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Redox II

Electrochemical cells, emf and cell diagrams

  • 3 things to know
  • Papers 1 and 3

Overview

Calculating the standard emf of a cell, which electrode is positive and where oxidation and reduction occur, the salt bridge, writing and reading conventional cell diagrams such as the zinc and copper cell, and assembling electrochemical cells to measure their voltage.

What you need to know

Answer each one before you reveal it.

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Numbers

How is the standard emf of a cell calculated from two standard electrode potentials?

Key term

In a conventional cell diagram, what does a single vertical line represent?

Key term

In a cell, which electrode is the positive electrode?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    How is the standard emf of a cell calculated from two standard electrode potentials?

    Model answer

    E°cell = E°(positive electrode) − E°(negative electrode).

  2. 2

    In a cell, which electrode is the positive electrode?

    Model answer

    The one with the more positive (less negative) standard electrode potential.

  3. 3

    At which electrode does oxidation occur?

    Model answer

    At the negative electrode.

  4. 4

    At which electrode does reduction occur?

    Model answer

    At the positive electrode.

  5. 5

    What is used to complete the circuit between two half-cells?

    Model answer

    A salt bridge.

  6. 6

    In a conventional cell diagram, what does a single vertical line represent?

    Model answer

    A phase boundary between different states, such as between a metal and its solution.

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AAtomisation turns each element into gaseous atoms.
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Anode means electrode where oxidation occurs.
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