The process is exothermic.
Heat flows from the system to the surroundings.
The system does work on the surroundings. The system gained energy from the surroundings. The reaction is endothermic. The enthalpy change for the reaction done with twice the stoichiometric molar ratios would be -685 kJ. The enthalpy change would be different if gaseous water were produced. Part II - Problems and Short Answer Questions 7.