Answer:
Option (A) 3.6 hours
Explanation:
Data obtained from the question include:
Current (I) = 22.2A
Time (t) =..?
Next, we shall determine the quantity of electricity needed to reduce 1 mole of Al^3+ to aluminium metal.
This is illustrated below below:
Al^3+ + 3e —> Al
From the above equation, 3 electrons are needed to reduce 1 mole of of Al^3+ to aluminium metal.
Recall:
1e = 1 Faraday = 96500C
Therefore, 3e = 3 x 96500C = 289500C.
Therefore, 289500C of electricity is needed to reduce 1 mole of Al^3+ to aluminium metal.
Next, we shall determine the time taken for 289500C of electricity to reduce 1 mole of Al^3+ to aluminium metal using a current of 22.2A. This can be achieved as follow:
Quantity of electricity (Q) = 289500C
Current (I) = 22.2A
Time (t) =..?
Q = it
289500 = 22.2 x t
Divide both side by 22.2
t = 289500/22.2
t = 13040.5 secs.
Finally, we shall convert 13040.5 secs to hours. This is illustrated below:
3600 s = 1 hr
Therefore, 13040.5 s = 13040.5/3600 = 3.6 hrs
Therefore, the time taken for the reaction is 3.6 hours
