Question

Using data in Appendix E, calculate the standard emf for each of the following reactions:

(a) H₂(g) + F₂(g)→2H⁺(aq) + 2F^-(g)

(b) Cu²⁺(aq) + Ca(s)¡ →Cu(s) + Ca²⁺(aq)

(c) 3 Fe²⁺(aq)→Fe(aq) + 2Fe³⁺(aq)

(d) 2 ClO₃^-(aq) + 10 Br^-(aq) + 12 H⁺(aq)→Cl₂(g) + 5 Br₂(l) + 6 H₂O(g)

One Class Solution:-

(a)

H₂(g) →2H⁺(aq) +2e- , E^o = +0.0 V

F₂(g) +2e-→ + 2F^-(g), E^o = +2.87 V

E^o=2.87V

b)

Cu²⁺(aq) + 2e- →Cu(s) red. E^o=+0.337 V

Ca(s)→ 2e- + Ca²⁺(aq) oxid. E^o=-2.87 V

E^o=0.337- (-2.87)=3.207 V

c)

Fe²⁺(aq) +2e-→Fe(s) E^o=-0.440V

Fe²⁺(aq)→ e- + 2Fe³⁺(aq) 0.771 V

E^o= -0.440-0.771= -1.211V

(d) 2ClO₃^-(aq) + 10Br^-(aq) + 12 H⁺(aq)→ Cl₂(g) + 5Br₂(l) + 6 H₂O (l)

e)

2ClO₃^-(aq) +10e- + 12 H⁺(aq)→ Cl₂(g) + 6 H₂O (l), E^o=+1.47 V

10 Br^- (aq) → 5Br₂(l) +2e-, E^o=1.0655 V

E^o=1.47-1.0655=0.4045V