UNIVERSITI PENDIDIKAN SULTAN IDRIS (UPSI)

NAMA KURSUS

TEKNOLOGI KOMUNIKASI DAN MAKLUMAT DALAM KIMIA

KOD KURSUS

TKU 3023

TAJUK

SIMULATION : ELECTROCHEMISTRY ( GALVANIC CELL )

NAMA PENSYARAH

PN ASMAYATI YAHYA

NAMA NO MATRIK

WAN NUR AIN BINTI WAN MOHAMED KASBI D20081032255

NOR HIDAYAH BT ABDUL LATIFF D20081032346

ELECTROCHEMISTRY ( GALVANIC CELL )

Teacher’s Guide / Chemistry Form 4 / Simulation

SCIENTIFIC CONCEPT

Electrochemistry is the study of the inter conversion of electrical and chemical

energy. This conversion takes place in an electrochemical cell that may be a:

Voltaic Cell

Spontaneous reaction generate electrical energy.

Electrolytic Cell

Electrical energy is used to bring about a non spontaneous reaction.

Spontaneous redox reaction can serve as a source of energy in a voltaic cell. The cell

must be designed in such a way that oxidation occurs at one electrode (anode) with reduction

at the other electrode (cathode). The electrons produced at the anode (oxidation), must be

transferred to the cathode, where they are consumed (reduction). To do this, the electrons

move through an external circuit, where they do electrical work.

From the figure above, the movement of ions occurs through a salt bridge that

connecting the two beakers. The salt bridge shown is an inverted glass U- tube, plugged with

glass wool at each end. The tube is filled with a solution of a salt that takes no part in the

electrode reactions; potassium nitrate, KNO3 is frequently used. As current is drawn from the

cell, K+ ions move from the salt bridge into the cathode half- cell. At the same time, NO3- ions

move into the anode half- cell. In this way, electrical neutrality is maintained without Cu 2+

ions coming in contact with the Zn electrode, which would short- circuit the cell.

The cell notation for the above reaction is as follows:

Zn (s) Zn2+ (aq) Cu2+ (aq) Cu (s)

In this notation:

The anode reaction (oxidation) is shown at the left. Zn atoms are oxidized to Zn2+

ions.

The salt bridge (or other means of separating the half cells) is indicated by the symbol

The cathode reaction (reduction) is shown at the right. Cu2+ ions are reduced to Cu

atoms.

A single vertical line indicates a phase boundary, such as between a solid electrode

and an aqueous solution.

ENGAGE

Car Battery

The inside of a car battery is like a chemical factory. Chemical energy is stored and

then released as electrical energy. This is one of the application of galvanic cell.

How the car’s battery works as a galvanic cell?

- When a battery is connected to a complete electrical circuit, it releases its stored

energy in the formed of electricity. A car battery is not part of a complete

electrical circuit until a key is turned in the ignition. Once the key is turned, the

electrical circuit is complete, causing a chemical reaction takes place in the car

battery.

- Sulfuric acid and plates of lead metal and lead oxide react to form lead sulphate.

During this process, electricity is produced.

EMPOWER

Title : Electrochemical Cell.

Objective : To build electrochemical cell.

Introduction:

In an electrochemical cell, chemical energy is converted into electrical energy. This is

accomplished by using a spontaneous chemical reaction to generate an electric current, which

we can simply define here as electrons travelling though a wire.

To create the electrochemical cell, two half-reactions will be set up in different

containers. In one, an oxidation reaction will be used to generate a source of electrons. These

free electrons will travel, through an external circuit, to the second container and will cause

the reduction reaction to occur. The final requirement for complete electrochemical cell will

be a salt bridge that will permit ions to flow between the two half-cells, thus maintaining

electrically neutral solutions.

Apparatus:

a) 250 ml beaker ; 2 unit

b) Glass U- tube for salt bridge

c) Cotton plugs for salt bridge

d) Voltmeter

e) Copper wires with alligator clips

f) Steel wool ( to clean electrodes)

g) Metal electrodes ( Zinc and Copper)

Solutions:

a) 0.5 M Zn(NO3)2

b) 0.5 M Cu(NO3)2

c) 0.5 M NaNO3

Procedure :

1) Each half-cell will be created by placing a metal electrode in an electrolytic solution

containing the same metal's ions. For example the copper electrode will be placed in a

copper ( II ) nitrate solution. For each electrochemical cell you create you will require

two half-cells. Set these cells beside each other - they will be connected by the U-

tube.

2) Fill a beaker about two-thirds full of the electrolytic solution. Clean the electrode

using the steel wool, then place the electrode in its appropriate solution.

3) Clip one end of each copper wire to the two electrodes using the alligator clips.

4) Fill the U-tube with NaNO3 and stopper both ends with the cotton plugs. Turn the U-

tube upside down and place one end in each half-cell.

5) Touch the other end of the copper wires to the voltmeter terminals. If the indicator on

the voltmeter deflects in the wrong direction, switch the wires on the terminals. Read

the highest voltage reading obtained - you'll need to do this quickly after connecting

the wires to the voltmeter.

Results :

Questions:

1) For the electrochemical cell that you have created:

a. Write out the two half-reactions for electrochemical cell.

b. Identify each half-reaction as oxidation or reduction.

c. Identify each half-reaction as the anode and cathode.

d. Indicate the direction of the flow of electrons.

2) Using a Table of Standard Reduction Potentials, calculate the theoretical voltage for

the cell.

3) Compare the voltages you obtained with the theoretical voltage for each cell. What

are some reasons that would account for any differences?

Answers:

1) a. For the zinc electrode:

Zn (s) Zn2+ (aq) + 2e

For the copper electrode:

Cu2+ (aq) + 2e Cu (s)

b. Oxidation : Zinc

Reduction : Copper

c. Anode : Zinc

Cathode : Copper

d. Electrons are flow from anode to the cathode.

2) Theoretical voltage = 1.101 V

3) a. Existing of a dust on the electrodes.

b. Parallax error when taking reading of voltage from voltmeter.

ENHANCE

A lemon can be used to make a simple cell. The cell has a zinc strip, a copper strip,

and the acidic juice of the lemon as the electrolyte. It generates about one volt, but only a

very small amount of current. ( The voltage of a battery is determined by the materials used

as electrodes and electrolyte ).

Write the half- cell reaction for the figure above?

Identify which of the half- cell reaction acts as anode and cathode?

Write the overall equations for the reaction?

How electrons will be neutralized in this reaction without the presence of

salt bridge?

Give an example of the application of the cell?