2.93Ca2+ + 2e- ↔ Ca -2.87Na+ + e- ↔ Na -2.71Mg 2+ + 2e- ↔ Mg -2.37Al3+ + 3e- ↔ AI -1.66Mn2+ + 2e- ↔ Mn -1.19H2O + e- ↔ H2+OH- -0.83Zn2+ + 2e- ↔ Zn -0.76Fe2+ + 2e- ↔ Fe -0.45Ni2+ + 2e- ↔ Ni -0.26Sn2+ + 2e- ↔ Sn -0.14Pb2+ + 2e- ↔ Pb -0.13H+ + e- ↔ 1/2H2 0.00Cu2+ + e- ↔ Cu+ +0.15SO4

2- + 4H+ + 2e- ↔ H2SO3 + H2O +0.17Cu2+ + 2e- ↔ Cu +0.341/2O2 + H2O +2e- ↔ 2OH- +0.40Cu+ + e- ↔ Cu +0.521/2I2 + e- ↔ I- +0.54Fe3+ + e- ↔ Fe2+ +0.77Ag+ + e- ↔ Ag +0.801/2Br2 + e- ↔ Br- +1.071/2O2 + 2H+ +2e- ↔ H2O +1.23Cr2O7

2-+14H+ +6e- ↔ 2Cr3+ +7H2O +1.331/2CI2 + e- ↔ CI- +1.36MnO4

- + 8H+ + 5e- ↔ Mn2+ + 4H2O +1.511/2F2 + e- ↔ F +2.87

-ve reduction potential

+ve reduction potential

Compared to H2 as std

Eθ cell/Cell Potential = EMF in voltEMF when half cell connect to SHE std conditionStd potential written as std reduction potential

TOP right• High ↑ tendency lose e• Li → Li + + e• Eθ Li = +3.04V• STRONG reducing Agent•Oxi favourable (Eθ =+ve)

TOP right• High ↑ tendency lose e• Li → Li + + e• Eθ Li = +3.04V• STRONG reducing Agent•Oxi favourable (Eθ =+ve)

STRONG Reducing Agent

WEAK Reducing Agent

BOTTOM right• Low ↓ tendency lose e• F - → 1/2F2 + e

• Eθ F2 = - 2.87V• WEAK reducing Agent•Oxi NOT favourable (Eθ =-ve)

BOTTOM right• Low ↓ tendency lose e• F - → 1/2F2 + e

• Eθ F2 = - 2.87V• WEAK reducing Agent•Oxi NOT favourable (Eθ =-ve)

WEAK Oxidizing Agent

StrongOxidizing Agent

TOP left• Low ↓ tendency gain e• Li+ + e → Li• Eθ Li= - 3.04V• WEAK oxidizing Agent• Red NOT favourable (Eθ =-ve)

TOP left• Low ↓ tendency gain e• Li+ + e → Li• Eθ Li= - 3.04V• WEAK oxidizing Agent• Red NOT favourable (Eθ =-ve)

BOTTOM left• High ↑ tendency gain e• F2 + 2e → 2F-

• Eθ F2= +2.87V• STRONG oxidizing Agent•Red favourable (Eθ =+ve)

BOTTOM left• High ↑ tendency gain e• F2 + 2e → 2F-

• Eθ F2= +2.87V• STRONG oxidizing Agent•Red favourable (Eθ =+ve)

Thermodynamics measurement

Reactivity Series

lithium Li

Potassium > Sodium > Lithium

Electrochemical Series

Reactivity vs Electrochemical Series

Oxidized sp ↔ Reduced sp Eθ/VLi+ + e- ↔ Li -3.04K+ + e- ↔ K -2.93Ca2+ + 2e- ↔ Ca -2.87Na+ + e- ↔ Na -2.71Mg 2+ + 2e- ↔ Mg -2.37Al3+ + 3e- ↔ AI -1.66Zn2+ + 2e- ↔ Zn -0.76Fe2+ + 2e- ↔ Fe -0.45Ni2+ + 2e- ↔ Ni -0.26Pb2+ + 2e- ↔ Pb -0.13Cu2+ + 2e- ↔ Cu +0.34Ag+ + e- ↔ Ag +0.80

