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Zinc is to be electroplated onto both sides of an iron sheet that is 20 cm2 as a galvanized sacrificial anode. It is desired to electroplate the zinc to a thickness of 0.025 mm. It is found that a current of 20 A produces a zinc coating of sufficient quality for galvanized iron. Determine the time required to produce the desired coating, assuming 100 % efficiency.

User Eviljack
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1 Answer

5 votes

Answer:

The time required for the coating is 105 s

Step-by-step explanation:

Zinc undergoes reduction reaction and absorbs two (2) electron ions.

The expression for the mass change at electrode
(m_(ch)) is given as :


(m_(ch))/(M) ZF = It

where;

M = molar mass

Z = ions charge at electrodes

F = Faraday's constant

I = current

A = area

t = time

also;
(m_(ch)) =
(Ad) \rho ; replacing that into above equation; we have:


((Ad) \rho)/(M) ZF = It ---- equation (1)

where;

A = area

d = thickness


\rho = density

From the above equation (1); The time required for coating can be calculated as;


[ (20 cm^2 *0.0025 cm*7.13g/cm^3)/(65.38g/mol)*2 (moles\ of \ electrons)/(mole \ of \ Zn) * 9.65*10^4 (C)/(mole \ of \ electrons ) ] = (20 A) t


t = (2100)/(20)

= 105 s

User Schanti Schul
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