The heat of total cracking of hydrocarbons, ΔH_TC is defined as ΔH at 298.15 K and 101.325 kPa for the process:
C_nH_m + (2n - m/2)H₂(g) → nCH₄(g)
The values of ΔH_TC is -68.0 kJ for C₂H₆ and -95.0 kJ for C₃H₈. Calculate ΔH (in kJ) for
CH₄(g) + C₃H₈(g) → 2C₂H₆(g)

Question

The heat of total cracking of hydrocarbons, ΔH_TC is defined as ΔH at 298.15 K and 101.325 kPa for the process:

C_nH_m + (2n - m/2)H₂(g) → nCH₄(g)

The values of ΔH_TC is -68.0 kJ for C₂H₆ and -95.0 kJ for C₃H₈. Calculate ΔH (in kJ) for

CH₄(g) + C₃H₈(g) → 2C₂H₆(g)

TestHub · Accepted Answer

C 2 H 6 + H 2 → 2CH 4 , ΔH = -68.0 kJ; C 3 H 8 + 2H 2 → 3CH 4 , ΔH = -95.0 kJ. Target = (second) - 2×(first): ΔH = -95.0 - 2(-68.0) = +41 kJ. Answer: 0041.

Chemistry - Thermochemistry Question with Solution | TestHub

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