ch5: galvanic cells and fuel cells as sources of energy

Question 1

what is a galvanic cell

Answer 1

a galvanic cell/voltaic cell is a cell in which chemical energy is converted to electrical energy.

Question 2

what is the role of the salt bridge in a galvanic cell?

Answer 2

• the salt bridge also has ions that move to the half-cells. the cations move to the cathode (to balance the incoming electrons) and the anions move to the anode (to balance the leaving electrons).
• the salt bridge completes the circuit by allowing current to flow between the two half cells. the salt bridge is usually soaked in an unreactive electrolyte (such as KNO3)

Question 3

which half cell does reduction occur at?

Answer 3

the cathode

Question 4

which half cell does oxidation occur at?

Answer 4

the anode

Question 5

which way do electrons flow in a half cell?

Answer 5

from the anode to the cathode

Question 6

what sort of electrode is used if the conjugate redox pair in the cell is not a metal?

Answer 6

an inert/unreactive electrode such as platinum or graphite is used.

Question 7

what are the two types of galvanic cells and their differentiating characteristic

Answer 7

• primary cells (disposable)
• secondary cells (rechargeable)

Question 8

where are the strongest reductants and weakest oxidants located on the electrochemical series?

Answer 8

bottom

Question 9

where are the weakest reductants and strongest oxidants located on the electrochemical series?

Answer 9

top

Question 10

calculating standard electrode potential

Answer 10

E0(cell)=E0(cathode/higher)-E0(anode/lower)

Question 11

what is a fuel cell

Answer 11

a fuel cell is a type of galvanic cell that generates electricity from redox reactions.

Question 12

how to balance an acidic fuel cell

Answer 12

balance like normal

Question 13

how to balance an alkaline fuel cell

Answer 13

balance after the hydrogen step by adding that same amount of of OHs as hydrogens to both sides. combine OHs and H to get waters and then cancel.

Question 14

describe the efficiency of a fuel cell

Answer 14

fuel cells convert chemical energy directly into electrical energy, making them quite efficient. (they’re more efficient than a coal-fired power plant)

Question 15

what are the advantages of fuel cells?

Answer 15

• highly efficient (converts directly from chemical to electrical energy)
• fuel cells have a continuous output (given that fuel is supplied)

Question 16

what are the disadvantages of fuel cells?

Answer 16

• expensive
• requires constant fuel supply