Meals-ready-to-eat (MREs) are military meals that can be heated on a flameless heater. The heat is produced

Question:

Meals-ready-to-eat (MREs) are military meals that can be heated on a flameless heater. The heat is produced by the following reaction: Mg(s) 2H2O(I) → Mg(OH)2(s) + H2(g).
(a) Calculate the standard enthalpy change for this reaction.
(b) Calculate the number of grams of Mg needed for this reaction to release enough energy to increase the temperature of 75 mL of water from 21 °C to 79 °C.