Electrode potential and fuel cells

Seite 1

Half cell reaction are always written with the electrons on the left, this means that the forward reaction is always reduction and the backwards reaction is always oxidation.

metal/metal ion half cells with another metal/metal ion is set up as shown below:

The metal wire connecting the zinc and the copper allows electrons to move from the more negative electrode to the less negative electrode

The salt bridge allows ions to move from the the more posositive solution t the less positive solution

The high resistance voltmeter allows you to read the amount of volts

Standard electrode potential - the emf of a half cell compared to that of a standard hydrogen half cell under standard conditions

standard cell potential - the emf between two half cells making up a cell under standard conditions

emf- the potential difference in charge between 2 points in a circuit

A cell is made by connecting together 2 half cells. The standard cell potential is the difference between the standard electrode potentials of each half cell

Because hydrogen is a gas it has to be pumped into the solution and bubbled through the sulphuric acid. platinum wire and foil is used because it is a very unreactive metal so it does not take part in the reaction. The dilute sulfuric acid acts as a source of H+ ions.

Writing cell reaction

The half equation for the half cell with the most negative E reverses whenever it s an cell

Balance the number of electrons on each half cell

Use the 2 half equations to create a whole equation

Cancel out the electrons to give the overall cell reaction

To find the V of the Ecell take away the most negative from the he most positive

Feasibility of reactions

the for negative the E value