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Chemical cells for SQA National 5 Chemistry

Chemical cells

This page covers the following topics:

1. Chemical cells
2. Electrochemical series

A chemical cell is a system that uses chemical reactions to create a potential difference across its electrodes. The voltage created at the cell is influenced by the the reactions happening in a cell and electrodes used. For example, the further away in the reactivity series a reduced metal is from the oxidised metal, the greater voltage is created.

Two separate redox reactions within solutions can be linked with a salt bridge to create a cell. The salt bridge completes the circuit by providing relevant ions to the solution it connects. Multiple cells can be combined to produce a battery that can have a higher potential difference across its electrodes. Once a non-rechargeable battery runs out of reactants in its cells, it cannot be reused by recharging, but it still may be recycled.

Chemical cells

Electrochemical series is a list of half equations and their corresponding electrode potentials. Standard electrode potential is the voltage that is created when a specific reduction or oxidation is occurring in comparison to hydrogen oxidation. The aforementioned potentials are usually measured for 1.00 mol/dmยณ ion solutions at standard room temperature and pressure. The greater the electrode potential, the more favourable a particular redox process is and the stronger oxidising agent the initial reactant is.

Electrochemical series

1

Two separate redox reactions within solutions can be linked with a salt bridge to create a cell. Explain the function of the salt bridge.

The salt bridge completes the circuit by providing relevant ions to the solution it connects.

completing the circuit by providing ions

Two separate redox reactions within solutions can be linked with a salt bridge to create a cell. Explain the function of the salt bridge.

2

Provide the conditions at which standard electrode values are given at.

Standard electrode potentials are usually measured for 1.00 mol/dmยณ ion solutions at standard room temperature and pressure.

1.00 mol/dmยณ concentration, room temperature and pressure

Provide the conditions at which standard electrode values are given at.

3

Name two main factors that affect the voltage created by a chemical cell.

The voltage created at the cell is influenced by the the reactions happening in a cell and electrodes used.

reactions, electrodes

Name two main factors that affect the voltage created by a chemical cell.

4

What is the relationship between the standard electrode potential and the reducing ability of a reactant involved in a corresponding equation?

The greater the electrode potential, the more favourable a particular redox process is and the stronger oxidising agent the initial reactant is. Thus, the greater the potential, the weaker the reducing ability of the reactant.

The greater the potential, the weaker the reducing ability.

What is the relationship between the standard electrode potential and the reducing ability of a reactant involved in a corresponding equation?

5

Describe a non-rechargeable battery.

Once a non-rechargeable battery runs out of reactants in its cells, it cannot be reused by recharging, but it still may be recycled.

A non-rechargeable battery cannot be reused after running out of reactants.

Describe a non-rechargeable battery.

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