General Info Chemical Equation: Mg (s) + 2H2O (l) --------> Mg(OH)2 (s) + H2 (g) + 353kJ Solid magnesium and water yields solid magnesium hydroxide, hydrogen gas & 353 kilojoules of heat energy Source- Tocci, Viehland. 1996. Holt Chemistry Visualizing Matter. Austin, Texas: Holt, Rinehart and Winston, Inc. pg. 271, 303

1. What is this chemical reaction used for? An FRH (Flameless Ration Heater) is used to heat the meal. The water reacts with magnesium in a single-displacement reaction. The energy released by this reaction warms the meal (MRE). Source- Tocci, Viehland. 1996. Holt Chemistry Visualizing Matter. Austin, Texas: Holt, Rinehart and Winston, Inc. pg. 271, 303

2. How is the chemical reaction created? The reaction is created by adding water to the Flameless Ration Heater (FRH). The water reacts with Magnesium that is inside the FRH bag and the meal is heated.  Source- Tocci, Viehland. 1996. Holt Chemistry Visualizing Matter. Austin, Texas: Holt, Rinehart and Winston, Inc. pg. 271, 303

3. How is stoichiometry applied to this chemical reaction?

• Stoichiometry is applied to this reaction because we need to figure out how much water and Magnesium will be needed for the meal to be heated. If too much or too little of each is added, then the meal will not be heated properly. 

Source- Tocci, Viehland. 1996. Holt Chemistry Visualizing Matter. Austin, Texas: Holt, Rinehart and Winston, Inc. pg. 271, 303

4. Give a specific stoichiometric problem and solve it for each reactant and product.

• About 353kJ of heat energy is needed to heat the MRE to 60°C

Source- Tocci, Viehland. 1996. Holt Chemistry Visualizing Matter. Austin, Texas: Holt, Rinehart and Winston, Inc. pg. 271

Calculation for the amount of magnesium needed

Calculation for the amount of water needed

Calculation for the amount of magnesium hydroxide Mg(OH)₂ produced

24.0g Mg	1 mol Mg	1 mol Mg(OH)2	58 g Mg(OH)2	=58.0g Mg(OH)2
	24.0g Mg	1 mol Mg	1 mol Mg(OH)2

Calculation for the amount of hydrogen gas H₂ produced

24.0g Mg	1 mol Mg	1 mol H2	2.0 g H2	1000 mL H2	=22254 mL H2
	24.0g Mg	1 mol Mg	1 mol H2	0.08987 g H2

 Source- Stecher, Paul. 1968. The Merck Index- 8th edition. Rahway, NJ: Merck & Co. Inc. pg. 543

5. Are any of your reactants normally the excess or limiting reactant? Explain why. Magnesium is the limiting reactant and is used up completely in the chemical reaction. H2O is obviously the excess reactant. The amount of water that is needed should be specified on the FRH bag because if we were to put more than the correct amount, it would not heat the meal as well as you would like it to do (as stated in #2). Source- Tocci, Viehland. 1996. Holt Chemistry Visualizing Matter. Austin, Texas: Holt, Rinehart and Winston, Inc. pg. 271, 303

6. How much will the main chemical reaction above cost to produce?

Cost for the amount of Magnesium for the above reaction:

Flinn Chemical & Biological Catalog Reference Manual 1999. IL: Flinn, 1999. http://www.flinnsci.com

7. Are their any side reactions or dangers from the original chemical reaction that must be compensated for? If yes, how is it done?

• Hydrogen gas is produced in this reaction. Since it is very flammable, it is recommended that the FRH should be used in a well ventilated area in which there is no risk of fire. Fortunately, Hydrogen is able to quickly escape and no longer be a danger for a long period of time. Another danger is that people can get burned by the reaction of magnesium and water.

• N/A. BlazeTech: Magnesium Fires from Flameless Ration Heaters. <http://www.blazetech.com/magnesium.html>

8. Bibliography

Tocci, Viehland. 1996. Holt Chemistry Visualizing Matter. Austin, Texas: Holt, Rinehart and Winston, Inc. pg. 271, 303 Colburn, Christian. MRE - FRH Offer. 1998. 29 Oct. 1999 <http://www.conquestinc.com/mre_frh.htm> N/A. Flameless Ration Heater. 1996. <http://www.rivard-usa.com/frh.html> N/A. ZestoTherm Flameless Ration Heater FRH. 1998-99. <http://www.quakepro.com/HeaterMeals/zestotherm.htm> N/A. BlazeTech: Magnesium Fires from Flameless Ration Heaters. <http://www.blazetech.com/magnesium.html> N/A. MRE Heaters. 1997. <http://www.c-zone.net/meyerscs/mcs/heaters.html> N/A. Meals Ready to Eat (MRE's) and Food Rations. 1996. <http://www.imsplus.com/ims48.html> *N/A= No Author(s)