1) Galvanized nails are iron nails that have been plated with zinc to prevent ru

Question

1) Galvanized nails are iron nails that have been plated with zinc to prevent rusting. The relevant reaction is

Zn2+(aq)+2e??Zn(s)

For a large batch of nails, a manufacturer needs to plate a total zinc mass of 2.50kg  on the surface to get adequate coverage.

How many moles of zinc are in 2.50kg  of zinc?

2)

The total charge of a mole of electrons is 96,500 coulombs (C) and

1ampere(A)=1coulomb/second(C/s)

Part A) What mass of Cu(s) is electroplated by running 21.0A of current through a Cu2+(aq) solution for 4.00 h?

Part B) How many minutes will it take to electroplate 56.1g of gold by running 5.00 A of current through a solution of Au+(aq)?

3) What mass of gold is produced when 6.90A  of current are passed through a gold solution for 10.0min ?

Explanation / Answer

1)

No.of moles = mass /molecular weight

Mass of Zn = 2.5 kg =2500 g

Molecular weight of Zn= 65.37 g/mole

No.of moles of Zn = 2500/65.37 moles = 38.24 moles

2)

Faradays law can be written as:

W = (I*t*A)/(n*F)

where:

W = weight of plated metal in grams.

I = current in coulombs per second.

t = time in seconds.

A = atomic weight of the metal in grams per mole.

n = valence of the dissolved metal in solution in equivalents per mole.

F = Faraday's constant in coulombs per equivalent. F = 96,485.309 coulombs/equivalent.

Part A

I= 21 A

t= 4*3600 s

Equation: Cu+2(aq) + 2e- gives Cu(s)

Atomic weight of Cu =63.546 g/mole

n = 2(according to the equation)

F = 96,485.309 C/equivalent

W = (I*t*A)/(n*F)

W= 99.581 g

therefore, 99.581 g of Cu is electroplated.

Part B

Equation: Au+(aq) + 1e- gives Au(s)

n=1

Atomic weight of Au(A)= 196.96 g/mole

I= 5 A

W= 56.1 g

F = 96,485.309 C/equivalent

t= ?

W = (I*t*A)/(n*F)

t= 5496.37 s =91.6 min

Therefore,time requires = 91.6 min

c)

Equation: Au+ + 1e- gives Au(s)

MAss of Au produced(W) = ?

I=6.9 A

t=10*60 s =600 s

A=196.96 g/mole

F = 96,485.309 C/equivalent

W = (I*t*A)/(n*F)

W= 8.451 g

Mass of Au produced = 8.451 g

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