1. The
Breathalyzer

2. The
Breathalyzer

3. The Breathalyzer Reaction
C2H5OH Cr2O H+ → CH3COOH + Cr H2O
Ethanol Orange Acid Acetic Acid Green Water
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 mg/mL
Legal Limit New Driver mg/mL

4. Test tubes each contain 5 mL 0.25 M K2Cr2O7 + 5 mL of 6.0 M H2SO4
+ 1 drop of 0.10 M AgNO3 (catalyst) and 0, 1, 2, 3, 4, drops respectively
of 10.0 % ethanol.
0.000 %
0.05 %
0.10 %
0.15 %
0.20 %

5. Redox Titrations 
A redox titration is the same as an acid-base titration except it involves a redox reaction.
Reagents are chosen so that the reaction is spontaneous.
Pick a suitable reagent for redox titration involving IO3- in acid solution.
A F-
B I-
C SO42-
D Cl-

6. Pick the spontaneous reaction

7. 6. 75 mL of 0. 100 M KMnO4 is required to titrate 25. 0 mL of FeCl2
6.75 mL of M KMnO4 is required to titrate mL of FeCl2. Calculate the [Fe2+].
MnO H+ + 5Fe2+ → Mn H2O Fe3+ L
0.0250L
0.100 M
? M
L MnO4-
x mole
1 L
x 5 moles Fe2+
1 mole MnO4-
[Fe2+] = L
= M

8. Inert electrodes- look at the solution for the reactions
Write the anode and cathode reactions.
voltmeter
NaNO3aq) Pt Pt
Inert electrodes- look at the solution for the reactions
MnO4- in acid
H2O2(aq)

9. Cathode
Anode

10. Cathode: MnO4- + 8H+ + 5e- → Mn2+ + 4H2O
Anode: H2O2 → O H e-
What happens to the mass of the cathode?
Constant
What happens to the mass of the anode?
What happens to the pH of the cathode?
Increases
What happens to the pH of the anode?
Decreases

11. The Cathode will stay inert A non-inert Anode might oxidize
Non-Inert Electrodes
The Cathode will stay inert
A non-inert Anode might oxidize
DC Power
Cu might oxidize -
Cathode
Reduction
2H2O + 2e-→H2 +2OH-
-0.41 v Cu Cu K+
SO42-
H2O
K2SO4(aq)

12. You must look at the possible oxidation of:
SO42-
H2O Cu
Strongest Reducing Agent

13. The Cathode will stay inert A non-inert Anode might oxidize
Non-Inert Electrodes
The Cathode will stay inert
A non-inert Anode might oxidize
DC Power
Cu might oxidize Cu Cu K+
SO42-
H2O -
Cathode
Reduction
2H2O + 2e-→H2 +2OH-
-0.41 v +
Anode
Oxidation
Cu(s) → Cu e-
-0.34 v
K2SO4(aq)

14. Review of Cells
Electrochemical Electrolytic
Is a power supply Requires power supply
Spontaneous (+) Nonspontaneous (-)
Makes electricity Makes chemicals
Reduction is highest on Chart
Reduction is the –ve

15. 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.

16. Electrochemical Cell: Zn, Zn(NO3)2 II Cu, CuSO4
Complete the Chart
Electrochemical Cell: Zn, Zn(NO3)2 II Cu, CuSO4
Anode: Reaction:
Cathode: Reaction:
E0 = Zn
Zn(s) → Zn2+ + 2e-
0.76 v Cu
Cu e- → Cu(s)
0.34 v
1.10 v
Higher on reduction Chart

17. Electrolytic Cell: Molten AlCl3 Anode: Reaction: Cathode: Reaction:
Anode: Reaction:
Cathode: Reaction:
Al Cl- C
2Cl-
→ Cl2(g) + 2e-
-1.36 v
Al e- → Al(s)
-1.66 v C
E0 = v
MTV = v
The anode and cathode are inert C or Pt
Vowels: Anode Anion Oxidation
Consonants: Cathode Cation Reduction

18. Anode: Cathode: C C Anode Oxidation Anion or Water
 Electrolytic Cell: KBr(aq) K+ Br H2O
Anode:
Cathode:    C C
Anode Oxidation Anion or Water

19. Oxidation of water

20. Anode: 2Br- → Br2(g) + 2e- -1.09 v Cathode: C C
 Electrolytic Cell: KBr(aq) K+ Br H2O
Anode: 2Br- → Br2(g) + 2e v
Cathode:    C C
Anode Oxidation Anion or Water
Cathode Reduction Cation or water

22. Anode: 2Br- → Br2(g) + 2e- -1.09 v
 Electrolytic Cell: KBr(aq) K+ Br H2O
Anode: 2Br- → Br2(g) + 2e v
Cathode: 2H2O + 2e- → H2(g) + 2OH v    C C
E0 = v
MTV = v
Anode Oxidation Anion or Water
Cathode Reduction Cation or water

23. Is Al a reactive or non-reactive metal?
Look on page 8
Reactive as Al is a relatively strong reducing agent.
Why is Al used for boats, patio furniture, swing sets, and trucks boxes?
Al makes a clear transparent Al2O3 paint like coating that prevents further oxidation.

24. How to Fail a Breathalyzer Video 1
Drunks
Jeff Dunham