electrode potentials

What is an electrode potential?

The ability of a half-cell to gain or lose electrons

Define standard electrode potential (E°)?

The electrode potential of a half-cell measured under standard conditions

What are standard conditions?

298 K

100 kPa

solutions at 1.00 mol dm⁻³

What is the standard hydrogen electrode?

A reference electrode with a potential of 0 V

What is a half-cell?

A system where oxidation or reduction occurs

Equation for cell potential?

E°cell = E°(reduction) − E°(oxidation)

When is a reaction feasible?

When E°cell is positive

Where do electrons flow?

From the more negative electrode to the more positive electrode

Where does oxidation occur?

At the negative electrode

Where does reduction occur?

At the positive electrode

What is an electrochemical cell?

A system that converts chemical energy into electrical energy

What is the function of a salt bridge?

To complete the circuit and allow ions to flow

What does a more positive E° value mean?

Greater tendency to be reduced

What happens to E° if a half equation is reversed?

The sign changes

Do you multiply E° values when balancing equations?

NO

What are the conditions of the standard hydrogen electrode?

Hydrogen gas at 100 kPa, 298 K, 1.00 mol dm⁻³ H⁺ ions, platinum electrode

Why is platinum used in the standard hydrogen electrode?

-inert

-conductor

What does a voltmeter measure in an electrochemical cell?

The potential difference between two half-cells

Why is a salt bridge needed?

To allow ions to flow and maintain electrical neutrality

What is a stronger oxidising agent?

A species with a more positive E° value

What is a stronger reducing agent?

A species with a more negative E° value

What does E° tell you about equilibrium position?

A more positive E°cell means equilibrium lies further to the right

Does a positive E°cell mean a fast reaction?

No, only that the reaction is feasible