Page 36 - Spotlight A+ Form 4 & 5 Chemistry KSSM

Form
5
Chapter 1 Redox Equilibrium Chemistry
+
CHAP. 13. Based on Figure 1.17, the sodium ions, Na from move to zinc sulphate, ZnSO solution which CHAP.
4
1 the salt bridge move to copper(II) sulphate, has more positive charge. 1
CuSO solution which is lack of positive charge 14. Therefore, the solutions in both half-cells are
4
whereas sulphate ions, SO from the salt bridge maintained in a neutral state and the voltaic cell
2−
4
continues to function well.

1.2
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Aim: 2. A porous pot is filled with zinc sulphate, ZnSO
4
To determine the voltage produced from two solution until it is two-third full.
different pairs of metals in a chemical cell. 3. A zinc, Zn plate is dipped into zinc sulphate,
ZnSO solution.
4
Problem statement: 4. A beaker is filled with copper(II) sulphate,
How do different pairs of metals in chemical cells CuSO solution until it is half full.
4
affect the voltage produced? 5. The copper, Cu plate is dipped into copper(II)
sulphate, CuSO solution.
4
Hypothesis: 6. The porous pot is placed into the beaker.
Pair of metals with greater difference of standard 7. The circuit is completed by connecting the
electrode potential value will produce greater metals to a voltmeter as shown in Figure 1.18.
voltage.
Voltmeter
Variables: V
(a) Manipulated: Different pairs of metals
(b) Responding: Voltage reading of the cell
(c) Fixed: Copper, Cu electrode, volume and Copper, Zinc,
Cu plate Zn plate
concentration of electrolytes
Copper(II) Porous pot
Materials:
sulphate, that contains
Copper, Cu plate, iron, Fe nail, zinc, Zn plate, CuSO solution zinc sulphate,
magnesium, Mg ribbon, sandpaper, 1.0 mol dm 4 ZnSO solution
-3
-3
iron(II) sulphate, Fe SO solution, 1.0 mol dm 4
2 4 Figure 1.18
copper(II) sulphate, CuSO solution, 1.0 mol
4
-3
dm zinc sulphate, ZnSO solution, 1.0 mol dm 8. The reading of the voltmeter is recorded.
-3
4
magnesium sulphate, MgSO solution 9. Steps 2 to 8 are repeated by replacing zinc, Zn
4
plate and zinc sulphate, ZnSO solution in the
4
Apparatus: porous pot with;
Voltmeter, 250 cm beaker, connecting wires with (a) iron nail and iron(II) sulphate, FeSO
3
4
crocodile clips, porous pot solution.
(b) magnesium, Mg ribbon and magnesium
Procedure: sulphate, MgSO solution.
4
1. All metal plates are cleaned with sandpaper.
Result:
Table 1.11
Set Pair of metals Voltage (V) Observations at the electrodes
I Zinc, Zn plate + 1.1 Zinc, Zn plate becomes thinner.
copper, Cu plate Brown solid is deposited on the copper, Cu plate.
II Iron, Fe nail + 0.7 Iron, Fe nail becomes thinner.
copper, Cu plate Brown solid is deposited on the copper, Cu plate.
III Magnesium, Mg ribbon + 2.7 Magnesium, Mg ribbon becomes thinner.
copper, Cu plate Brown solid is deposited on the copper, Cu plate.

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