Question

A galvanic cell consists of a iron electrode in 1 M Fe(NO3)2 and a copper electrode in 1 M Cu(NO3)2. What is the equilibrium constant for this reaction at 25oC? Enter you answer with 2 significant digits, using the syntax of "1.0x10(22)" for "1.0x1022

What is the cell potential (emf, in V) of this cell at 25^oC?

Cu |Cu²⁺ (0.0510 M) ‖ Br₂ |Br^- (0.363 M)

What mass (in g) of aluminum can be electroplated when 0.855 amps are used for 1.029 hours using a solution of aluminum nitrate?

What mass (in g) of silver can be electroplated when 0.781 amps are used for 1.281 hours using a solution of silver nitrate?

Answer 1

A) IRON ELECTRODE IS ANODE AND COPPER ELECTRODE IS CATHODE FROM THEIR REDUCTION POTENTIALS VALUES)

THE FREE ENERGY OF THE CELL SYSTEM AT 25oC , G = -nFE^o

OR = -2.303RT logKc

SO EQUATING THE BOTH, -2.303RT logKc = -nFE^o

E^ocell = E^o copper- E^o iron ( IRON IS ANODE AND COPPER IS CATHODE FROM THEIR REDUCTION POTENTIALS VALUES)

= +0.34 - (-0.44)

= +0.78 v

NUMBER OF ELECTRONS PARTICIPATING IN THE REDOX PROCESS,n = 2

1 FARADAY = 96500 CLOUMBS

Kc= EQUILIBRIUM CONSTANT =?

   2.303RT logKc = nFE^o

= 2 X 96500 X +0.78 v

T = 25 =273 = 298K

GAS CONSTANT = 8.314J/K.MOL

logKc =  2 X 96500 X 0.78 v/2.303X8.314J/K.MOLX 298K

= 26.4

Kc = ANTILOG (26.4)

= 2.5 X 10 ²⁶

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----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- THE LAST TWO ARE TO BE SOLVED BY FIRST LAW OF FARADAY'S LAWS OF ELECTROLYSIS

ELECTROCHEMICAL EQUIVALENT OF ALUMINIUM = ATOMIC MASS OF AL / VALENCY X 96500 CLOUMBS

= 27g/MOL/3 X 96500

= 9.33X 10^-5grequiv/C

QUANTITY OF CURRENT USED = 0.855 amp X 1.029 X 3600 seconds

= 3167.26 COLOUMBS

MASS OF ALUMINIUM DEPOSITED ,m

= ELECTROCHEMICAL EQUIVALENT OF Al X QUANTITY OF CURRENT IN CLOUMBS

= 9.33X 10^-5 X 3167.26

= 0.2955 GRAMS

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ELECTROCHEMICAL EQUIVALENT OF SILVER = ATOMIC MASS OF Ag / VALENCY X 96500 CLOUMBS

= 108g/MOL/1 X 96500

= 0.001119grequiv/C

QUANTITY OF CURRENT USED = 0.781 amp X 1.0281 X 3600 seconds

= 2890.605 COLOUMBS

MASS OF ALUMINIUM DEPOSITED ,m

= ELECTROCHEMICAL EQUIVALENT OF Al X QUANTITY OF CURRENT IN CLOUMBS

= 0.001119grequiv/CX 2890.605 COLOUMBS

=3.2346 GRAMS