At 66.0 ∘c , what is the maximum value of the reaction quotient, q, needed to produce a non-negative e value for the reaction so42−(aq)+4h+(aq)+2br−(aq)⇌br2(aq)+so2(g)+2h2o(l) in other words, what is q when e=0 at this temperature?

Respuesta :

znk

Answer:

[tex]\boxed{5.5 \times 10^{-28}}[/tex]

Explanation:

We must use the Nernst equation

[tex]E = E^{\circ} - \frac{RT}{zF}\ln Q[/tex]

Step 1. Calculate E°

SO₄²⁻(aq) + 4H⁺(aq) + 2e⁻ ⇌ SO₂(g) + 2H₂O(ℓ)

2Br⁻⇌ Br₂(aq) + 2e⁻                                                                

SO₄²⁻(aq) + 4H⁺(aq) + 2Br⁻(aq) ⇌ Br₂(aq) + SO₂(g) + 2H₂O(ℓ)

E° = 0.17 - 1.0873 = -0.92 V

Step 2. Calculate Q

E   =  0      V

E° = -0.92 V

R = 8.314 J·K⁻¹mol⁻¹

T = 66 °C

n = 2

F = 96 485 C/mol

Calculations:  

T = 66.0 + 273.15 = 339.15 K

[tex]0 = -0.92 - \dfrac{8.314 \times 339.15}{2 \times 96 485}\ln Q\\\\0.92 = -0.0146\times \ln Q \\\\\ln Q = -\dfrac{0.92}{0.0146} = -62.8\\\\Q = e^{-62.8} =\boxed{5.5 \times 10^{-28}}\\[/tex]

The value of q when e = 0 at the given temperature in the question is :

Q =  1.3 * 10⁻²⁶

Determine the value of q when e = 0

Given that

E = 0,  ΔG = -nFE,

therefore ΔG = 0

Also

Given that

ΔG = ΔG° + RTIn q

ΔG° = -  RTIn q

Hence ; Q = e^ (nFE°cell / RT) -- ( 1 )

where : n = 2, F = 96500, E°cell = -0.87 volt, R = 8.314, T = 339 k

insert  values into equation ( 1 )

Q =  1.3 * 10⁻²⁶

Note :  E°cell = reduction half reaction + oxidation half reaction

          = 0.20 volt - 1.07 volt  = -0.87 volt.

Hence we can conclude that The value of q when e = 0 at the given temperature in the question is : Q =  1.3 * 10⁻²⁶

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