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You are given the copper strip, lead strip, iron strip, aluminium strip, magnesium strip and copper (II) sulphate solution. Referring to the statement above, plan a laboratory experiment to construct the electrochemical series of the potential differences using different pairs of metals. Your planning must include the following items:
(a) Problem statement(b) All variables involved(c) Statement of hypothesis(d) List of materials and apparatus(e) Experimental procedure(f) Tabulation of data
Answer:
Problem statement:
How can the electrochemical series be constructed based on the potential difference between two metal?
Variables: Manipulated variable: Pairs of metalResponding variable: Potential difference / Voltmeter reading Fixed variable: Concentration and volume of copper (II) sulphate
Statement of hypothesis
The further apart the metal in the electrochemical series, the greater is their potential difference
List of materials and apparatus:
Materials: Copper strip, lead strip, iron strip, aluminium strip, magnesium strip and copper (II) sulphate solution, sandpaperApparatus: Voltmeter, beaker, connecting wire
Experimental procedure:
1. Clean the metals with sandpaper2. Pour 50 cm3 of copper(II)sulphate solution into a beaker3. Dip the magnesium and copper strips into copper(II) sulphate solution4. Complete the circuit5. Record the potential difference / reading of voltemeter6. Determine the metals strips which become the negative / positive
terminal7. Repeat Step 1 – 6 by replacing pairs of magnesium/copper with
aluminium/copper, iron/copper and lead/copperTabulation of data
Pair of electrodes Potential difference (V) Negative/ positive terminalMg / CuAl / CuFe / CuPb / Cu
In a simple voltaic cell, when two different metals are dipped into an electrolyte, the metal which situated higher in the electrochemical series will donate electrons and become the negative terminal
H
HH
H
C C
H
O
C O H
Essay
(a) Alcohol R contains four carbon atoms and is able to show isomerism.Draw and name the structural formulae of two isomers of alcohol R.
[4 marks](b) Table 7 shows two structural formulae of carbon compounds of P and Q.
Carbon compound Structural formula
P
Q
Based on Table 7, compare carbon compounds P and Q. [6 marks]
Table 7