6 This question is about chemical cells.
A student investigated the voltage produced by different chemical cells.
Figure 9 shows the apparatus
Figure 9
This is the method used.
1. Use cobalt as electrode X.
2. Record the cell voltage.
3. Repeat steps 1 and 2 using different metals as electrode X
6-1 Suggest two control variables used in this investigation.
[2 marks]
ANSWER
Electrode size, power supply, electrolyte volume or amount, electrolyte concentration, and electrolyte temperature are variable that can be controlled or manipulated
Table 4 shows the student’s results.
Table 4
6-2 Write the six metals used for electrode X in order of reactivity.
Use Table 4.
Justify your order of reactivity.
[4 marks]
ANSWER
6-3 Which of the following pairs of metals would produce the greatest voltage when used as the electrodes in the cell?
Use Table 4.
[1 mark]
ANSWER
Magnesium and Tin
6-4 Hydrogen fuel cells can be used to power different forms of transport. Some diesel trains are being converted to run on hydrogen fuel cells.
A newspaper article referred to the converted trains as the new ‘steam trains’.
Suggest Why.
[1 mark]
ANSWER
In a fuel cell, hydrogen is oxidized to produce water. Water is released as a vapour/steam.
