Lab #07 Report sheet Glvanic Cells PDF

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Glvanic Cells Students' Name: Students' Id. No. :

Section No.:

Unknown number

9

A- Reduction Potentials of Several Redox Couples Check the correct metal and solution then enter the reduction potential of the following Redox couples below and fill the empty cells Redox Couple

Cu-Zn

Ecell (V) 1.100

Anode

Equation for Anode HalfReaction

Cathode

Equation for Cathode HalfReaction

Zn

Zn(s)=Zn2+ (aq)+2e-

Cu

Cu2+ +2e- =Cu

Cu-Mg

2.710

Mg

Mg=Fe2++2e-

Cu

Cu2+ +2e- =Cu

Cu-Fe

0.780

Fe

Fe = Fe2+ +2e-

Cu

Cu2+ +2e- =Cu

Mg

Mg =Mg2++2e-

Zn

Zn2+ +2e- =Zn

Mg

Mg = Mg2++2e-

Fe

Fe2+ +2e- =Fe

Zn

Zn = Zn2++2e-

Fe

Fe2+ +2e- = Fe

Zn-Mg Fe-Mg Zn-Fe

1.610 1.930 0.320

Answer the following Questions:

1- Write the balance equations for the six cell reactions. 1 2 3 4 5 6

Zn + Cu2+ = Zn2+ +Cu Mg+ Cu2+ = Mg2+ +Cu Fe + Cu2+ = Fe2+ +Cu Mg + Zn2+ = Mg2+ +Zn Mg + Fe2+ = Mg2+ + Fe Zn + Fe2+ = Zn2+ +Fe

2- what is the oxidizing agent in the Zn-Mg cell? (Zn )

3- Compare the sum of the Cu-Zn and Zn-Mg cell potentials with Cu-Mg cell potential. Explain Cu-Zn + Zn-Mg = 1.100 +1.610 = 2.710 // Cu-Mg=2.710 Same values

4- Compare the sum of the Zn-Fe and Zn-Mg cell potentials with Fe-Mg cell potential. Explain

Zn-Fe + Zn-Mg = Fe-Mg 0.320 + 1.610 = 1.930 5- Complete the table as follows: ---Use Ecell Measured (Value from table above), find Reduction potential (experimental): E(M 2+/M) = Ecell + (-0.79V), assuming Zn as anode. ---Calculate reduction potential (Theortical) using Nenest equation (32.7) and the standard reduction potential.

Redox Couple

Ecell (V)

Reduction Electrode

Reduction Potential (experimental)

Reduction Potential (Theoritical)

% Error

Cu-Zn

1.100

C2+/Cu

0.31

0.31

0.00

Zn-Fe

0.320

Fe2+/Fe

-0.47

-0.47

Zn-Zn

0

Zn2+/Zn

-0.79

-0.79

Zn-Mg

-1.610

Mg2+/Mg

-2.4

-2.4

Zn-Unknown

0.530

………….

-0.26

-0.26

6- Reduction potential of the unknown redox couple _________-0.26_____

0.00...