Sulfuric acid is a very strong acid that can act as an existing agent at high co

Question

Sulfuric acid is a very strong acid that can act as an existing agent at high concentrations (very low pH, or even negative pH values). Under standard conditions, sulfuric acid has a low reduction potential. SO_2^2 (aq) + 4H^+ (aq) + 2e^- SO_2 (g) + 2H_2 O(1), 0.20 V which means it cannot oxidize any of the helices F_2, Cl_2, Br_2, or I_2. If the H^- ion concentration increased, however, the driving force for the sulfuric acid reduction is also increased according to lessthanorequalto Chalteler's principle. Sulfuric acid cannot oxidize the fluoride or chloride actions, but it can oxidize bromide and iodide actions when there are enough H^+ ions present. The standard reduction potentials of the halogens are as follows: F_2 + 2e^- rightarrow 2F^+, +2.87 V Cl_2 + 2e^- rightarrow 2Cl^-, + 1.36 V Br_2 + 2e^- rightarrow 2Br^-, 1.07 V I_2 + 2e^- rightarrow 2I^-, +0.54 V The Nemst equation allows us to determine what nonstandard conditions allow the reaction to occur have a positive E value). The Nemst equation relates B nonstandard potential, E, to the standard potential, E^+, and the reaction quotient, Q, by E = E^2 - 2.303 RT/nF log Q where R = 8.314 J/(mol middot K). T is the Kelvin temperature, n is the number of moles of electrons transferred in the reaction, and F = 96, 485 C/mol e^-. At 74.0 degree C, what is the maximum value of the reaction quotient, Q, needed to produce a non-negative E value for the reaction SO_4^2- (aq) + 4H^+ (aq) + 2Be^- (aq) Br_2 (aq) + SO_2 (g) + 2H_2 O(l) In other words, what is Q when E = 0 at this temperature?

Explanation / Answer

SO4^2- (aq) + 4H+ (aq) + 2Br- (aq) <--> Br2 (aq) + SO2 (g) + 2H2O (l)

Eocell = Eo ( SO4^2- , H+ / SO2) - Eo( Br2 /Br-)

= 0.2 - 1.07

= -0.87

E cell = Eo cell - ( RT /nF) ln Q where n = number of electrons involved per reaction= 2

T = 74 C = 74 + 273 = 347 K

E cell = 0 , Eocell = -0.87 , we use al values and get Q

0 = -0.87 - ( 8.314 x 347 / 2 x 96485) ln Q

ln Q = -58.19

Q = exp ( -58.19)

= 5.3 x 10^ -26

Related Questions

Navigate

• Browse (All)
• Browse S
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.