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Worksheet: Calculating Cell Potentials from Reduction Potentials

Q1:

A galvanic cell consists of a M g electrode in 1 M  M g ( N O ) 3 2 solution and a A g electrode in 1 M  A g N O 3 solution. What is the standard cell potential?

Half-equation M g ( ) + 2 e M g ( ) 2 + – a q s A g ( ) + e A g ( ) + – a q s
Standard electrode potential, 𝐸 ⦡ (V) βˆ’ 2 . 3 7 2 + 0 . 7 9 9 6

Q2:

Using the standard electrode potentials shown in the table, determine which of the following metals are capable of reducing L a O 2 3 to L a metal.

Half-equation C a ( ) + 2 e C a ( ) 2 + – a q s A l ( ) + 3 e A l ( ) 3 + – a q s F e ( ) + 2 e F e ( ) 2 + – a q s L a ( ) + 3 e L a ( ) 3 + – a q s
Standard electrode potential, 𝐸 ⦡ ( V ) βˆ’ 2 . 8 6 8 βˆ’ 1 . 6 6 2 βˆ’ 0 . 4 4 7 βˆ’ 2 . 5 2
  • A F e only
  • B A l only
  • C A l and F e
  • D C a only
  • E C a and A l

Q3:

The standard reduction potentials for oxygen gas and two cobalt(III) complexes are shown below:

Half-equation O ( ) + 4 H ( ) + 4 e 2 H O ( ) 2 + – 2 g a q l [ C o ( H O ) ] ( ) + e [ C o ( H O ) ] ( ) 2 6 3 + – 2 6 2 + a q a q [ C o ( N H ) ] ( ) + e [ C o ( N H ) ] ( ) 3 6 3 + – 3 6 2 + a q a q
Standard electrode potential, 𝐸 ⦡ ( V ) +1.229 +1.8 +0.1

Based on the cell potentials, which of the two complexes, [ C o ( H O ) ] 2 6 2 + and [ C o ( N H ) ] 3 6 2 + , can be oxidized to the corresponding cobalt(III) complex by oxygen? Assume that all reactions take place under standard conditions.

  • ANeither [ C o ( H O ) ] 2 6 2 + nor [ C o ( N H ) ] 3 6 2 +
  • B [ C o ( H O ) ] 2 6 2 + but not [ C o ( N H ) ] 3 6 2 +
  • C [ C o ( N H ) ] 3 6 2 + and [ C o ( H O ) ] 2 6 2 +
  • D [ C o ( N H ) ] 3 6 2 + but not [ C o ( H O ) ] 2 6 2 +
  • EMore information is needed.

Q4:

Using the standard electrode potentials shown in the table, calculate to 3 decimal places the cell potential for the electrochemical cell:

Half-equation C d ( ) + 2 e C d ( ) 2 + – a q s N i ( ) + 2 e N i ( ) 2 + – a q s
Standard electrode potential, 𝐸 ⦡ ( V ) βˆ’ 0 . 4 0 3 0 βˆ’ 0 . 2 5 7
  • A 0.125 V
  • B 0.146 V
  • C 0.155 V
  • D 0.167 V
  • E 0.164 V

Q5:

Using the standard electrode potentials in the table below, calculate the standard cell potential for a galvanic cell with the overall reaction:

Half-equation S n ( ) + 2 e S n ( ) 2 + – a q s C u ( ) + e C u ( ) 2 + – + a q a q
Standard electrode potential, 𝐸 ⦡ (V) βˆ’ 0 . 1 3 7 5 + 0 . 1 5 3

Q6:

What is the standard electrode potential for the galvanic cell with the following overall reaction?

Half-equation A g ( ) + e A g ( ) + – a q s F e ( ) + 2 e F e ( ) 2 + – a q s
Standard electrode potential, 𝐸 ⦡ (V) + 0 . 7 9 9 6 βˆ’ 0 . 4 4 7

Q7:

Using the standard electrode potentials in the table below, calculate the standard cell potential for a galvanic cell consisting of A u 3 + / A u and N i 2 + / N i half-cells.

Half-equation A u ( ) + 3 e A u ( ) 3 + – a q s N i ( ) + 2 e N i ( ) + – a q s
Standard electrode potential, 𝐸 ⦡ (V) + 1 . 4 9 8 βˆ’ 0 . 2 5 7
  • A βˆ’ 1 . 7 5 5 V
  • B 1.241 V
  • C βˆ’ 1 . 2 4 1 V
  • D 1.755 V