calculate the strength of current required to deposit 1.2 gm of magnesium from molten mgcl2 in 1 hr

The half reaction occurring during deposition is:

Mg2+ + 2e- ----------> Mg(s)

So to produce 1 mole of Mg we need 2 moles of electrons,

1 mol of Mg = 24 g
Thus 1.2 g of Mg = (1.2/24) = 0.05 moles
Hence no. of moles of electrons required to deposit  = 0.05 x 2 = 0.1 moles

Qty. of electricity passed (Q) = moles of electrons passed x 96500
 = 0.1 x 96500 = 9650 C

I = Q/t
I = 9650/ 60 x 60 (converting 1 hr into seconds)
I = 9650/3600 = 2.68 A.
 

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