Chemical Thermodynamics Problem

JEE Main 2015 Guidance › General Chemistry questions › Chemical Thermodynamics Problem

Determine the enthalpy change for the following reaction at 25Â°C:
C₃H₈(g) + H₂(g) â†’ C₂H₆(g) + CH₄(g)

Using the Standard Heats Of Combustion that are given below....

The Standard heat of formation of C³H₈(g) is -103.8 kJ / mol..

........................Ans: Î”H= -55.7 kJ.

Plz help !

#Chemistry #General Chemistry

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4 Answers

30

Ashish Kothari ·2010-09-20 01:48:35

C₃H₈ â†’ 3C + 4H₂ Î”H_f = 103.8 kJ/mol

3C + 3O₂ â†’ 3CO₂ Î”H_f = 3*(-393.5)=-1180.5kJ/mol

4H₂ + 2O₂ â†’ 4H₂O Î”H_f = 4*(-285.8)=-1143.2kJ/mol

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C₃H₈ + 3C + 4H₂ + 5O₂ â†’ 3C + 4H₂ + 3CO₂ + 4H₂O Î”H = -2219.9 kJ/mol

H₂ + 1/2O₂ â†’ H₂O Î”H= -285.8 kJ/mol

2CO₂ + 3H₂O â†’ 7/2O₂ + C₂H₆ Î”H= 1560 kJ/mol

CO₂ + 2H₂O â†’ 2O₂ + CH₄ Î”H = 890 kJ/mol

------------------------------------------------------------------------------

C3H8(g) + H2(g) â†’ C2H6(g) + CH4(g) Î”H = -55.7 kJ/mol

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Abhisek ·2010-09-20 04:13:49

Thanks a lot for the solution ! :)

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Ashish Kothari ·2010-09-20 04:43:37

Dont say thanks yaar.. You post questions which help us too.. So feel free! :)

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Gurtej Singh ·2010-10-20 00:50:06

Simple HESS LAW.....

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