electrochemistry Flashcards
electrochemistry
what reaction is used to create a current in electrochemical cells
redox reactions
electrochemistry
when does a metal produce a voltage in an electrochemical cell
when a metal is dipped into a solution of its ions and is connected to another half cell
electrochemistry
how are electrons left behind on the metal strip
when metal atoms give up electrons and dissolve to form metal ions
Zn(s) → Zn2+(aq) + 2e-
electrochemistry
what may happen if the electrons remain on the surface
some of the metal ions may reform with the electrons to make their atoms
Zn2+(aq) +2e- →Zn(s)
electrochemistry
what increases the likelihood of atoms reforming in electrochemical cells
when there is an excess of electrons on the metal strip
electrochemistry
what creates a larger potential difference in an electrochemical cell
the greater tendency of metal atoms to produce ions as some atoms dissolve in solution faster than others
electrochemistry
what half cell would be the positive electrode
the half cell with the smaller build up of electrons on its surface of the metal strip
electrochemistry
what does emf measure and its equation
- the force that moves the electrons around the circuit
- E(cell) = E°(reductio) - E°(oxidation) or E°(cell) = E°(right) - E°(left)
electrochemistry
what increases emf
the greater difference in electrode potential
electrochemistry
what way do electrons flow in an electrochemical cell
from the half cell with the higher electron build up to the half cell with the lower electron build up
electrochemistry
what is the salt bridge used for
its used as a conductor so that the ions are free to move on the bridge and it keeps the cells electrically neutral
electrochemistry
what does a salt bridge usually contain
solution of potassium chloride or potassium nitride
electrochemistry
what causes the equilibrium to shift in a electrochemical cell
The movement of electrons from one half cell to another
electrochemistry
what happens when the concertation of electrons increases in one of the half cells
concerntration of electrons increases in half cell B
- the ions in cell B will bond with the new delocalised electrons to form its atoms
- this moves the equlibrium to the left in half cell A
- in half cell A this will cause more ions to be formed which would preodcue more elctrons in cell A
electrochemistry
why does hydrogens electrode potential 0
its 0 by definition as its what we compare everything else to
electrochemistry
state the meaning of the term elecrochemical series
metals are ordered by their electrode power in comparison to a H2/2H+ half cell
electrochemistry
whats the standard conditions for an electrochemical cell
1 mol dm-3
298K
100kPa (only affects half cells with gasses)
electrochemistry
why does a half cell have to be connected to another half cell to measure potential (E)
the potential (E) of a half cell cant be measureed directly
electrochemistry
define the term standard electrode potential
- E.m.f/ voltage/ potential difference of an electrochemical cell
- comprised of X(s)/X2+(aq) half cell with S.H.E
- 298K, 100kPa, 1 mol dm-3
electrochemistry
what does a more postitve E°/V value tell us
increasing oxidising power
electrochemistry
what does a more negative E°/V value tell us
increasing reducing power
