Thermite Reaction Lab Report
Thermite
Background:
Thermite is a powder made from aluminum powder and a metal oxide [usually iron oxide (Fe2O3, known as rust)]. The thermite reaction is a redox reaction, where Aluminum reduces the oxide of another metal. For example, when using iron oxide (as I did) the equation would be Fe2O3(s) + 2 Al(s) -> Al2O3(s) + 2 Fe(l). Black or blue iron oxide (Fe3O4) could also be used. Other examples of possible oxides are manganese thermite (MnO2), Cr2O3, and copper thermite (CuO). Aluminum can also be replaced by any reactive metal. Aluminum, however, is the safest material and the cheapest to use. Thermite, if you look at the equation, supplies it own oxygen, which means that it can burn under water or in oxygen depleted areas. This also means, however, that the thermite reaction cannot be smothered out and cannot be put out by throwing …show more content…
water onto it.
What happens in a thermite reaction:
In my experiment, I used a 1:3 weight ratio of aluminum powder to iron oxide. If we look at the standard enthalpy values for the products and reactants, we find:
Component Hfo (kJ/mol)
Fe2O3(s) -822.2
Al(s) 0
Al2O3(s) -1,669.8
Fe (s) 0
Fe and Al are zero because the Hfo of elements in their standard states are zero. The ∆H for this reaction is the sum of the ∆Hfo's of the products - the sum of the ∆Hfo's of the reactants (multiplying each by their stoichiometric coefficient in the balanced reaction equation), i.e.:
∆Horxn = (1 mol)( HfoAl2O3) + (2 mol)( HfoFe) - (1 mol)( HfoFe2O3) - (2 mol)( HfoAl)
∆Horxn = (1 mol)(-1,669.8 kJ/mol) + (2 mol)(0) - (1 mol)(-822.2 kJ/mol) - (2mol)(0 kJ/mol)
∆Horxn = -847.6 kJ
That energy change is very large (to put into perspective, the combustion of methane gas, the gas used in Bunsen burners, is -818 kJ/mol). The actual reaction for thermite is: Fe2O3(s) + 2 Al(s) -> Al2O3(s) + 2 Fe(l). solid iron oxide powder, mixed with aluminum powder, goes to aluminum oxide (alumina) and liquid iron. If we look at this equation, we can see that the type of reaction is redox. The thermodynamic driving force for this reaction is the high stability (low free energy) of the aluminia (Al2O3). Another factor is how Al3+ has a greater affinity for oxygen than the Fe3+. This property is called oxophilicity (literally, ‘oxygen loving’).
Alternative procedures
For igniting the thermite, I used a strip of magnesium. This is the most practical and cheapest method. This method, however, does have its disadvantages. While it burns without releasing cooling gases, it is hard to ignite, and in windy/wet conditions, it may get extinguished. Another problem is that magnesium is a very good conductor of heat, meaning that heating one side of the ribbon can cause the other end of the ribbon to get hot enough to cause premature ignition. Another potential problem is that magnesium requires an outside source of oxygen to burn.
One way we could have lighted the thermite is with a potassium permanganate (KMnO4) and glycerine or ethylene glycol. This would have created a reaction that would slowly increase the temperature until flames are produced. This method is also unreliable, however, because factors like particle size and ambient temperature comes into play.
Another fun way to ignite thermite is with your everyday sparkler. This can be a dangerous method because the sparkler sends out iron sparks, which are hot enough to prematurely ignite the thermite (even if they don’t come into direct contact). This is especially dangerous with finely ground thermite.
The grade of the thermite plays a role into this reaction. The more finely powdered the thermite is, the faster and easier it is to light. For example, fine powdered thermite can be lighted with regular lighters, kitchen matches, and even flint spark lighters (the burning of rare earth metals like lanthanum and cerium).
Some experiments call for the molten iron to drip into a bucket of water. This however, is VERY dangerous. Mixing water with thermite is also dangerous. When water is added into thermite, a phreatomagmatic explosion may occur, sending hot materials into all directions. A phreatomagmatic explotion is normally the result of interaction between water and magma. The explotion is composed of magmatic gases and steam from a very hot material (normally magma, but in this case, molten iron).
Other forms of ‘thermite’
There exist different forms of ‘thermite’.
