Question

1)A standard galvanic cell is constructed in which a H⁺ | H₂ half cell acts as the cathode. Which of the following statements are correct?

Hint: Refer to a table of standard reduction potentials.

(Choose all that apply.)

a) H₂ is oxidized at the cathode.

b) The cathode reaction is 2H⁺ + 2e^- -> H₂

c) Mn²⁺|Mn could be the other standard half cell.

d) Fe³⁺|Fe²⁺ could be the other standard half cell.

e) In the external circuit, electrons flow from the other compartment to the H⁺|H₂ compartment.

2) A voltaic cell is constructed from a standard Mg²⁺|Mg half cell (E°_red = -2.370V) and a standard I₂|I^- half cell (E°_red = 0.535V).

The anode reaction is:

____(aq)(s)(l)(g)

+

____(aq)(s)(l)(g)

>

____(aq)(s)(l)(g)

+

____(aq)(s)(l)(g)

The cathode reaction is:

____(aq)(s)(l)(g)

+

____(aq)(s)(l)(g)

>

____(aq)(s)(l)(g)

+

____(aq)(s)(l)(g)

The spontaneous cell reaction is:

___(aq)(s)(l)(g)

+

____(aq)(s)(l)(g)

>

____(aq)(s)(l)(g)

+

____(aq)(s)(l)(g)

The cell voltage is ___ V.

Answer 1

Q1. Correct statements are :

(b) The cathode reaction is : 2 H⁺ + 2 e^- H₂

(c) Mn²⁺|Mn could be the other standard half cell.

(e) In the external circuit, electrons flow from the other compartment to the H⁺|H₂ compartment.

Q2.

The anode reaction is : Mg (s) Mg²⁺ (aq) + 2 e^-

The cathode reaction is : I₂ (s) + 2 e^- 2 I^- (aq)

The spontaneous cell reaction is : Mg (s) + I₂ (s) Mg²⁺ (aq) + 2 I^- (aq)

The cell voltage is : 2.905 V

Explanation

Q2. standard cell potential, E^o_cell = (E^o_red cathode) - (E^o_red anode)

E^o_cell = (0.535 V) - (-2.370 V)

E^o_cell = 0.535 V + 2.370 V

E^o_cell = 2.905 V