Exercises - Alkali Metals

Exercises

1. Determine the oxidation state for all elements in the following molecules:

(a)        H₂O

(b)       NaCl

(c)        H₂O₂

(d)       Fe₂O₃

(e)        MnO₄⁻

(f)         Cr₂O₇²⁻

(g)        SiH₄

2. Complete the reduction and oxidation equation and write the redox equation in the following examples:

(a) MnO₄⁻ + Fe²⁺+ ???? → Mn²⁺ + Fe³⁺+ ?????? under acidic conditions

(b) MnO₄⁻ + Br⁻ + OH⁻ → ??? + BrO₃⁻  under basic conditions

(c) Cr₂O₇²⁻ + Cu⁺ → Cu²⁺+ ??? under acidic conditions

(d) IO₃⁻ + I⁻ → I₂  under acidic conditions

3. Complete the equation and indicate the standard reduction potential E_red assuming both reac-tions partners are used in the same concentration.

(a) Br₂ + 2I⁻ → ???? E₀(Br₂∕Br⁻) = 1.07 V

E₀(I₂∕I⁻) = 0.54V

(b) Fe²⁺ + Ce⁴⁺ → ???? E₀(Ce⁴⁺∕Ce³⁺) = 1.61 V

E₀(Fe³⁺∕Fe²⁺) = 0.77 V

(c) Br₂ + Fe → ???? E₀(Br₂∕Br )=107V

E₀(Fe²⁺∕Fe) = −0.44 V

4. Calculate E for the following redox pair when Mn³⁺= 0.5 M and Mn²⁺ = 0.01 M [E₀(Mn³⁺/Mn²⁺) = 1.51 V] using the Nernst equation.