Answer
25.45 kJ/g
Work Step by Step
The heat capacity of the calorimeter is 7.854 kJ/C and the temperature changes from 23.44C to 30.57C. First we need to find the $\Delta T = 30.57C - 23.44C = 7.13 C$.
Then we find the total amount of energy released by the quinone:
7.854 kJ/C * 7.13C = 55.999 kJ.
Since we dissolved 2.200g of quinone then we have: 55.999kJ/2.2g = 25.45 kJ/g