electrochemistry Flashcards
what is a salt bridge ?
a tube of unreactive ions that can move between the solutions to carry the flow of charge but won’t interfere with the reaction
how to represent a cell ?
most negative potential on the left
ROOR
reduced form, oxidised form, oxidised form, reduced form
always include state symbols
salt bridge shown by ||
what is the standard hydrogen electrode (SHE)
measuring standard for half-cell potentials
standard conditions for SHE
1moldm3 solution
temperature of 298K
100kPa
what does the SHE consist of
Hydrochloric acid
Hydrogen gas
Platinum electrode
why is a platinum electrode used for SHE
inert so won’t interfere with reaction
draw the SHE and label
check physics and maths tutor for answer
effect of increasing concentration on emf
emf more positive as fewer electrons are produced
effect of increasing pressure on emf
emf more negative as more electrons are produced
what does a lithium cell consist of
lithium cobalt oxide electrode
graphite electrode
lithium half cell equations and overall
(negative electrode)
Li <——-> Li+ + e-
(positive electrode)
e- + Li+ + CoO2 <———> Li+[CoO2]-
overall:
Li + Li+ + CoO2 <——-> Li+ + Li+[CoO2]-
how do you recharge a rechargeable cell ?
apply a current over the cell so electrons move in the opposite direction
reversing reaction
why are hydrogen fuel cells more environmentally friendly
water is the only waste product
