Redox is Cringe

Question 1

What is oxidation

Answer 1

Loss of electrons
Gain of oxygen
Loss of hydrogen

Question 2

What is reduction?

Answer 2

Gain of electrons
Loss of oxygen
Gain of hydrogen

Question 3

What happens when a rod of a metal is dipped into a solution of its ions?

Answer 3

An equilibrium is set up between the solid metal and aqueous metal ions

Question 4

What is a simple salt bridge made out of?

Answer 4

Filter paper soaked in a saturated solution of KNO3

Question 5

At which electrode does reduction take place?

Answer 5

Cathode

Question 6

At which electrode does oxidation take place?

Answer 6

Anode

Question 7

What is emf?

Answer 7

The standard electrode potential of a half cell connected to standard hydrogen electrode

Question 8

What does a positive potential mean?

Answer 8

Substances are more easily reduced and will gain electrons

Question 9

What does a negative potential mean?

Answer 9

Substances are more easily oxidised and will lose electrons to become more stable

Question 10

Why are salt bridges necessary ?

Answer 10

They complete the circuit allowing a flow of charge through ion movement. They also contain inert ions so they don’t react with the electrodes.

Question 11

What conditions are required to use the standard hydrogen electrode?

Answer 11

Temperature- 298K
Pressure - 100 kPa
[H+] - 1M

Question 12

When would you use a platinum electrode?

Answer 12

When both the oxidised and reduced forms of the metal are in aqueous solution.

Question 13

what is a fuel cell?

Answer 13

a fuel cell uses the energy from the reaction of a fuel with oxygen to create volatage

Question 14

why is necessary to use a high resistance voltmeter?

Answer 14

so that they don’t divert much current from the main circuit

Question 15

what does the positive electrode favour?

Answer 15

reductioj

Question 16

what does the negative electrode favour/

Answer 16

oxidation

Question 17

what does increasing the concentration of reactants do to the E cell value?

Answer 17

increase it and vice versa

Question 18

what is reason why a reaction won’t take place even if the E cell value is positive/

Answer 18

it may have a very high activation energy

Question 19

what does a negative E° value indicate?

Answer 19

the further the equilibrium lies to the left i.e. the more readily the metal loses electrons to form ions

Question 20

what does a more positive (or less negative) E° value mean/

Answer 20

the further the equilibrium lies to the right i.e. the less readily the metal loses electrons to form ions

Question 21

Give two advantages of using fuel cells compared with the combustion of petrol or diesel?

Answer 21

• less CO2 produced overall.

- greater efficiency

Question 22

Give an advantage of using methanol,rather than hydrogen in a fuel cell for use in cars?

Answer 22

Methanol is a liquid and is therefore easier to store and transport.

Question 23

What is the essential difference between a fuel cell and conventional electrochemical cell?

Answer 23

-a fuel cell produces electricity by the reaction of a fuel with oxygen

Question 24

State two ways that hydrogen might be stored as a fuel for use in cars?

Answer 24

• compressed as a gas

- adsorbed onto a solid

Question 25

Suggest why some scientists consider that using hydrogen as a fuel for cars uses up more energy than using petrol or diesel as the fuel?

Answer 25

-energy is required to produce the hydrogen