Find the molar heat of combustion.?

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My answer (3) is incorrect

1 Answer
anor277
Jan 25, 2018

It's option 4.....

Explanation:

By CONVENTION, the enthalpy evolved in an EXOTHERMIC reaction is reported as NEGATIVE....

And so if we made the following measurement for the given reaction...

#C_2H_6(g)+7/2O_2(g) rarr 2CO_2(g) + 3H_2O(l)+Delta#

Enthalpy, i.e. heat, would be EVOLVED, and we would report the associated enthalpy as....#DeltaH_"combustion of ethane"^@=-1422*kJ*mol^-1#.

The given reaction reported the enthalpy AS A PRODUCT; the thermodynamic property is reported as a negative quantity.

As always #DeltaH_"combustion"^@# is the enthalpy associated with the combustion of one mole of substance under standard conditions of temperature and pressure.

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