A 2.50 g sample of powdered zinc is added to 100.0 ml of a 2.00 M aqueous solution of hydrobromic acid in a calorimeter. The total heat capacity of the calorimeter and solution is 448 J/^ C . The observed increase in temperature is 21.1 degrees * C at a constant pressure of 1 atm. Using these data, calculate the standard enthalpy of reaction.
Zn(s)+2 HBr(aq) = ZnBr 2 (aq)+H 2 (g)
What is delta H rxn in kJ/mol?