I had to conduct an experiment to find the enthalpy of reaction for :

4Fe + 3O2 + 6H2O ----> 4Fe(OH)3
In the experiment , I started with an inital temperature of 22.3 C and edned with 36.7 C so the delta T is +14.4C.
Now it's telling me to calcualte the delta Hrxn for the reaction but how can I do that in I don't have mass or specific heat? I tried to use the mass of 4Fe(OH)3 and the specific heat of Iron but I keep getting a positive result and delta H should be negative because this reaction is exothermic. Please Help!