Electrodes

Question 1

Half cell

Answer 1

It is one half of a electrochemical cell. Can be constructed of a metal dipped into into metal ions or a platinum electrode with 2 aqueous ions

Question 2

Electrochemical cells

Answer 2

These are made to two half cells joined together by a voltmeter and salt bridge

Question 3

What is voltmeter

Answer 3

Voltmeter is used to measure the potential difference between two half cells
Also prevents electrons flowing

Question 4

Salt bridge

Answer 4

Made of KNO3
Allow movement of ions which balances the charge

Question 5

Why salt bridge is made of KNO3

Answer 5

Because KNO3 is unreactive and ions are free to move

Question 6

Direction of flow of electrons in electrochemical cell

Answer 6

Electrons move from more reactive to less reactive metal
From left to right always

Question 7

Why might current produced by cell fall to zero after sometime

Answer 7

All reactants are used up

Question 8

What happens once cell reactants are used up

Answer 8

Stop working or start to leak

Question 9

Why is Standard hydrogen electrode used?

Answer 9

To compare the potential of electrode of a half cell

Question 10

General set up for SHE

Answer 10

H2 gas is pumped in at pressure of 100KPa
Temperature of whole system 298K
Concentration of ions is 1 mol/dm3
Platinum should be used as electrode

Question 11

Which specie should be the closest to salt bridge

Answer 11

specie with highest oxidation state

Question 12

Cell representation of standard hydrogen half cell

Answer 12

Pt/H2/H+//
The standard hydrogen electrode is always on the left side

Question 13

Give an environmental advantage of using rechargeable cells

Answer 13

metal is reused

Question 14

what is the disadvantage of using rechargeable cell

Answer 14

uses electricity to recharge which can be produced by the burning of fossil fuels which release CO2

Question 15

what is an electrolyte

Answer 15

an electrolyte is a part of battery that acts as conductive pathway for the ions and allow ions to move from one electrode to another

Question 16

conventional cell representation of lithium ion battery

Answer 16

Li/Li+//Li+,CoO2/Li(CoO2)/Pt

Question 17

recharge battery equation

Answer 17

reverse positive right reduced
reverse discharging equation of positive right reduced

Question 18

why some batteries are single use battery

Answer 18

because the electrochemical reaction taking place in them is irreverseable

Question 19

Advantage of using fuel cells for energy instead of fossil fuels

Answer 19

Greater efficiency than burning hydrogen in combustion engine
less polluting as water is the only product

Question 20

Disadvantage of using fuel cell over fossil fuel cells

Answer 20

H2 is difficult to store
Fossil fuels are combusted to produce hydrogen which releases CO2

Question 21

Advantage of fossil fuels compared to other types of cells

Answer 21

Voltage is constant as fuel and oxygen supplied constantly so concentration of reactants remain constant

Question 22

Suggest the effect if any on the cell if the surface area of each platinum electrode is increased.

Answer 22

Unchanged

Question 23

Environmental advantage of using hydrogen fuel cell

Answer 23

Less pollution as water is the only product

Question 24

Why use of a hydrogen oxygen fuel cell might not be carbon neutral

Answer 24

CO2 produced as fossil fuels are used to generate electricity to generate hydrogen