Electrochemistry Flashcards
What happens at anode and cathode
Oxidation at anode and reduction at cation
What does a salt bridge do?
keep charges balanced
EMF stand for
electromotive force - potential difference between C&A
What is cell potential
value affected by temperature, concentration and pressure
How do you make measurements?
impossible to measure potential of a single electrode
measure potential difference
Why is platinum used
provides a surface for the reaction
What is hydrogen used for?
standard and reference electrode
Whats standard electrode potential
emf of a half cell compared with a H half cell at standard conditions
What is electrode potentiaal
ability to gain or lose electrons
more positive the potential…
greater tendency to gain electrons so more powerful oxidising agent
What does the higher potential do?
oxidises the lower oneq
How do you determine cell potential?
Half equations, full equation (switch lower value)
Identify positive terminal
Cell potential
explanation
Whats the explanation for cell potential
more -/= moves right/left due to red/ox
Eq with more negative moves left
Eq with more positive moves right
Whats the limitations of prediciations
cant tell how fast a feasible eraction is so some may not take place
not standard conditions
only aqueous solutions
emf>0.4v its valid
Storage and fuel cells are…
rechargeable, non rechargeable, fuel cells
Lead storage battery
PbO2 +Pb +4H+ –> 2PbSO4 +2 water
Portable but expensive
What are fuel cells
two electrodes separated by electrolyte, particles move between them
catalysts used
electricity is generated when oxygen and hydrogen combine
Describe the root of a fuel cell
Hydrogen enters, loses an electron, travel via external circuit, H+ through electrolyte, oxygen enters and then gains an electron
Advantages of fuel cells
clean, quick, abundant, efficient, less pollution
Disadvantages of fuel cells
expensive, not durable hard to store, starting time slow, transport
