For the hypothetical reaction: 2B(g) → B 2 (g); ΔC P [J K -1 ] = 2.0 × 10 -2 T [/K] and ΔH 300 = -40.0 kJ/mol. Estimate the absolute temperature at which ΔH = 0 for this reaction.

Question

TestHub · Accepted Answer

Kirchhoff's equation for enthalpy change is given by:

Δ H_T = Δ H₃₀₀ + ∫₃₀₀^T Δ C_P , dT

Given the values, we have:

Δ H_T = -40000 + 2.0 × 10^-2 ( (T²- 300²)/2 t) J

To find the temperature T where Δ H_T = 0, we set the equation to zero:

0 = -40000 + 2.0 × 10^-2 ( (T²- 300²)/2 t)

0 = -40000 + 0.01 (T² - 90000)

40000 = 0.01 (T² - 90000)

4000000 = T² - 90000

T² = 4000000 + 90000

T² = 4090000

T ≈ √(4090000) ≈ 2022 K

The answer is 2022.

Chemistry - Thermochemistry Question with Solution | TestHub

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