Lithium > Potassium > Sodium

Electrochemical Series - Thermodynamics measurement↓

Eθ value give – energetics feasibility of rxn- not rate/kinetics↓

Rxn may be feasible, but to slow to happen/no observable sign – Ea too high

↓Measurement of voltage/potential using Std H2 Electrode

Reactivity – Kinetics ↓

How fast/metal with water and acid↓

Due to low Ea – easier to react↓

Potassium + water = faster/reactive Lithium + water = slower/less reactive

Strong Correlation but may not be the same↓

Li to Li+ ion more thermodynamically favourable than K to K+ ion↓

K more reactive than Li in water/acid – due to kinetics factor

Electrochemical Series - Thermodynamics measurementM(s) → M+

(g) + e

3 Steps rxn:M (s) → M (g) ∆H = enthalpy of atomization M (g) → M+ (g) ∆H = enthalpy of ionizationM+

(g) → M+(aq) ∆H = enthalpy of hydration

Electrochemical Series

STD Oxidation potential

Reduced sp ↔ Oxidized sp Eθ/VLi ↔ Li+ + e +3.04K ↔ K+ + e +2.93Na ↔ Na+ + e +2.71

Li(s)

Li → Li+(g)

∆Ha = +161

∆HI = +519 ∆Hhyd = - 499

Li+(g) → Li+

(aq)

Li(s) → Li + (aq) ∆H = +181

Li(s) → Li (g)

∆Ha = +90

K (s)

K (s) → K (g)

∆HI = +418 ∆Hhyd = - 305

K+(g) → K+

(aq)

K(s) → K +(aq) ∆H = +203

Na (s)

∆Ha = +108

Na(s) → Na(g)

∆HI = +494

K → K+(g)

Na → Na+(g)

∆Hhyd = - 390

Na+(g) → Na+

(aq)

Na(s) → Na+(aq) ∆H = +212

Lithium – least ∆H change - Most energetically favourable-∆H = spontaneous/favourable

-∆H = spontaneous/favourable↓

Li → Li + + e +Eθ

Potassium – High ∆H change - Less energetically favourable-∆H = spontaneous/favourable

-∆H = spontaneous/favourable↓

K → K + + e +Eθ

Sodium – Highest ∆H change - Least energetically favourable

+∆H = NON spontaneous/favourable

+∆H = NON spontaneous/favourable↓

Na → Na + + e +Eθ

Li NaK

Lithium – Size smaller ↓

Easily hydrated → - ∆H favourable↓

IE High – strong NC due to small size

Potassium– Size bigger↓

Diff hydrated → +∆H non favourable↓

IE Low – weak NC due to large size

Electrochemical Series STD Oxidation potential

Reduced sp ↔ Oxidized sp Eθ/VLi ↔ Li+ + e +3.04K ↔ K+ + e +2.93Na ↔ Na+ + e +2.71

Li(s)

Li → Li+(g)

∆Ha = +161

∆HI = +519 ∆Hhyd = - 499

Li+(g) → Li+

(aq)

Li(s) → Li + (aq) ∆H = +181

Li(s) → Li (g)

∆Ha = +90

K (s)

K (s) → K (g)

∆HI = +418 ∆Hhyd = - 305

K+(g) → K+

(aq)

K(s) → K +(aq) ∆H = +203

Na (s)

∆Ha = +108

Na(s) → Na(g)

∆HI = +494

K → K+(g)

Na → Na+(g)

∆Hhyd = - 390

Na+(g) → Na+

(aq)

Na(s) → Na+(aq) ∆H = +212

Lithium – least ∆H change - Most energetically favourable-∆H = spontaneous/favourable

-∆H = spontaneous/favourable↓

Li → Li + + e +Eθ

Potassium – High ∆H change - Less energetically favourable-∆H = spontaneous/favourable

-∆H = spontaneous/favourable↓

K → K + + e +Eθ

Sodium – Highest ∆H change - Least energetically favourable

+∆H = NON spontaneous/favourable

+∆H = NON spontaneous/favourable↓

Na → Na + + e +Eθ

Reactivity Series

Potassium > Sodium > Lithium Lithium > Potassium > Sodium

vs

Reactivity vs Electrochemical Series

Lithium is above Potassium in electrochemical series ↓

Lithium is below Potassium in Reactivity Series↓

Due to kinetics factors/activation energy, Rxn is slower

Potassium KSodium NaLithium Li

Acknowledgements

Thanks to source of pictures and video used in this presentation

Thanks to Creative Commons for excellent contribution on licenseshttp://creativecommons.org/licenses/

Prepared by Lawrence Kok

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