3.1 Redox and standard electrode potential

Question 1

What is the negative electrode called?

Answer 1

Anode

Question 2

What is the positive electrode called?

Answer 2

Cathode

Question 3

In Zn –> Zn2+ + 2e- and Cu –> Cu2+ + 2e- what way do the electrons flow and why?

Answer 3

From Zn to Cu as zinc has a higher density of electrons

Question 4

What are the functions of a salt bridge?

Answer 4

complete the circuit
Balance charge
allows ions to move

Question 5

What do arrows on the wire represent?

Answer 5

Current flowing from positive to negative

Question 6

What do arrows next to the wire represent?

Answer 6

e- flow from negative to positive

Question 7

What is the definition of E0?

Answer 7

The voltage of a half cell when measured against the standard hydrogen electrode under standard conditions

Question 8

What is the half equation for
Zn2+ + 2e- —> Zn E0=-0.76
Cu2+ + 2e- —> Cu E0=+0.34

Answer 8

Zn + Cu2+ —> Cu + Zn2+

Question 9

What is the definition of the standard hydrogen electrode?

Answer 9

The half cell all other half cells are measured against under standard conditions that are 298k, 1 atm, 1moldm-3 and 0.00V

Question 10

What is the standard hydrogen electrode equation?

Answer 10

2H+ + 2e- —> H2

Question 11

What is the electrode made from in the standard hydrogen electrode? Why?

Answer 11

Platinum as its inert

Question 12

What is required for the standard hydrogen electrode?

Answer 12

Hydrochloric acid
Hydrogen gas
Platinum electrode

Question 13

What is emf and how is it measured?

Answer 13

electromotive force
high resistance voltmeter

Question 14

Which electrode favours reduction?

Answer 14

Positive

Question 15

When are batteries rechargeable? how?

Answer 15

When the reaction is reversible
by adding a power source with a larger emf the electrons will be forced to revert backwards and reset

Question 16

What makes up a fuel cell?

Answer 16

two half-cells connected by a semi-permeable membrane
aqueous solution of sodium hydroxide

Question 17

What is the products of an oxygen-hydrogen fuel cell?

Answer 17

Water

Question 18

What are the advantages of an oxygen-hydrogen fuel cell?

Answer 18

Only water as a by product
more efficient than combustion cell

Question 19

What are the disadvantages of an oxygen-hydrogen fuel cell?

Answer 19

Obtaining hydrogen gives of CO2
H2 is highly flammable as a gas and storing it was a liquid or solid is expensive
People will no buy hydrogen powered vehicles (danger and cost)
Fuel cells give off toxins in their manafactuing
Fuel cells have limited life span

Question 20

What is the trend of oxidising agents in the electrochemical series?

Answer 20

Increase in strength down table (increase as more positive)

Question 21

What is the trend of reducing agents in the electrochemical series?

Answer 21

Decrease in strength down the table (decrease as more positive)

Question 22

Does the oxidiser or the reducer displace?

Answer 22

The oxidiser