Determine the standard enthalpy of reaction: C₄H₁₀(g) + H₂(g) → 2C₂H₆(g), using the given enthalpies of combustion under standard conditions:
Compound | H₂(g) | C₂H₆(g) | C (graphite)
ΔH° (kJ/mol) | -285.8 | -1560.0 | -393.5
The standard enthalpy of formation of C₄H₁₀(g) is -126.1 kJ/mol

Question

Determine the standard enthalpy of reaction: C₄H₁₀(g) + H₂(g) → 2C₂H₆(g), using the given enthalpies of combustion under standard conditions:

Compound | H₂(g) | C₂H₆(g) | C (graphite)

ΔH° (kJ/mol) | -285.8 | -1560.0 | -393.5

The standard enthalpy of formation of C₄H₁₀(g) is -126.1 kJ/mol

TestHub · Accepted Answer

Δ f H(C 2 H 6 ) = 2(-393.5) + 3(-285.8) - (-1560.0) = -787.0 - 857.4 + 1560.0 = -84.4 kJ. ΔH = 2(-84.4) - [(-126.1) + 0] = -168.8 + 126.1 = -42.7 kJ. This is option (c).

Chemistry - Thermochemistry Question with Solution | TestHub

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