[jonnyset]

a 2.00 g sample of an organic compound is burned in a colorimeter that has a heat capacity of 10 kJ/degree C. The temperature rises from 23.5 to 25.7 degrees C. Calculate the heat of combustion in kJ/degree C.

The answer is -11.0

Anyone can please explain to me why.

[jacobcolbert]

Well that answer is the heat of combustion for 1 gram.

[Yggdrasil]

For many calculation problems, it helps to chop up the question into smaller calculations.  Here are some questions to guide you to the answer.

1)  How much heat does it take to raise the temperature of the calorimeter from 23.5 to 25.7^oC?
2)  How much heat was released by burining 2g of the compound?
3)  How much heat is released when one gram is burnt?

(note: heat of combusion should be in kJ/g or kJ/mol, not kJ/deg C)