Electrochem Flashcards
In a standard cell representation, where does the most negative half cell go?
Half cell with most negative potential goes on the left
What is the standard hydrogen electrode used for?
Measuring the electrode potential of half cells
What is the cell potential of the standard hydrogen electrode?
0V
What are the standard conditions needed when measuring half cell potential with standard hydrogen electrode?
1.0 mol dm^3 solution of H+
298K
100kPa
What does the hydrogen electrode consists of?
HCl
Hydrogen gas
Platinum electrode
Why is a platinum electrode used in a half cell?
Metallic so conducts electricity but is also inert so wont react with acid
What is a salt bridge used for?
Transfer ions between solution
What factors can alter the electrode potential of a half cell?
Temp
Conc of ions
Pressure
In an electrode, what reaction occurs at the most negative electrode?
Oxidation
In an electrode, what reaction occurs at the most positive electrode?
Reduction
How do you calculate EMF?
Emf(R) – Emf(L)
In the electrochemical series, which half reaction contains the best oxidising agent and which contains the best reducing agent?
Oxidising - Most positive one
Reducing - most negative one
When combing the half equations for an electrode, which equation should you flip?
The most negative one
What are the standard conditions of an electrode?
1.0 mol dm^3 of each solution for each ion solution
298K
100kPa
What is the start of the standard cell representation for a hydrogen electrode>
Pt / H+(aq) / H2(g)//
What can standard electrode potentials be used for?
Determining the feasibility of a redox reaction
What is the value of the EMF is the reaction is feasible?
Positive
How will an increasew in conc affect emf?
Make it more positive
How will an increase in pressure affect emf?
Make it more negative
What are the 3 types of electrochemical cells?
Rechargeable
Non rechargeable
Fuel cells
What type of reaction occurs in a rechargeable cell?
Reversible
What do lithium ion cells consists of?
Lithium cobalt oxide electrode
Graphite electrode
Lithium salt in organic solvent
What reaction occurs at the negative electrode in a lithium ion cell
Li –> Li+ + e-
What reaction occurs at the positive electrode in a lithium ion cell?
e- + Li+ + CoO2 –> Li^+[CoO2]^-
How is a lithium ion cell recharged?
A current is applied over the cell to force the electrons in the other direction
What is a fuel cell?
An electrochemical cell that does not need recharging
What is required in a hydrogen fuel cell?
Continuous supply of hydrogen and oxygen to generate a continuous current
What reaction occurs at the anode (+) in the hydrogen fuel cell?
H2 + 2OH- —> 2H2O + 2e-
What reaction occurs at the cathode (-) in the hydrogen fuel cell?
O2 + 2H2O + 4e- —> 4OH-
Benefit of using a hydrogen fuel cell?
Produces water as a waste product so seen as environmentally friendly
Drawback of using hydrogen fuel cells?
Use highly flammable hydrogen
Expensive to produce
