Question

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?

Answer 1

Answer:

$\boxed{5.5 \times 10^{-28}}$

Explanation:

We must use the Nernst equation

$E = E^{\circ} - \frac{RT}{zF}\ln Q$

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

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