Chapter 7 Flashcards
(16 cards)
Define oxidation and reduction in terms of electrons.
Oxidation is loss of electrons; reduction is gain of electrons.
What is a redox reaction?
A reaction where oxidation and reduction occur simultaneously.
Explain the oxidation state of an element in its elemental form.
Zero, because it is uncombined.
What is the oxidation state of oxygen in most compounds?
-2, except in peroxides where it is -1.
What is the oxidation state of hydrogen in most compounds?
+1, except in hydrides where it is -1.
How do you balance redox reactions using the half-equation method?
Write separate oxidation and reduction half-equations, balance atoms and charges, then combine.
Define standard electrode potential (E°).
The voltage measured under standard conditions when a half-cell is connected to the standard hydrogen electrode.
What does a positive E° value indicate?
A strong tendency to be reduced (good oxidizing agent).
What does a negative E° value indicate?
A tendency to be oxidized (good reducing agent).
Write the equation for the standard hydrogen electrode.
2H⁺ + 2e⁻ ⇌ H₂.
How do you calculate the emf of a cell?
emf = E°(cathode) – E°(anode).
What conditions define standard electrode potentials?
1 mol/dm³ concentration, 100 kPa pressure, 298 K temperature.
Explain why the electrode potential changes if conditions are not standard.
Concentration or temperature changes shift equilibrium and change voltage.
What is the role of the salt bridge in an electrochemical cell?
Maintains electrical neutrality by allowing ion flow.
Why is platinum used as an electrode in some half-cells?
It is inert and conducts electrons without reacting.
Explain how electrochemical cells produce electricity.
Redox reactions transfer electrons through an external circuit from anode to cathode.
