Topic: Electrolytic Cell
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Chemical rxns can produce electricity = galvanic (voltaic) cell OR PowerPoint PPT Presentation


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Topic: Electrolytic Cell Do now: p.19 in packet, cross out # 19 and do # 20 and #21. must label anode/cathode . Chemical rxns can produce electricity = galvanic (voltaic) cell OR Electrical energy used to carry out chemical reactions= electrolytic cell .

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Chemical rxns can produce electricity = galvanic (voltaic) cell OR

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Chemical rxns can produce electricity galvanic voltaic cell or

Topic: Electrolytic CellDo now: p.19 in packet, cross out # 19 and do # 20 and #21. must label anode/cathode 


Chemical rxns can produce electricity galvanic voltaic cell or

  • Chemical rxns can produce electricity

    = galvanic (voltaic) cell

    OR

  • Electrical energy used to carry out chemical reactions= electrolytic cell

Electrolytic Cell need electrical energy so NONSPONTANEOUS


Chemical rxns can produce electricity galvanic voltaic cell or

Galvanic Cell

Chemical

Potential

Energy

Electrical

Potential

Energy

Electrolytic Cell

Galvanic cell is a battery

Electrolytic cell needs a battery


Chemical rxns can produce electricity galvanic voltaic cell or

Electrolytic Cells

  • Nonspontaneous

  • Need battery or power supply

  • Consumes energy = endothermic


Chemical rxns can produce electricity galvanic voltaic cell or

What’s the difference?

Battery in one.

Electrons in galvanic flowing from – to +

Electrons in electrylic flowing from + to -

e-  e-  e-

anode

catode

Electrolytic Cell

a Fat Red Cat ate an Ox

Use Table J, but opposite

More active metal = cathode = negative

Less active metal = anode = positive

Galvanic Cell

A Fat Red Cat ate an Ox

Use Table J

More active metal = anode = negative

Less active metal = cathode = positive


Chemical rxns can produce electricity galvanic voltaic cell or

NONSPONTANEOUS

e- flow Anode to Cathode

But from + to –

(opposite then we’d think)

That’s why we use the battery

SPONTANEOUS

e- flow Anode to Cathode

from – to +

(just like we’d think)

That’s why it’s spontaneous

 e- e-  e-


A pox on electrolytic cells

A POX on Electrolytic Cells

  • Anode – Positive – Oxidation

A pox = a disease

And electrolytic cell behave differently like they are diseased?!


Various types of electrolytic cells

Various types of electrolytic cells

  • Fused Salt Cells – used to purify metals

    (Fused means melted = molten salt cell)

  • Add NaCl (s) and melt it

  • Now NaCl (l)

  • Why melt it?!

  • Why add CaCl2(s)??!

  • Na+1 is reduce to Na(l)

  • Na(l) is less dense then NaCl(l) so it floats on top

  • 20,000 tons of Na are produce this way in the US every year

Molten b/c need ions

Lowers MP – don’t need as much heat


Fused salt cell molten salt cell

Fused Salt Cell (Molten salt cell)

+

-

e- e- e- e-

Gain electron

So reduced

So cathode

Na+

Cl-

Na+

Cl-

lose electron

So oxidized

So anode

(l)

2

Cl-+  Cl + 1 e-

2

Na+ + 1e- Na

2

BUT WAIT SOMETHING IS WRONG WITH OUR ANODE


Various types of electrolytic cells1

Various types of electrolytic cells

2. Electroplating

A layer of a second metal is deposited on the metal electrode that acts as the cathode

  • Used to enhance the appearance of metal objects and protect them from corrosion.


Various types of electrolytic cells2

Various types of electrolytic cells

2. Electroplating

  • cathode = object to be plated

  • anode - made of metal want to plate on object

  • solution: contains ions of plating metal


Chemical rxns can produce electricity galvanic voltaic cell or

+

-

lose electron

So oxidized

So anode

e- e- e- e-

Ag  Ag+ + 1e-

Gain electron

So reduced

So cathode

NO3-

Ag+ + 1e- Ag

NO3-


3 electrolysis of h 2 o

3. Electrolysis of H2O

H2 is produced at one electrode, O2 at the other.

2H2O + energy 2H2 + O2

Can you tell from the picture which electrode is producing H2?


What do every one of these have in common

What do every one of these have in common?


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