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ELECTRODEPOSITION AND ELECTROCHEMICAL DEVICES (MATERIAL in TASK A : (Zinc…
ELECTRODEPOSITION AND ELECTROCHEMICAL DEVICES
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AIM
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Prepare pure material using electrodeposition.
Investigate in detail of redox reaction by cyclic voltammetric
Purposes of electroplating
ii. Special surface properties
iii. Appearances
i. Protection against corrosion
iv. Mechanical Properties
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ELECTROPLATING
A process in which metal object is coated with another metal such as zinc, silver or chromium to change the surface properties of metals. Metal is deposited electrochemically from a solution of its own ions.
Also called “electrodeposition”, a short version of “electrolytic deposition”
Electrolyte
Properties of electrolyte
Hardness
Resistance
Brightness or reflectivity
Mechanical strength
Ductility
Wear resistance
Corrositivity
A substance that produces an electrically conducting solution
MATERIAL in TASK A
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Zinc Electrode
Carbon Elecrode
A.D.C Power Supply
2 Multimeter
Connecting wires
ZnSO4 Solution
3-neck Flask
Weighing Scale
Sand Paper
PROCEDURE TASK A:
(1) The anode and cathode are polished by using silicon carbide paper up to 1200 grit.
(2)Then the electrodes are weighed using precision electronic balance as they were used for measuring the current efficiency.
(3) Zinc deposition area which are 1 x 1 cm is mark by using musking tape on copper cathode
(4) After electric circuit for the cell is prepared as shown in figure 8.1, the electrolyte solution is poured into the 3-neck flask.
(5)The cathode is connected to the D.C. power supply terminal then it immersed into the electrolyte. The D.C. power supply is turned on and the current is adjusted to 0.05 A. deposition time of 30 minutes is allowed to take place
(6)Cathode is taken out of the solution after deposition and then the rectifier was switched off
(7) Zinc deposit is washed carefully then rinsed with ethano and let dried. The cathode is weighed with the deposited zinc after ensuring there is no water and ethanol present on the cathode during weighing session
(8) Data and calculation are recorded in the table
This experiment is divided into two parts
Hands on laboratory
Machinary which is Cyclic Voltammetric (CV)
MATERIAL in TASK B
Autolab Machine
Carbon Electrode
SCE Electrode
Same as in Task A
PROCEDURE TASK B:
(2) Sweep rate (Mv/S) = 20, 50 and 100 are used
(1) The electrochemical cell is connected to Autolab for discharge procedure
(3) Data generated from Autolab software is collected and graph of cell Current versus Vsce is plotted
CONCLUSION
In conclusion, metal is deposit on cathode during electrolysis. The electrons from anode are oxidized where zinc atoms to the cathode in which zinc ions are reduced. The action of oxidization and reduction occur together in oxidation-reduction reaction, which also called redox reaction. In redox reaction, zinc which loses electrons which is oxidized is called reducing agent while copper which gain electrons is the that causes oxidation is called oxidizing agent. To have balanced redox reaction, there must be at least one reduction and one oxidation.
PRINCIPLE
Electrical current is used in electroplating to coat the electrode in which two electrodes from different types of metal are used
Both of the electrodes are immersed in a solution that contains an electrolyte
The current flows in and out through two conducting electrodes which are anode and cathode respectively
The metal is plated to anode and then connected to an external supply of direct current.
Anode is oxidized when the power supply supplies direct current to it. This will make the metal atoms dissolve in the electrolyte solution and dissolved metal ions are reduced at the cathode.
Coating is formed
DISCUSSION
In this experiment, two electrodes which are zinc and copper are put into an electrolyte solution of ZnSO4. After 30 minutes of electroplating, a white coating appears on the copper electrode which is cathode, and after a few minutes, the copper electrode has zinc plating on it. By connecting the negative lead to the copper electrode supplies electrons to the copper electrode while Zn2t ions in solution near the copper gain electrons. Zinc ions are reduced at the cathode and become neutral zinc atoms. Neutral zinc atoms oxidized in the anode and becomes Zn2t ions. The cyclic voltammetric can also be used to measured current (A) and voltage (Volt) as it flows. Based on the generated value of current and voltage, a graph which indicate oxidization and reduction could be plot to show the reaction of reduction and oxidation.