Electrode potentials

Question 1

What reactions happen in an electrochemical cell

Answer 1

Redox

Question 2

Explain a Zn/Cu electrochemical cell

Answer 2

Zn = more -ve = gets oxidised 
Zn looses electrons forming Zn2+
Electrons travel around the external circuit to the Cu electrode 
Cu2+ = more +ve = get reduced
Cu gains 2 electrons to form Cu

Question 3

How do u measure the voltage in a electrochemical cell

Answer 3

Insert a voltmètre

Question 4

Why is pt used as electrodes

Answer 4

Inert

Conducts electricity

Question 5

What are the half equation for a Zn/Cu cell

Answer 5

Zn -> zn2+ + 2e-

Cu2+ + 2e -> Cu

Question 6

What is the equation for electrode potential

Answer 6

Electrode potential = reduced - oxidised

Question 7

Define standard electrode potential

Answer 7

The voltage measured under standard conditions connected to a standard h electrode

Question 8

What are standard conditions

Answer 8

289k
100kpa
Solutions all have a conc of 1.00 moldm-3

Question 9

What electrode potential do standard h electrodes have

Answer 9

0.0V

Question 10

What side are standard h electrodes always on

Answer 10

Left

Question 11

Which side of the cell does the reduces species go

Answer 11

Right

Question 12

Which side of the cell does the oxidised element go

Answer 12

Left

Question 13

What factors affect electrode potentials

Answer 13

Temp
Pressure
Conc
As they effect the position of eqm

Question 14

Why are standard conditions used

Answer 14

Always get the same value for electrode potentials

Can compare with different cells

Question 15

What electrode potentials do very reactive metals have and why

Answer 15

More negative

More readily looses electrons (gets oxidised)

Question 16

What wlectode potential do very reactive non metals have

Answer 16

More positive

More readily wants to gain electrons (gets reduced)

Question 17

When are productions about the electrode potentials wrong

Answer 17

Changing the conc or temp of solution
The rate of reaction may be so slow it looks like nothing is Happening
The reaction has a high activation energy

Question 18

What is the equation at the anode of a oxygen hydrogen fuel cell

Answer 18

H2 -> 2H+ + 2e-

Question 19

What is the half equation at the cathode for a oxygen hydrogen fuel cell

Answer 19

0.5O2 + 2H+ + 2e- -> H2O

Question 20

What is the structure between the anode and cathode in a hydrogen oxygen fuel cell

Answer 20

Polymer electrolyte membrane

Question 21

What is the fuel in a hydrogen oxygen fuel cell

Answer 21

H2

Question 22

What is the oxidant in the hydrogen oxygen fuel cell

Answer 22

O2

Question 23

What is the function of the polymer electrolyte membrane

Answer 23

Only permeable to H+

Forcing e- to travel around the circuit to the cathode

Question 24

What catalyst is used a hydrogen oxygen fuel cell

Answer 24

Pt

Question 25

What is the waste product of a hydrogen oxygen fuel cell

Answer 25

H2O

Question 26

Explain how a hydrogen oxygen fuel cell works

Answer 26

1. Anode = pt catalyst splits the H2 into protons and electrons
2. The polymer electrolyte membrane only allows h+ to pass to the cathode forcing e- around the external circuit to the cathode
3. An electric current is created by the flow of electrons in the external circuit
4. Cathode = o2 combines with h+ (from anode) and e- (from circuit) to make H2O

Question 27

What are the befits of fuel cells

Answer 27

More efficient than combustion = energy isn’t wasted as heat
Produce less pollution = only produce H2O not CO2

Question 28

What are the negatives of fuel cells

Answer 28

The production of them needs a toxic chemicals which needs to be disposed of

The toxic chemicals are vey flammable. So if there’s a fault it will catch fire

Question 29

What is the danger of using lithium in batteries

Answer 29

High reactive ans flammable

If there’s a fiant it will catch on fire