The Breathalyser Reaction 

 C2H2OH + Cr2O7

2- → CH3COOH + Cr3+

 Ethanol Orange Acetic Acid Green If the orange colour decreases there is alcohol present. It is measured with a spectrophotometer. The more it decreases, the higher the blood alcohol content.  Legal Limit Class 5 Licence 0.08 mg/mLLegal Limit New Driver 0.00 mg/mL Substance OxidizedSubstance ReducedReducing AgentOxidizing Agent 

The Breathalyser ReactionLook at the oxidation numbers!-0.5   +6 0 +3

C2H2OH + Cr2O72- → CH3COOH + Cr3+

 Ethanol Orange Acetic Acid Green If the orange colour decreases there is alcohol present. It is measured with a spectrophotometer. The more it decreases, the higher the blood alcohol content.  Legal Limit Class 5 Licence 0.08 mg/mLLegal Limit New Driver 0.00 mg/mL Substance OxidizedSubstance ReducedReducing AgentOxidizing Agent 

The Breathalyser ReactionLook at the oxidation numbers!-0.5   +6 0 +3

C2H2OH + Cr2O72- → CH3COOH + Cr3+

 Ethanol Orange Acetic Acid Green If the orange colour decreases there is alcohol present. It is measured with a spectrophotometer. The more it decreases, the higher the blood alcohol content.  Legal Limit Class 5 Licence 0.08 mg/mLLegal Limit New Driver 0.00 mg/mL Substance Oxidized C2H2OH Substance ReducedReducing AgentOxidizing Agent 

The Breathalyser ReactionLook at the oxidation numbers!-0.5   +6 0 +3

C2H2OH + Cr2O72- → CH3COOH + Cr3+

 Ethanol Orange Acetic Acid Green If the orange colour decreases there is alcohol present. It is measured with a spectrophotometer. The more it decreases, the higher the blood alcohol content.  Legal Limit Class 5 Licence 0.08 mg/mLLegal Limit New Driver 0.00 mg/mL Substance Oxidized C2H2OH Substance ReducedReducing Agent C2H2OH Oxidizing Agent 

The Breathalyser ReactionLook at the oxidation numbers!-0.5   +6 0 +3

C2H2OH + Cr2O72- → CH3COOH + Cr3+

 Ethanol Orange Acetic Acid Green If the orange colour decreases there is alcohol present. It is measured with a spectrophotometer. The more it decreases, the higher the blood alcohol content.  Legal Limit Class 5 Licence 0.08 mg/mLLegal Limit New Driver 0.00 mg/mL Substance Oxidized C2H2OH Substance Reduced Cr2O7

2-

Reducing Agent C2H2OH Oxidizing Agent  

The Breathalyser ReactionLook at the oxidation numbers!-0.5   +6 0 +3

C2H2OH + Cr2O72- → CH3COOH + Cr3+

 Ethanol Orange Acetic Acid Green If the orange colour decreases there is alcohol present. It is measured with a spectrophotometer. The more it decreases, the higher the blood alcohol content.  Legal Limit Class 5 Licence 0.08 mg/mLLegal Limit New Driver 0.00 mg/mL Substance Oxidized C2H2OH Substance Reduced Cr2O7

2-

Reducing Agent C2H2OH Oxidizing Agent Cr2O7

2-  

Balance in acid solution

 C2H2OH + Cr2O7

2- → CH3COOH + Cr3+

Balance in acid solution

 C2H2OH + Cr2O7

2- → CH3COOH + Cr3+

Cr2O72- → Cr3+

C2H2OH → CH3COOH

Balance in acid solution

 C2H2OH + Cr2O7

2- → CH3COOH + Cr3+

Cr2O72- → 2Cr3+

C2H2OH → CH3COOH

Balance in acid solution

 C2H2OH + Cr2O7

2- → CH3COOH + Cr3+

Cr2O72- → 2Cr3+ + 7H2O

C2H2OH + H2O → CH3COOH

Balance in acid solution

 C2H2OH + Cr2O7

2- → CH3COOH + Cr3+

14H+ + Cr2O72- + → 2Cr3+ + 7H2O

C2H2OH + H2O → CH3COOH + H+

Balance in acid solution

 C2H2OH + Cr2O7

2- → CH3COOH + Cr3+

14H+ + Cr2O72- + 6e- → 2Cr3+ + 7H2O

C2H2OH + H2O → CH3COOH + H+ + 1e-

Balance in acid solution

 C2H2OH + Cr2O7

2- → CH3COOH + Cr3+

14H+ + Cr2O72- + 6e- → 2Cr3+ + 7H2O

6(C2H2OH + H2O→ CH3COOH+ H+ + 1e-)

