Question

a. Use standard cell potentials to show what reaction would occur if you placed a strip of Cr in a solution of equal concentrations of NiCl2 and Al(NO3)3.

b. Zinc is plated onto iron to protect the iron from corrosion in a process called galvanization. How long would it take to plate 100g of zinc onto “sheet metal” in a ZnCl2 bath running at a current of 7.5A?

Promise to rate! Much appreciated, thank you!

Answer 1

a. Use standard cell potentials to show what reaction would occur if you placed a strip of Cr in a solution of equal concentrations of NiCl2 and Al(NO3)3.

Solution :-

The reduction potential of the metals are as follows

Cr = -0.74 V

Al^3+= -1.66 V

Ni^2+ = -0.25 V

When the reduction potential is more negative then it can reduce the other element

So the

Cr can reduce the Ni^2+ but it cannot reduce the Al^3+

So the reaction which occur is as follows

2Cr(s) + NiCl2 ----- > 2CrCl3(aq) + 3 Ni(s)

b. Zinc is plated onto iron to protect the iron from corrosion in a process called galvanization. How long would it take to plate 100g of zinc onto “sheet metal” in a ZnCl2 bath running at a current of 7.5A?

Solution :-

Lets calculate the moles of Zn

Moles of Zn = 100 g / 65.38 g per mol

                     = 1.5295 mol Zn

Moles of electrons = 1.5295 mol Zn * 2 mol e- / 1 mol Zn = 3.185 mol electron

Now lets find the charge

Charge = 3.185 mole- * 96500 C / 1 mol e-

        = 307353 C

Now lets find the time in second

Charge = current * time

Charge / current = time

307353 C / 7.5 A = 40980 s

Now lets convert second to minute and hour

40980 s * 1min / 60 sec = 683 min

683 min * 1 hr / 60 min = 11.38 hr