One variety is Thermate. Thermate burns faster and hotter. Thermate is created by combining thermite, sulfur, and barium nitrate. The thermate weight ratio is 69% thermite, 29% barium nitrate, 2% sulfur. There are many other variations of thermite, but thermate is the most common alternate form of thermite.
List of different ‘thermites’:
Iron (III) oxide (Red):
Fe2O3(s) + 2Al(s) → Al2O3(s) + 2Fe(l); ΔH = -847.6 kJ/mol
The ratio of Iron (III) oxide to Aluminum powder by mass is about 3:1. This is the reaction I chose to do.
Iron (II, III) oxide (Black):
3Fe3O4(s) + 8Al(s) → 4Al2O3(s) + 9Fe(l); ΔH = -3347.6 kJ/mol
The reaction using Fe3O4 (-3347.6kJ/mol) produces a substantially larger amount of energy than the reaction using Fe2O3 (-847.6kJ/mol). the weight ratio of Iron (II,III) oxide to Aluminum powder is about 3.2:1. I chose not to do this because of obvious reasons: EXTREMELY hot and much more dangerous. On a more scientific note, the Fe3O4 is known as ‘magnetide’. Magnetide is the most magnetic naturally occurring mineral on
Earth.
Copper (II) oxide (Black):
3CuO(s) + 2Al(s) → Al2O3(s) + 3Cu(l); ΔH = -1203.8 kJ/mol
While this thermite mixture does not produce the same amount of energy as some other compositions--like Iron (II,III) oxide, it does have an incredibly fast burn rate. Copper also has a lower melting point, and this mix should be treated with Extreme caution due to the amount of molten copper produced and the mixture’s tendency to explode. This is caused by the high burn rate. This mixture is known for sending out thousands of drops of liquid metal, and it is recommended that you be very careful when attempting to ignite this compound. The weight ratio of Copper (II) Oxide to Aluminum powder by weight is about 4.4:1. I chose not to do this because of its obvious safety flaws. A Shower of molten copper is not exactly a fun day in chemistry.
Copper (I) oxide (Red):
3Cu2O(s) + 2Al(s) → Al2O3(s) + 6Cu(l); ΔH = -1169.8 kJ/mol
Same story as Copper (II) oxide, just with slightly less heat. Same reasons for not choosing this: while I do enjoy fireworks and spewing hot metal flying everywhere in movies and possibly from very far away, I do not enjoy being rained upon by molten copper. I also believe that Mr. Bett would like to keep his job The ratio of Copper (I) oxide to Aluminum powder by weight is about 8:1
Manganese (IV) oxide (Black):
3MnO2(s) + 4Al(s) → 2Al2O3(s) + 3Mn(l); ΔH = -1788.7 kJ/mol
The ratio of Manganese (IV) oxide to Aluminum powder by weight is about 2.5:1. This version of thermite is harder to get a hold of. Plus, it releases twice the heat of normal thermite.
Cobalt (II) oxide (Black):
3CoO(s) + 2Al(s) → Al2O3(s) + 3Co(l); ΔH = -962.0 kJ/mol
The ratio of Colbalt (II) oxide to Aluminum powder by weight is about 4.2:1. While the amount of heat released by this is similar to the other compounds, it is also a bit harder to get a hold of.
I chose to do thermite out of all of these chemicals because I have really only seen normal thermite reactions on video repeated by college professionals. While I have seen these other examples (like cobalt II, Maganese IV, Iron III, and even a Copper I from very far away), these were done by I assume people like 30 year old versions of Seth and me, who just enjoy lighting things on fire. To be honest, I was scared when I read about the descriptions of what happens during the reactions (like the Copper oxides), and even more scared of the ΔH values.
What had led me to choosing thermite as my experiment was actually a video link that a friend send me from youtube; some college kids melting through a car with thermite. I did some preliminary research on it, and found that there were common experiments people do in college classrooms.
I learned a lot from this lab, like: One should not double the reagents just because a college professor used double of the accepted amount., and One should not rely on school computers because they load too slow. I did enjoy the experience of researching thermite because I had constantly heard of it, and seen the mythbusters of it and the Hindenburg, but I had actually not known a lot about it. If I were to do this over again, I would try to be a bit more prepared to go at the very beginning of class. Overall, it was a great experience.
