3.2 e: Galvanic Cells

Galvanic Cells Basics

Year 11 Chemistry

​Syllabus dot points

• 3.2 e conduct investigations to measure and compare the reduction potential of galvanic half-cells

​What we will cover

• What is a galvanic cells/types

• Parts of a galvanic cell

• ​How to draw

​What is a galvanic cell?

​A device where a chemical reaction occurs that produces electricity

​

• ​Batteries are galvanic cells

• ​Conversion of chemical energy into electrical energy

• Uses redox reactions because of the movement of electrons

  • the electrons flow through a set up wire and generate a current/electricity

​Galvanic or Voltaic Cell?

Both names are used to describe the same device - but why?

​

​Luigi Galvani and Alessandro Volta both came up with the same system!

​Parts of a Galvanic Cell

• ​Electrodes

  • Cathode - where reduction occurs

  • Anode ​- where oxidation occurs

• Solutions

  • an electrolyte solution that can conduct electricity

• Salt bridge

  • provides electric​al contact between the two solutions/half cells

  • something containing an electrolyte solution

​How does a galvanic cell work?

• Metal electrodes are placed in their respective electrolyte solutions

• ​The redox reactions begin

• In this example:

  • The zinc anode is where oxidation occurs - zinc enters the solution from the electrode - loss

  • The copper cathode is where reduction occurs - copper attaches to the electrode from the solution - gain

• Electrons flow between two half cells, from negative terminal to positive terminal

• The salt bridge completes the circuit

​Drawing a galvanic cell

• ​two half cells

• salt bridge

• wire + bulb/voltmeter

• labelling:

  • electrodes

  • solutions

  • direction of electrons

  • movement of ions

• sometimes: the half reactions

​Draw the following galvanic cell:

​Include:

• all experimental set up (incl. a bulb)

• ​labels of cathode and anode

• labels of solutions

• direction of electron flow

• half reactions occurring at each electrode

• the migration of ions within each half cell ​

Multiple Choice

In a Galvanic Cell, the anode is...

• positive

• negative

Multiple Choice

In a Galvanic Cell, the cathode is...

• positive

• negative

Multiple Choice

Oxidation occurs at the...

• anode

• cathode

Multiple Choice

Reduction occurs at the...

• anode

• cathode

Multiple Choice

In a Galvanic cell, the electrons flow from the...

• anode to the cathode

• cathode to the anode

Multiple Choice

In a Galvanic Cell, the salt bridge...

• completes the circuit so that electrons can flow through the wire

• maintains charge balance

• is soaked in an unreactive electrolyte such as KNO₃

• all of the above

Multiple Choice

In the above Galvanic Cell, which half cell is undergoing reduction?

• Cu | Cu²⁺

• Zn | Zn²⁺

Multiple Choice

A certain galvanic cell has for its spontaneous cell reaction: Zn + HgO → ZnO + Hg

Which is the half-reaction occurring at the anode?

• HgO + 2 e- → Hg + O^2-

• Zn²⁺ + 2 e- → Zn

• Zn → Zn²⁺ + 2 e-

• ZnO + 2 e- → Zn

Multiple Choice

A certain galvanic cell has for its spontaneous cell reaction: Zn + HgO → ZnO + Hg

Which is the half-reaction occurring at the cathode?

• HgO + 2 e- → Hg + O^2-

• Hg → Hg²⁺ + 2 e-

• Zn → Zn²⁺ + 2 e-

• ZnO + 2 e- → Zn

​Up next:

• Standard electrode potentials

• ​calculating voltages