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Heat of reaction Question

Hi guys, pretty stuck on this question and was wondering if anyone has any idea what i should do?



Consider the reaction:

H2 + I2 = 2HI

Using the given thermochemical data calculate the standard heat of reaction at 25 oC.

Standard heat of formation of HI (g) at 1 atm and 25 oC = 24.7 kJ/mol.
Latent Heat of Sublimation at 25 oC = 62.3 kJ/mol.


cheers guys!
Reply 1
snoopjon
Hi guys, pretty stuck on this question and was wondering if anyone has any idea what i should do?



Consider the reaction:

H2 + I2 = 2HI

Using the given thermochemical data calculate the standard heat of reaction at 25 oC.

Standard heat of formation of HI (g) at 1 atm and 25 oC = 24.7 kJ/mol.
Latent Heat of Sublimation at 25 oC = 62.3 kJ/mol.


cheers guys!


Draw a hess cycle involving the sublimation of the iodine(which must be presumed as solid initially in that first equation - otherwise the meaning of the hess cycle is none)

so H2(g) + I2(s) ----> 2HI


H2(g) + I2(g)


Well the gap is supposed to represent arrows.

So enthalpy of reaction = 1*enthalpy of sublimation of I2 + 2*enthalpy of formation of HI = 62.3 + 2*(24.7) = +111.7 kJ

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