When 1.365 g of anthracene, C14H10, is combusted in a bomb calorimeter that has a water jacket containing 500.0 g of water, the temperature of the water increases by 25.89°C. Assuming that the specific heat of water is 4.18 J/(g ∙°C), and that the heat absorption by the calorimeter is negligible, estimate the enthalpy of combustion per mole of anthracene.

The law of conservation of energy can be applied to heat changes, i.e. the heat received/absorbed is the same as the heat released  

Q in = Q out  

Heat can be calculated using the formula:  

Q = mc∆T  

Heat released by anthracene= Heat absorbed by water

Heat absorbed by water =

mol of  anthracene (MW=178,23 g/mol)

The enthalpy of combustion per mole of anthracene :

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.