Balance in acid solution

 C2H2OH + Cr2O7

2- → CH3COOH + Cr3+

14H+ + Cr2O72- + 6e- → 2Cr3+ + 7H2O

6(C2H2OH + H2O→ CH3COOH+ H+ + 1e-)

14H+ + Cr2O72- + 6C2H2OH + 6H2O → 2Cr3++7H2O+6CH3COOH+6H+

Balance in acid solution

 C2H2OH + Cr2O7

2- → CH3COOH + Cr3+

14H+ + Cr2O72- + 6e- → 2Cr3+ + 7H2O

6(C2H2OH + H2O→ CH3COOH+ H+ + 1e-)

8 114H+ + Cr2O7

2- + 6C2H2OH + 6H2O → 2Cr3++7H2O+6CH3COOH+6H+

Balance in acid solution

 C2H2OH + Cr2O7

2- → CH3COOH + Cr3+

14H+ + Cr2O72- + 6e- → 2Cr3+ + 7H2O

6(C2H2OH + H2O→ CH3COOH+ H+ + 1e-)

8H+ + Cr2O72- + 6C2H2OH → 2Cr3+ + 1H2O + 6CH3COOH

Balance in acid solution

 C2H2OH + Cr2O7

2- → CH3COOH + Cr3+

14H+ + Cr2O72- + 6e- → 2Cr3+ + 7H2O

6(C2H2OH + H2O→ CH3COOH+ H+ + 1e-)

8H+ + Cr2O72- + 6C2H2OH → 2Cr3+ + 1H2O + 6CH3COOH

+6 +6

Balance in base solution

8H+ + Cr2O72- + 6C2H2OH → 2Cr3+ + 1H2O + 6CH3COOH

Balance in base solution

8H+ + Cr2O72- + 6C2H2OH → 2Cr3+ + 1H2O + 6CH3COOH

8OH- 8OH-

Balance in base solution

 

8H+ + Cr2O72- + 6C2H2OH → 2Cr3+ + 1H2O + 6CH3COOH

8OH- 8H2O 8OH-

Balance in base solution

 

8H+ + Cr2O72- + 6C2H2OH → 2Cr3+ + 1H2O + 6CH3COOH

8OH- 8H2O 8OH-

Balance in base solution

 

Cr2O72- + 6C2H2OH → 2Cr3 + 1H2O + 6CH3COOH + 8OH-

7 8H2O

Balance in base solution

 

7H2O + Cr2O72- + 6C2H2OH → 2Cr3+ + 6CH3COOH + 8OH-

Review of Cells

Electrochemical Electrolytic Is a power supply Requires power supplySpontaneous (+ ve) Nonspontaneous(-ve)Makes electricity Makes chemicals Reduction is highest on Chart Reduction is the –ve

For all cells:

Cations migrate to the cathode, which is the site of reduction. Anions migrate to the anode, which is the site of oxidation.  Electrons travel through the wire from anode to cathode.

Complete the Chart Electrochemical Cell: Zn, Zn(NO3)2 II Cu, CuSO4

 

Anode: Reaction: 

Cathode: Reaction:

E0 =

 

Complete the Chart Electrochemical Cell: Zn, Zn(NO3)2 II Cu, CuSO4

 

Anode: Zn Reaction: 

Cathode: Cu Reaction:

E0 =

Higher on reduction Chart

 

Complete the Chart Electrochemical Cell: Zn, Zn(NO3)2 II Cu, CuSO4

 

Anode: Zn Reaction: Zn → Zn2+ + 2e- 0.76 v 

Cathode: Cu Reaction:

E0 =

Higher on reduction Chart

 

Complete the Chart Electrochemical Cell: Zn, Zn(NO3)2 II Cu, CuSO4

 

Anode: Zn Reaction: Zn(s) → Zn2+ + 2e- 0.76 v 

Cathode: Cu Reaction: Cu2+ + 2e- → Cu(s) 0.34 v

E0 =  Higher on reduction Chart

 

Complete the Chart Electrochemical Cell: Zn, Zn(NO3)2 II Cu, CuSO4

 

Anode: Zn Reaction: Zn → Zn2+ + 2e- 0.76 v 

Cathode: Cu Reaction: Cu2+ + 2e- → Cu(s) 0.34 v

E0 = 1.10 v   Higher on reduction Chart

 

   

Electrolytic Cell: Molten AlCl3

 Anode: Reaction: Cathode: Reaction: 

 

 

   

Electrolytic Cell: Molten AlCl3 Al3+ Cl-

 Anode: C Reaction: Cathode: C Reaction: 

 

 

   

