3.1.11 Electrode potentials and electrochemical cells Flashcards
What is an electrochemical cell made of?
Two half-cells connected by a salt bridge.
What does a simple half-cell consist of?
A metal electrode in a solution containing a compound of that metal (e.g. Cu in CuSO₄).
What happens when two half-cells are connected in a circuit?
They produce a small voltage.
What is the function of the salt bridge in an electrochemical cell?
It allows ions to move and completes the circuit.
What is the salt bridge usually made from?
Filter paper soaked in a salt solution, usually potassium nitrate (KNO₃).
Why can’t a solution like potassium chloride be used in copper half-cells?
The salt should be unreactive with the electrodes and electrode solution.
The chloride ions would form complexes with the copper ions.
Why does a voltage form in an electrochemical cell?
Because one electrode (e.g. zinc) loses electrons more readily, creating a build-up of electrons and a potential difference.
More negative electrode potential = oxidised species
More positive electrode potential = reduced species
Why is a high resistance voltmeter used in measuring cell potential?
To ** ** flow, allowing measurement of the maximum potential difference (E).
