3.1 - Redox + standard electrode potential

Question 1

Oxidation

Answer 1

loss of electrons

Question 2

Reduction?

Answer 2

gain of electrons

Question 3

Oxidising agent?

Answer 3

Species that oxidises another species but is itself reduced

Question 4

Examples of oxidising agents?

Answer 4

Potassium Dichromate
Potassium Permangenate
Concentration Sulphuric acid

Question 5

What colour does Potassium Dichromate turn?

Answer 5

Orange to Green

Question 6

What colour does Potassium Permangenate turn?
KmnO4

Answer 6

Purple to colourless

Question 7

What is the strongest oxidising agent?

Answer 7

Fluorine

Question 8

What is a reducing agent?

Answer 8

Reduces another species but itself oxidised

Question 9

Examples of Reducing agent?

Answer 9

Sodium Tetrahydridoborate(III)
Lithium tetrahydridoaluminate(III)
Sodium and ethanol

Question 10

Sodium Tetrahydridoborate(III)?

Answer 10

NABH4

Question 11

Lithium tetrahydridoaluminate(III)

Answer 11

LIAlH4
must be dissolved in ethoxyethane
anhydrous conditions
no water

Question 12

Sodium and ethanol?

Answer 12

Na+C2H5OH

Question 13

Diagram of a cell

Question 14

What are the standard conditions?

Answer 14

25 degrees / 298K
1 atm/1.01x10^5
conc of 1 moldm-3

Question 15

what is the equation of Copper?

Answer 15

Cu2+ + 2e- —– Cu(s)
EMF = 0.34 V

Question 16

what is the equation of zinc?

Answer 16

Zn2+ + 2e- —– Zn(s)
EMF = 0.76V

Question 17

Example of oxidation?

Answer 17

Zn(s)—- Zn2+(aq) + 2e-

Question 18

What does faesibility mean?

Answer 18

possibility

Question 19

How do you know if its faesible?

Answer 19

if it is positive

Question 20

Cu2++2e- + Zn(s) —- Cu(s) + ZN2+ + 2e-

Answer 20

Cu2+ + Zn(s) —- Cu(s) + ZN2+(aq)

Question 21

What is SO42- ( big 4 little -2) in this reaction?

Answer 21

a spectator ion

Question 22

what is a celldiagram?

Answer 22

is a short hand picture of the diagram of the cell

Question 23

what is the cell diagram?

Question 24

What is the standard hydrogen electrons used for?

Answer 24

to work out the EMF of the other half cells

Question 25

Equation for This

Answer 25

2H+ + 2e- ---- H2 E value= 0.00 as we dont want it to affect the others by all means

Question 26

Equation

Answer 26

2H+ + 2E- ---- H2 Zn (S) ---- Zn2+ + 2e- 2H+ is the oxidising agent and Zn(s) is the reducing agent

Question 27

What is a redox reaction?

Answer 27

when both reduction and oxidation take place at the same time

Question 28

what in an example of a redox reaction?

Answer 28

in the oxidation of alcohol

Question 29

What is the reduction of a nitride?

Answer 29

C=N ( 3 equal lines)

Question 30

Example of the reduction of a carboxylic acid, an aldehyde + ketone?

Answer 30

reduction of a nitrobenzene

Question 31

How does the fuel cell work?

Answer 31

Fuel cells convert chemical energy stored in the fuel (hydrogen) into the electrical energy (H2---2H+2e-) These produce electrons which flow in external circuit Hydrogen is a more efficient at releasing energy than traditional fossil fuels The electrons are made of Platinum as it is inert Hydrogen is passed over at the platinum electrode where platinum acts as a catalyst

Question 32

what happens at the anode?

Answer 32

electrons are lost H2-2H+ + 2e- Oxidation takes place the hydrogen ions pass through a semi permeable membrane to reach the cathode

Question 33

what happens at the cathode?

Answer 33

electrons are gained and react with hydrogen ions + oxygen to form water

Question 34

What does catalyst means?

Answer 34

substance which lowers the activation energy and provides an alternative pathway for the reaction to proceed

Question 35

What are advantages?

Answer 35

Only produces water as a waste product (no Co2 emissions ) less energy is wasted as heat - more efficient Hydrogen gas can be produced by burning fossil fossil fuels Hydrogen is a renewable source of energy

Question 36

what are disadvantages?

Answer 36

Highly flammable + must be stored in a pressured tank which is expensive to produce Hydrogen as a fuel can only produced by traditional methods fuel cells operate at lower temperatures of 80 degrees but need a catalyst + all transition metals are expensive