20. Electrochemistry

If [Br^–] = 0.010 M and [Al³⁺] = 0.022 M, predict whether the following reaction would proceed spontaneously as written at 25ºC:

Al (s) + Br₂ (l) ⇌ Al³⁺ (aq) + Br^– (aq)

Standard Reduction Potentials

Al³⁺ (aq) + 3 e^– → Al (s)       E°_red = –1.66 V

Br₂ (l) + 2 e^– → Br^– (aq)     E°_red = +1.09 V

Determine [Fe²⁺] for the following galvanic cell at 25ºC if given [Sn²⁺] = 0.072 M, [Fe³⁺] = 0.0219 M, and [Sn⁴⁺] = 0.00345 M. 

Sn²⁺ (aq) + 2 Fe³⁺ (aq)  ⇌. Sn⁴⁺ (aq) + 2 Fe²⁺ (aq)     E_cell = + 0.68 V

Standard Reduction Potentials

Sn⁴⁺ (aq) + 2 e^–  →. Sn²⁺ (aq)      E°_red = + 0.151 V

Fe³⁺ (aq) + e^–  →  Fe²⁺ (aq)         E°_red = + 0.771 V

Consider the following voltaic cell:

(c) What is the change in the cell voltage when the ion concentrations in the cathode half-cell are increased by a factor of 10?

A voltaic cell utilizes the following reaction: Al1s2 + 3 Ag+1aq2 ¡ Al3+1aq2 + 3 Ag1s2 What is the effect on the cell emf of each of the following changes? (a) Water is added to the anode half-cell, diluting the solution.

A voltaic cell is constructed that uses the following reaction and operates at 298 K: Zn(s) + Ni²⁺(aq) → Zn²⁺(aq) + Ni(s) (b) What is the emf of this cell when [Ni²⁺] = 3.00 M and [Zn²⁺] = 0.100 M? (c) What is the emf of the cell when [Ni²⁺] = 0.200 M and [Zn²⁺] = 0.900 M?