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A2 Chemistry Unit 2 > Electrode Potentials > Flashcards

Flashcards in Electrode Potentials Deck (28)
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1

When is dynamic equilibrium achieved

When the rate of ions leaving = rate they are joining

2

What are the conditions for a SHE

Platinum electrode
1 mol dm^-3 of hydrogen ions
H2 gas at 100kPa
Temperature of 298K (25°C)

3

How can you tell which goes on the left when comparing cells

Most negative goes on the left
Oxidation is on the left

4

What is the definition of emf

The potential difference measured when two half cells are connected

5

What is the definition of standard electrode potential

The potential difference measured when a half cell is connected to the standard hydrogen electrode under standard conditions

6

What does the standard electrode potential allow you to do

Compare position of equilibrium
More negative = left
More positive = right

7

How do you measure the emf of a cell

EMF = voltage on right - voltage on left
(Biggest number - smallest number)

8

How do you use the emf of a cell to predict if a reaction will occur

1. Write full equation for reaction
2. Split into two half equations
3. Add together the emf of the the two half equations
4. If Ecell is positive then the reaction is feasible

9

What direction do electrons flow

From negative electrode to positive
Where there are lots of electrons to little

10

What happens in a SHE

H2 flows over pours platinum
Equilibrium set up between H2 and H+ ions
Catalysed by platinum

11

What is the salt bridge in an SHE and what does it do

Glass tube filled with electrolyte
Ions complete the circuit and the ends are stoppered to stop mixing of salt bridge contents and beakers

12

What are 3 positives of Hydrogen fuel cells

Renewable
Silent
No pollution as the only product is water

13

What is a characteristic of primary cells

Single use and non rechargeable

14

What is the characteristic of secondary cells

Rechargeable so multiple use

15

What is the characteristic of fuel cells

They continually produce current if there is enough fuel

16

If there is an increase in E° values will the thing be a better reducing agent or oxidising agent

A better oxidising agent

17

Is the E° value is more negative will the agent be a better reducing or oxidising agent

Stronger reducing agent

18

How do you use E° to predict if a reaction will occur

1. Write full equation
2. Split into two half equations
3. Add together the E° for the two half equations
4. If Ecell is positive then the reaction is energetically feasible

19

What is are the oxidation and reduction reactions in a Zinc-carbon cell

See notes

20

What is the overall equation for a zinc-carbon cell (primary cell)

See notes

21

What are the oxidation and reduction reactions of a lithium ion cell (secondary cell)

See notes

22

What is the overall equation for the reaction of a lithium ion cell (secondary cell)

See notes

23

What is the use of graphite in a lithium ion cell

Support medium
Water would react with lithium

24

How is a lithium ion cell recharged

Ions move from positive to negative so reactions are reversed

25

What is the conventional cell representation of a lithium ion cell

See notes

26

What are the oxidation and reduction reactions for an alkaline hydrogen-oxygen fuel cell

See notes

27

What is the overall equation for the reaction of an alkaline hydrogen-oxygen fuel cell

See notes

28

What is the cell convention for an alkaline hydrogen-oxygen fuel cell

See notes