Electrochemical Cells And Electrode Potentials Flashcards
What’s oxidation and reduction
Oxidation- loss of electrons
Reduction- gain of electrons
What reaction occur when Fe^/Fe half cell is joined to the Mg^/Mg half cell
X more positive E* so X will be reduced and Y will be oxidised
Why does a reaction occur
E* of X/ is more positive than E* of Y/Y
When can a molecule of D oxidise E / another molecule of itself
When the E* value of D > E* value of E
How do you identify the weakest oxidising agent
Species on the LHS with the most negative E* value
What are the essential properties of the separator
Non reactive
Porous
Allow ions to cross
What is the function of the carbon rod in a non rechargeable cell
Allows electrons to flow
Why might a non rechargeable cell leak after being used for a long time
Zinc is used up during the process
Why is ethanol considered a carbon fuel
CO2 released by combustion and fermentation is equal to that taken up in photosynthesis
Why are electrodes made by coating ceramic material than using actual rods (not cost)
Increase surface area
Suggest why the emf value of hydrogen octogenarian fuel cell operating in acidic conditions is exactly the same as that of the alkaline cell
Same overall equation
Suggest one reason why the cells can’t be electrically recharged
Reactions not reversible
Give one reason why the emf of the lead acid cell changes after several hours
Reagents are used up
Explain why voltage remains constant in the fuel cell
Conagsnt supply of fuel and oxygen
Concentration remain constant
Main advantage of fuel cell for electric cars apart from pollution
Hydrogen ant oxygen supplied continuously can be operated without stopping to recharge
