electrode potentials allery

Question 1

what is a half cell

Answer 1

• one of an electrochemical cell

Question 2

how can a half cell be constructed

Answer 2

• metal dipped in its ions, or platinum electrode with 2 aqueous ions

Question 3

why do we use platinum with the 2 aqueous ions?

Answer 3

• platinum is inert
• electrically conductive electrode

Question 4

what is an electrochemical cell

Answer 4

• created by joining 2 different half cells together

Question 5

what is an electrochemical cell made up of?

Answer 5

• wire
• voltmeter
• salt bridge

Question 6

what happens when we connect 2 half cells

Answer 6

• one side undergoes a reduction process
• other side undergoes an oxidation process
• redox reaction occurs essentially

Question 7

what is the voltmeter used for

Answer 7

• to measure the potential difference between the 2 half cells

Question 8

how do the electrons flow?

Answer 8

• from a more reactive metal to a less reactive one

Question 9

what happens when a half cell oxidises?

Answer 9

the electrode becomes thinner as more of the ion is produced to make the electrons

Question 10

what happens when a half cell reduces

Answer 10

the electrode will get thicker as ions receive the electrons and turn into copper

Question 11

whats the role of the salt bridge

Answer 11

• completes the circuit
• filter paper with saturated KNO3 solution
• ions flow through which balances the charges

Question 12

what is electrode potential

Answer 12

• how easily the half cell gives up electrons

Question 13

how do we write equations in electrochemical cells

Answer 13

• in the reduced form
• we always show the equations with reduction in the forward direction
• electrons on left side

Question 14

how can we determine which half cell is being reduced and oxidised

Answer 14

• look at electrode potential value
• found in data book

Question 15

what happens if a half cell has a negative electrode potential value

Answer 15

it undergoes oxidation

Question 16

what happens if a half cell has a positive electrode potential value

Answer 16

• it undergoes reduction

Question 17

acryonym NO PRoblem

Answer 17

• negative oxidation
• positive reduction

Question 18

what is the STANDARD HYDROGEN ELECTRODE

Answer 18

• used as a reference to measure standard electrode potential

Question 19

how do we setup the SHE

Answer 19

• temp at 298K
• pressure at 100kPa
• concentrations of ions at 1moldm-3

Question 20

what is the electrochemical series

Answer 20

• list of half cell reactions and their standard electrode potentials

Question 21

what does a positive value in the electrochemical series tell us

Answer 21

• is is a more powerful oxidising agent

Question 22

how do we calculate the standard cell potential

Answer 22

E. = E. reduced - E. oxidised

redox

Question 23

how and why do we use cell notation?

Answer 23

• standard way of representing cells in chemistry

Reduced form | oxidises form || oxidised form | Reduced form

Question 24

what does a double line in a cell notation show

Answer 24

salt bridge

Question 25

how do we setup cell notation

Answer 25

- most negative half cell potential goes to the left of the double line