What ph is needed to produce this value of q if the concentrations and pressures

Question

What ph is needed to produce this value of q if the concentrations and pressures are:

Sulfuric acid is a very strong acid that can act as an oxidizing agent at high concentrations (very low pH, or even negative pH values). Under standard conditions, sulfuric acid has a low reduction potential, SO4 -(aq) + 4H+ 2e so2(g) +2H2(1) +0.20 v which means it cannot oxidize any of the halides F2, CI2. Br2, or I2. If the H+ ion concentration is increased, however, the driving force for the sulfuric acid reduction is also increased according to Le Chatelier's principle. Sulfuric acid cannot oxidize the fluoride or chloride anions, but it can oxidize bromide and iodide anions when there are enough H+ ions present. The standard reduction potentials of the halogens are as follows: F2+ 2e- rightarrow 2F ,+2.87 v CI2 +2e rightarrow 2CI,+1.36 v Br2 +2e rightarrow 2Br ,+1.07 I2+2e rightarrow ,2I +0.54 v The Nernst equation allows us to determine what nonstandard conditions allow the reaction to occur (have a positive E value). The Nernst equation relates a nonstandard potential, E, to the standard potential, E degree, and the reaction quotient, Q, by E=E degree -2.303RT/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 72.0 degree C, what is the maximum value of the reaction quotient, Q, needed to produce a non-negative E value for the reaction In other words, what is Q when E = 0 at this temperature? so42-(aq)+ 4h+(aq) +2Br-(aq) Br2(aq) + so2(g) + 2H2o(1) Express your answer numerically to two significant figures.

Explanation / Answer

SO4^2-(aq)+4H^+(aq)+2Br^-(aq) -> Br_2(aq)+SO_2(g)+2H_2O(l)

so,

PSO2=3*10^-5

PV=nRT

or P=CRT

or 3*10^-5=C*(298/12)

or C=1.21*10^-6

so [SO2]=1.21*10^-6

Q=[Br2][SO2]/([SO42-][H+]^4[Br-]^2)

OR 3.8*10^-26=(2.5*10^-4*1.21*10^-6)/(8.3*x^4*12.7^2)

or x=1561.58

so pH=-3.19

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