Background:
Thermite is a powder made from aluminum powder and a metal oxide [usually iron oxide (Fe2O3, known as rust)]. The thermite reaction is a redox reaction, where Aluminum reduces the oxide of another metal. For example, when using iron oxide (as I did) the equation would be Fe2O3(s) + 2 Al(s) -> Al2O3(s) + 2 Fe(l). Black or blue iron oxide (Fe3O4) could also be used. Other examples of possible oxides are manganese thermite (MnO2), Cr2O3, and copper thermite (CuO). Aluminum can also be replaced by any reactive metal. Aluminum, however, is the safest material and the cheapest to use. Thermite, if you look at the equation, supplies it own oxygen, which means that it can burn under water or in oxygen depleted areas. This also means, however, that the thermite reaction cannot be smothered out and cannot be put out by throwing …show more content…
water onto it.
What happens in a thermite reaction:
In my experiment, I used a 1:3 weight ratio of aluminum powder to iron oxide. If we look at the standard enthalpy values for the products and reactants, we find:
Component Hfo (kJ/mol)
Fe2O3(s) -822.2
Al(s) 0
Al2O3(s) -1,669.8
Fe (s) 0
Fe and Al are zero because the Hfo of elements in their standard states are zero. The ∆H for this reaction is the sum of the ∆Hfo's of the products - the sum of the ∆Hfo's of the reactants (multiplying each by their stoichiometric coefficient in the balanced reaction equation), i.e.:
∆Horxn = (1 mol)( HfoAl2O3) + (2 mol)( HfoFe) - (1 mol)( HfoFe2O3) - (2 mol)( HfoAl)
∆Horxn = (1 mol)(-1,669.8 kJ/mol) + (2 mol)(0) - (1 mol)(-822.2 kJ/mol) - (2mol)(0 kJ/mol)
∆Horxn = -847.6 kJ
That energy change is very large (to put into perspective, the combustion of methane gas, the gas used in Bunsen burners, is -818 kJ/mol). The actual reaction for thermite is: Fe2O3(s) + 2 Al(s) -> Al2O3(s) + 2 Fe(l). solid iron oxide powder, mixed with aluminum powder, goes to aluminum oxide (alumina) and liquid iron. If we look at this equation, we can see that the type of reaction is redox. The thermodynamic driving force for this reaction is the high stability (low free energy) of the aluminia (Al2O3). Another factor is how Al3+ has a greater affinity for oxygen than the Fe3+. This property is called oxophilicity (literally, ‘oxygen loving’).
Alternative procedures
For igniting the thermite, I used a strip of magnesium. This is the most practical and cheapest method. This method, however, does have its disadvantages. While it burns without releasing cooling gases, it is hard to ignite, and in windy/wet conditions, it may get extinguished. Another problem is that magnesium is a very good conductor of heat, meaning that heating one side of the ribbon can cause the other end of the ribbon to get hot enough to cause premature ignition. Another potential problem is that magnesium requires an outside source of oxygen to burn.
One way we could have lighted the thermite is with a potassium permanganate (KMnO4) and glycerine or ethylene glycol. This would have created a reaction that would slowly increase the temperature until flames are produced. This method is also unreliable, however, because factors like particle size and ambient temperature comes into play.
Another fun way to ignite thermite is with your everyday sparkler. This can be a dangerous method because the sparkler sends out iron sparks, which are hot enough to prematurely ignite the thermite (even if they don’t come into direct contact). This is especially dangerous with finely ground thermite.
The grade of the thermite plays a role into this reaction. The more finely powdered the thermite is, the faster and easier it is to light. For example, fine powdered thermite can be lighted with regular lighters, kitchen matches, and even flint spark lighters (the burning of rare earth metals like lanthanum and cerium).
Some experiments call for the molten iron to drip into a bucket of water. This however, is VERY dangerous. Mixing water with thermite is also dangerous. When water is added into thermite, a phreatomagmatic explosion may occur, sending hot materials into all directions. A phreatomagmatic explotion is normally the result of interaction between water and magma. The explotion is composed of magmatic gases and steam from a very hot material (normally magma, but in this case, molten iron).
Other forms of ‘thermite’
There exist different forms of ‘thermite’.
