1st year Chemical engineering help!

Hi all, having trouble with this question, any help would be greatly apreciated!

Consider the reaction:

Using the Standard Heat of Reaction at 25oC (-12.9 kJ/mol) and the following thermochemical data, calculate the heat of reaction at 300 oC.

Assume that the molar heat capacities of the various gases depend on temperature according to the following equations:

H2 (g) Cp = 27.14 + 9.27 x 10-3T

I2 (g) Cp = 35.59 + 6.51 x 10-3T

HI (g) Cp = 31.16 -1.43 x 10-2T

Cp is in J/mol K.

All i know is that the answer is to be in kJ/mol and it may involve hess' law, but i am completely stuck! please can anyone help? cheers

Reply 1

michaelyus

snoopjon

Using the Standard Heat of Reaction at 25oC (-12.9 kJ/mol) and the following thermochemical data, calculate the heat of reaction at 300 oC.

Assume that the molar heat capacities of the various gases depend on temperature according to the following equations:

H2 (g) Cp = 27.14 + 9.27 x 10-3T

I2 (g) Cp = 35.59 + 6.51 x 10-3T

HI (g) Cp = 31.16 -1.43 x 10-2T

Cp is in J/mol K.

There is a single differential equation which is applicable in this case. It is derived from the equation for the rate of change of internal energy with respect to temperature dU/dT as a system is heated by δq under constant pressure, which itself can be derived from dU = δq + pdV. Think about what that last term means for a system, and how it is related to enthalpy / heat of reaction.