1.9 electrode potentials and cells

Question 1

required practical

Question 2

what is an electrochemical cell made of?

Answer 2

2 different metals dipped in salt solutions of their own ions and connected by a wire (external circuit)
salt bridge
2 reactions- redox process

Question 3

whats a salt bridge?

Answer 3

eg strip of filter paper soaked in KNO3(aq).
allows ions to flow between half cells and balance out charges- completes the circuit

Question 4

what is the cell potential/ cell EMF

Answer 4

voltage between the 2 half-cells (electrons flow from most reactive metal to least.

Question 5

what is electrode potential?

Answer 5

how easily a metal is oxidised
the direction each reaction goes in depends on how easily a metal is oxidised

Question 6

what does a negative cell potential mean?

Answer 6

a metal thats easily oxidised

Question 7

what does a positive cell potential mean?

Answer 7

a metal thats harder to oxidise

Question 8

how do you write the conventional representation of cells (cell notation)

Answer 8

R/O//O/R
- more negative electrode potential on the left
- phase boundary if diff states, comma if same state
- // is the salt bridge
- pt electrode goes on the end

Question 9

how do you write half equations for electrodes?

Answer 9

look at conventional representation and write equation from that.
reduction happens at positive electrode and oxidation happens at negative electrode

Question 10

how do you calculate cell potential?

Answer 10

Ecell= E right- E left
should always be positive value as more negative value is being taken away from more positive

Question 11

what factors affect the electrode potential?

Answer 11

reversible so equilibrium position is affected by temp, pressure, conc
changing eq changes cell pot

Question 12

why do you use standard conditions when measuring electrode potential?

Answer 12

so you get the same value for electrode potentials and you can compare values for diff cells

Question 13

what is the standard hydrogen electrode?

Answer 13

way to measure electrode potential
hydrogen gas is bubbled through solution of aq H+ ions. Pt electrode used as a platform for redox reactions
Must use standard conditions

Question 14

what is the standard electrode potential of a half-cell?

Answer 14

voltage measured under standard conditions when half cell is connected to standard hydrogen electrode

Question 15

how do you measure standard electrode potential?

Answer 15

SHE is always on left despite other being more + or more -
SHE has an electrode pot of 0.00V
FINISH???