One variety is Thermate. Thermate burns faster and hotter. Thermate is created by combining thermite, sulfur, and barium nitrate. The thermate weight ratio is 69% thermite, 29% barium nitrate, 2% sulfur. There are many other variations of thermite, but thermate is the most common alternate form of thermite.
List of different ‘thermites’:
Iron (III) oxide (Red):
Fe2O3(s) + 2Al(s) → Al2O3(s) + 2Fe(l); ΔH = -847.6 kJ/mol
The ratio of Iron (III) oxide to Aluminum powder by mass is about 3:1. This is the reaction I chose to do.
Iron (II, III) oxide (Black):
3Fe3O4(s) + 8Al(s) → 4Al2O3(s) + 9Fe(l); ΔH = -3347.6 kJ/mol
The reaction using Fe3O4 (-3347.6kJ/mol) produces a substantially larger amount of energy than the reaction using Fe2O3 (-847.6kJ/mol). the weight ratio of Iron (II,III) oxide to Aluminum powder is about 3.2:1. I chose not to do this because of obvious reasons: EXTREMELY hot and much more dangerous. On a more scientific note, the Fe3O4 is known as ‘magnetide’. Magnetide is the most magnetic naturally occurring mineral on
Earth.
Copper (II) oxide (Black):
3CuO(s) + 2Al(s) → Al2O3(s) + 3Cu(l); ΔH = -1203.8 kJ/mol
While this thermite mixture does not produce the same amount of energy as some other compositions--like Iron (II,III) oxide, it does have an incredibly fast burn rate. Copper also has a lower melting point, and this mix should be treated with Extreme caution due to the amount of molten copper produced and the mixture’s tendency to explode. This is caused by the high burn rate. This mixture is known for sending out thousands of drops of liquid metal, and it is recommended that you be very careful when attempting to ignite this compound. The weight ratio of Copper (II) Oxide to Aluminum powder by weight is about 4.4:1. I chose not to do this because of its obvious safety flaws. A Shower of molten copper is not exactly a fun day in chemistry.
Copper (I) oxide (Red):
3Cu2O(s) + 2Al(s) → Al2O3(s) + 6Cu(l); ΔH = -1169.8 kJ/mol
Same story as Copper (II) oxide, just with slightly less heat. Same reasons for not choosing this: while I do enjoy fireworks and spewing hot metal flying everywhere in movies and possibly from very far away, I do not enjoy being rained upon by molten copper. I also believe that Mr. Bett would like to keep his job The ratio of Copper (I) oxide to Aluminum powder by weight is about 8:1
Manganese (IV) oxide (Black):
3MnO2(s) + 4Al(s) → 2Al2O3(s) + 3Mn(l); ΔH = -1788.7 kJ/mol
The ratio of Manganese (IV) oxide to Aluminum powder by weight is about 2.5:1. This version of thermite is harder to get a hold of. Plus, it releases twice the heat of normal thermite.
Cobalt (II) oxide (Black):
3CoO(s) + 2Al(s) → Al2O3(s) + 3Co(l); ΔH = -962.0 kJ/mol
The ratio of Colbalt (II) oxide to Aluminum powder by weight is about 4.2:1. While the amount of heat released by this is similar to the other compounds, it is also a bit harder to get a hold of.
I chose to do thermite out of all of these chemicals because I have really only seen normal thermite reactions on video repeated by college professionals. While I have seen these other examples (like cobalt II, Maganese IV, Iron III, and even a Copper I from very far away), these were done by I assume people like 30 year old versions of Seth and me, who just enjoy lighting things on fire. To be honest, I was scared when I read about the descriptions of what happens during the reactions (like the Copper oxides), and even more scared of the ΔH values.
What had led me to choosing thermite as my experiment was actually a video link that a friend send me from youtube; some college kids melting through a car with thermite. I did some preliminary research on it, and found that there were common experiments people do in college classrooms.
I learned a lot from this lab, like: One should not double the reagents just because a college professor used double of the accepted amount., and One should not rely on school computers because they load too slow. I did enjoy the experience of researching thermite because I had constantly heard of it, and seen the mythbusters of it and the Hindenburg, but I had actually not known a lot about it. If I were to do this over again, I would try to be a bit more prepared to go at the very beginning of class. Overall, it was a great experience.