6.6.1 - Laboratory Activity : Constructing the electrochemical series based on the potential difference between two metals

Laboratory Activity 6.6.1: Constructing the electrochemical series based on the potential difference between two metals

Aim: To construct the electrochemical series based on potential differences between two metal in a simple cell
Problem statement: How can the electrochemical series be built from the potential differences between two metals in a simple cell?
Hypothesis: The electrochemical series can be built by measuring the potential differences between two metal in a simple cell.
Variable:

	»	Fixed variable : Concentration of electrolytes
	»	Manipulated variable : Metallic pair
	»	Responding variable : Cell voltage

Material: » Zinc plate » Iron nail » Aluminium plate » Magnesium strip » Copper plate » Silver strip » 1 mole dm-3 of copper(II) sulphate solution

Apparatus: » Beaker » Voltmeter » Sand paper » Crocodile clip » Connecting wires

Procedure:

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1. The copper and iron nails are cleaned with sand paper. 2. The simple voltaic cell between copper and magnesium is set up. 3. The voltage is recorded immediately. 4. The metals that act as positive and negative terminals are determined. 5. The experiment is repeated using different pairs of metal in turns.[Magnesium and copper pair, aluminium and copper pair, zinc and copper pair and silver and copper pair]

Results:

Metallic pair	Positive terminal	Negative terminal	Voltage
Fe/Cu	Copper	Iron	0.7
Mg/Cu	Copper	Magnesium	2.7
Al/Cu	Copper	Aluminium	2.0
Zn/Cu	Copper	Zinc	1.1
Ag/Cu	Silver	Copper	1.1

Analysis:

	►	Mg, Fe, Al and Zn are more reactive than copper because they formed the negative terminal while copper formed the positive terminal.
	►	Cu is more reactive than silver because it formed the negative terminal while silver formed the positive terminal.
	►	Based on the experimental results, part of the electrochemical series can be constructed as shown below.

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Metal pairs that further apart in the electrochemical series produce a higher voltage than metal pairs which are close to each other.
Conclusion:

	►	The electrochemical series can be constructed by using different pairs of metal in simple voltaic cell.
	►	The hypothesis is accepted.

↶ 6.6 The Electrochemical Series

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