Electrolytic Cell: Molten AlCl3 Al3+ Cl-

 Anode: C Reaction: Cathode: C Reaction: 

 Put the vowels together: AnodeAnionOxidation

 

   

Electrolytic Cell: Molten AlCl3 Al3+ Cl-

 Anode: C Reaction: 2Cl- → Cl2 + 2e- -1.36 v Cathode: C Reaction: 

 Put the vowels together: AnodeAnionOxidation

Oxidation of Anion

 

   

Electrolytic Cell: Molten AlCl3

 Anode: C Reaction: 2Cl- → Cl2 + 2e- -1.36 v Cathode: C Reaction:  

 Put the consonants together: CathodeCationReduction

 

   

Electrolytic Cell: Molten AlCl3

 Anode: C Reaction: 2Cl- → Cl2 + 2e- -1.36 v Cathode: C Reaction: Al3+ + 3e- → Al -1.66 v 

 Put the consonants together: CathodeCationReduction

Reduction of Cation

 

   

Electrolytic Cell: Molten AlCl3

 Anode: C Reaction: 2Cl- → Cl2 + 2e- -1.36 v Cathode: C Reaction: Al3+ + 3e- → Al -1.66 v E0 = -3.02 v 

 

   

Electrolytic Cell: Molten AlCl3

 Anode: C Reaction: 2Cl- → Cl2 + 2e- -1.36 v Cathode: C Reaction: Al3+ + 3e- → Al -1.66 v E0 = -3.02 v MTV = +3.02 v

 

 Electrolytic Cell: KBr(aq)

 

Anode: Cathode: 

 

  

 

 Electrolytic Cell: KBr(aq) K+ Br- H2O 

Anode: C Cathode: C 

 

  

 

 Electrolytic Cell: KBr(aq) K+ Br- H2O 

Anode: C Cathode: C 

 

 Put the vowels together: AnodeAnion or waterOxidation 

 

 Electrolytic Cell: KBr(aq)

 

Anode: C 2Br- → Br2 + 2e- -1.09 v Cathode: C 

 

  

Oxidation of Anion or WaterTake Lower one!

 

 Electrolytic Cell: KBr(aq)

 

Anode: C 2Br- → Br2 + 2e- -1.09 v Cathode: C 

 

Put the consonants together: CathodeCation or waterReduction

Oxidation of Anion or WaterTake Lower one!

 

 Electrolytic Cell: KBr(aq)

 

Anode: C 2Br- → Br2 + 2e- -1.09 v Cathode: C 2H2O + 2e- → H2 + 2OH- -0.41 v 

 

Put the consonants together: CathodeCation or waterReduction

Oxidation of Anion or WaterTake Lower one!

Reduction of Cation or WaterTake Higher one!

 

 Electrolytic Cell: KBr(aq)

 

Anode: C 2Br- → Br2 + 2e- -1.09 v Cathode: C 2H2O + 2e- → H2 + 2OH- -0.41 v E0 = -1.50 v 

  

Oxidation of Anion or WaterTake Lower one!

Reduction of Cation or WaterTake Higher one!

 

 Electrolytic Cell: KBr(aq)

 

Anode: C 2Br- → Br2 + 2e- -1.09 v Cathode: C 2H2O + 2e- → H2 + 2OH- -0.41 v E0 = -1.50 v MTV = +1.50 v  

Oxidation of Anion or WaterTake Lower one!

Reduction of Cation or WaterTake Higher one!

 

 Electrochemical Cell: Ag, AgNO3 II Sn, Sn(NO3)2

 

Cathode:  Anode: 

 

 Electrochemical Cell: Ag, AgNO3 II Sn, Sn(NO3)2

 *higher

Cathode: Ag  Anode: 

 

 Electrochemical Cell: Ag, AgNO3 II Sn, Sn(NO3)2

 *higher

Cathode: Ag Ag+ + e- → Ag(s) +0.80 v Anode: 

 

 Electrochemical Cell: Ag, AgNO3 II Sn, Sn(NO3)2

 *higher

Cathode: Ag Ag+ + e- → Ag(s) +0.80 v Anode: Sn 

 

 Electrochemical Cell: Ag, AgNO3 II Sn, Sn(NO3)2

 *higher

Cathode: Ag Ag+ + e- → Ag(s) +0.80 v Anode: Sn Sn → Sn2+ + 2e- +0.14 v 

 

 Electrochemical Cell: Ag, AgNO3 II Sn, Sn(NO3)2

 *higher

Cathode: Ag 2(Ag+ + e- → Ag(s)) +0.80 v Anode: Sn Sn → Sn2+ + 2e- +0.14 v 2Ag+ + Sn → Sn2+ + 2Ag(s) E0 = 0.94 v