Problem: 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) + 2 H2O(l) → Mg(OH)2(s) + H2(g).Calculate the number of grams of Mg needed for this reaction to release enough energy to increase the temperature of 76 mL of water from 26˚C to 76˚C.

FREE Expert Solution

ΔH°rxn=ΔH°f, prod-ΔH°f, react

ΔH°rxn=(1 mol Mg(OH)2)-924.5 kJ1 mol Mg(OH)2+0           -0+(2 mol H2O)-241.8 kJ1 mol H2O

Hrxn=-682.7 kJmol×103 J1 kJ

ΔH˚rxn = –6.827 × 105 J/mol



q=mcTq=mc(Tf-Ti)

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Problem Details

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) + 2 H2O(l) → Mg(OH)2(s) + H2(g).

Calculate the number of grams of Mg needed for this reaction to release enough energy to increase the temperature of 76 mL of water from 26˚C to 76˚C.