how long (in hours) would it take to apply a chromium plating 1.0x10-2 mm thick

Question

how long (in hours) would it take to apply a chromium plating 1.0x10-2 mm thick to a car bumper with a surface area of .25m^2 in an electrolytic cell carrying a current of 25.0 A?

10. Chromium plating is applied by electrolysis to objects suspended in a dichromate solution, according to the following (unbalanced) half-reaction: How long (in hours) would it take to apply a chromium plating 1.0 10 t mm thick to a car bumper with a surface area of 0.25 m in an electrolytic eell carrying a current of 25.0 A? (The density of chromium is 7.19 g/cm)

Explanation / Answer

volume of surface deposited = thickness*area

= 1*10^-2*10^-3*0.25

= 2.5*10^-6 m^3 = 2.5 Cm^3

mass of Cr deposited = volume* density

= 2.5*7.19

= 17.98 gram

   Cr2O7^2-(aq) + 12e- + 14H^+(aq) ----> 2Cr(s) + 7H2O(l)

farady first law

w = zit

w = (E/F)it

w = weight of Cr = 17.98 grams

i = current = 25 A

t = time = ? hr

E = equivalent mass of Cr = atomicweight / charge = 51.9961/6 = 8.7 gram/equiv

F = faradays constant = 96500 C

17.98 = (8.7/96500)*25*t

t = 7977.3 sec

= 7977.3/(60*60)

= 2.216 Hr

Related Questions

Navigate

• Browse (All)
• Browse H
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.