Answer to Question #348472 in General Chemistry for Austine

Question

6. Give the balanced full reaction and calculate the E° for galvanic cells based on the

following reactions. Draw diagrams indicating; the anode, cathode, flow of electrons, salt bridge

(a) Zn

2+

(aq)+ 2e

-  Zn (s)

Pb

2+

(aq) + 2e

-  Pb(s)

(b) Cr2O7

- + 14H+ + 6e

-  2Cr

3+ + 7H2O

H2O2 + 2H+ + 2e

-  2H2O

Answer 1

a)

Zn²⁺ + 2 e^- = Zn

Pb²⁺ + 2 e^- = Pb

Full reaction: PbCl2 + Zn = ZnCl₂ + Pb

Anode: Zn => Zn²⁺ + 2e^-

Cathode: Pb²⁺ + 2e^- => Pb

b)

Cr₂O₇^- + 14H⁺ + 6 e^- = 2 Cr³⁺ + 7H₂O

H₂O₂ + 2H⁺ + 2 e^- = 2 H₂O

Full reaction: K2Cr2O7 + 3 H₂O₂ + 4 H₂SO₄ = Cr₂(SO₄)₃ + K₂SO₄ + 7H₂O + 3O₂