(a)
Write balanced half-reactions for the process:
Oxidation: Se^2- (aq) → Se
(s) + 2e-
Reduction: 2So3^2- (aq) + 3H2O (l) + 4e- →
S2O3^2- + 6OH- (aq)
(b)
If E sulfite is 0.57 V, calculate E selenium:
E anode = E cathode – E cell
= -0.57 – 0.35
=
-.092
Answer:
Lower the pH slightly
Explanation:
A buffer is defined as the mixture between weak acid and conjugate base. In the problem, acetic acid is the weak acid and sodium acetate the conjugate base.
When a strong acid as perchloric acid is added to a buffer, <em>the pH decreases slightly</em> because the acid reacts with conjugate base producing weak acid and not affecting directly the concentration of H⁺ ions.
Se - 78
Selenium - 78
or
78/34 Se2-
