Answer:
The time required for the coating is 105 s
Explanation:
Zinc undergoes reduction reaction and absorbs two (2) electron ions.
The expression for the mass change at electrode [tex](m_{ch})[/tex] is given as :
[tex]\frac{m_{ch}}{M} ZF = It[/tex]
where;
M = molar mass
Z = ions charge at electrodes
F = Faraday's constant
I = current
A = area
t = time
also; [tex](m_{ch})[/tex] = [tex](Ad) \rho[/tex] ; replacing that into above equation; we have:
[tex]\frac{(Ad) \rho}{M} ZF = It[/tex] ---- equation (1)
where;
A = area
d = thickness
[tex]\rho[/tex] = density
From the above equation (1); The time required for coating can be calculated as;
[tex][ \frac{20 cm^2 *0.0025 cm*7.13g/cm^3}{65.38g/mol}*2 \frac{moles\ of \ electrons}{mole \ of \ Zn} * 9.65*10^4 \frac{C}{mole \ of \ electrons } ] = (20 A) t[/tex]
[tex]t = \frac{2100}{20}[/tex]
= 105 s