Question

I need this ASAP please

Electric-powered vehicles produce less air pollution than gasoline-powered vehicles. A Zinc-air battery can be used in electric vehicles because it is light weight and rechargeable. The battery can be uses water oxygen gas rom the are, a solid zinc electrode, and an electrolyte.

A) Write the balances half reactions that occur at at the anode and the cathode of the air-zinc battery

B) write a balanced new ionic equation that represents the overall reaction for the zinc-air battery. calculate the Ecell net.

c) determine the mass of oxygen from the air that would be required to produce a current of 1.5X 10^3 for 5.0min?

D) Identify and explain a quantitative disadvantage of replacing the zinc electrode with the lead electrode.

Answer 1

a)

the anode

Zn + 4OH⁻ → Zn(OH)₄²⁻ + 2e⁻ (E₀ = －1.25 V)

the chathode

1/2 O₂ + H₂O + 2e⁻ → 2OH⁻ (E₀ = 0.34 V pH＝11)

b)

The overall reaction, when balancing electorn charges and OH-

2Zn + O₂ → 2ZnO (E₀ = 1.59 V)

Enet = 1.59 V

c)

1.5*10^3 amp for t = 5 min

then

charge = current x time

Q = (1.5*10^3)(5*60) = 450000 C

According to F = 96500 C/mol

then

mol = 450000/96500 = 4.66321 mol of electorns are being transferred

2Zn + O₂ → 2ZnO (E₀ = 1.59 V)

2 moles are being transferred

therefore

4.66321/2 = 2.33 mol of Oxygen

mass = mol*MW = 2.33*32 = 74.56 g of O2

d)

the disadvantage of replacing Zinc and lead will change the potential

i.e.

the potential of LEad will not make a large voltage as the one of Zinc, therefore less E°cell will be expected, requiring more time or giving less charge with the same time