Redox (I and II) Flashcards
advantage of methanol fuel cell
methanol is renewable
disadvantage of methanol fuel cell
produces carbon dioxide
why might a reaction not occur if an E cell is positive?
activation energy is too high
why might a value for an E cell be wrong?
because reaction is not occurring under standard conditions
what is the colour change for KMnO4- and under what circumstances
when MnO4 is being reduced to Mn2+ (or acting as oxidising agent) —-> colour change is purple to colourless
When MnO4 is in the burette being used for titration—–> colour change is from colourless to purple
What happens if KMnO4 isn’t acidified with sulphuric acid
MnO4 would only be oxidised to MnO2 and a brown solution would appear
Why can’t HNO3 as an oxidising agent to acidify KMnO4
a smaller volume of MnO4 would be used
when talking about why a reaction can occur, what should you say?
calculate E cell value and see if it is positive or not
talk about whether a certain molecule will be able to donate or receive the electrons
Equations for acidic hydrogen fuel cell
+ve electrode: 0.5 O2 + 2H+ + 2 e——> h2o
-ve electrode: h2 gas makes 2 H+ and e-
Equation of alkaline hydrogen fuel cell
+ve electrode: 0.5 O2 + 2H+ + 2e- make h2o
-ve electrode: h2 gas + 2 OH makes 2 e-and 2h20
Equation linking Gibbs and E cell
Delta G= -nFEcell
Where n is moles and F is Faraday constant
definition of standard electrode potential
The potential difference measured when an electrode system is connected to the hydrogen electrode system, and standard conditions apply
what do the strongest reducing agents have?
the most negative E cell
advantages of hydrogen fuel cells
greater efficiency
less green house gases are produced
disadvantages of hydrogen fuel cells
hydrogen is explosive- hard to transport
hydrogen is flammable
hydrogen fuel cells are expensive
hydrogen often produced from fossil fuels which are finite
