A-Level CIE Chemistry 5.4 Electrode Potentials & Electrochemical Cells (A Level only): 4 (a) (i) Define the term standa

4 (a) (i) Define the term standard cell potential, $E^{ ext{o}}_{cell}$ - CIE - A-Level Chemistry - Question 4 - 2016 - Paper 1

Question 4

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4 (a) (i) Define the term standard cell potential, $E^{ ext{o}}_{cell}$. Standard cell potential, $E^{ ext{o}}_{cell}$, is the electromotive force (EMF) or potentia... show full transcript

Worked Solution & Example Answer:4 (a) (i) Define the term standard cell potential, $E^{ ext{o}}_{cell}$ - CIE - A-Level Chemistry - Question 4 - 2016 - Paper 1

Step 1

Define the term standard cell potential, $E^{ ext{o}}_{cell}$

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Answer

Standard cell potential, $E^{ ext{o}}_{cell}$ , refers to the electromotive force (EMF) or potential difference between two electrodes (or half cells) under standard conditions (temperature of 298 K and concentration of 1 mol dm $^{-3}$ ).

Step 2

Complete the diagram, labelling the components you add

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Answer

The components to be added are a voltmeter and a salt bridge.

Step 3

Identify the components A-D

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Answer

A. Ag $^{+}$ (aq) B. Ag (s) C. Pt (s) D. Fe $^{2+}$ (aq) and Fe (s)

Step 4

Use $E^{ ext{o}}$ values to write an equation for the cell reaction that takes place if the two electrodes in (a) are connected by a wire and the circuit is completed

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Answer

The cell reaction can be represented as:
Ag $^{+}$ (aq) + Fe (s) → Ag (s) + Fe $^{2+}$ (aq)

Step 5

Another electrochemical cell was set up using 0.31 mol dm$^{-3}$ Ag$^{+}$(aq) instead of the standard Ag solution

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Answer

Using the Nernst equation:
$E = E^{ ext{o}} + 0.059 ext{log}[Ag^+](aq)$
Substituting the given values:
$E = 0.80 - 0.03 = 0.77$ V
Thus, the new $E_{cell} = 0.77$ V.

4 (a) (i) Define the term standard cell potential, $E^{ ext{o}}_{cell}$ - CIE - A-Level Chemistry - Question 4 - 2016 - Paper 1

Worked Solution & Example Answer:4 (a) (i) Define the term standard cell potential, $E^{ ext{o}}_{cell}$ - CIE - A-Level Chemistry - Question 4 - 2016 - Paper 1

Define the term standard cell potential, $E^{ ext{o}}_{cell}$

Complete the diagram, labelling the components you add

Identify the components A-D

Use $E^{ ext{o}}$ values to write an equation for the cell reaction that takes place if the two electrodes in (a) are connected by a wire and the circuit is completed

Another electrochemical cell was set up using 0.31 mol dm$^{-3}$ Ag$^{+}$(aq) instead of the standard Ag solution

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