What is the experimental phenomenon of thermite reaction

Initiating a thermite reaction is operated as:

Experimental Operation: 1Take a round piece of filter paper, pour in iron oxide powder, and then pour in aluminum powder.

2.Mix the two well. Use two round pieces of filter paper, fold each into a funnel shape, take out one of them, cut a hole at the bottom, moisten it with water, and then put it together with the other funnel so that there are four layers on all sides.

3.Put it on the iron ring, place the evaporation dish containing sand below, put the evenly mixed iron oxide powder and aluminum powder in the paper funnel, add a small amount of potassium chlorate on top, and insert a magnesium strip in the middle of the mixture, ignite the magnesium strip, and observe the phenomenon.

4.It can be seen that the magnesium strip burns violently, releasing a certain amount of heat, so that the ferric oxide powder and aluminum powder react violently at a higher temperature, releasing a large amount of heat, and at the same time the paper funnel is burned through, and the molten matter falls into the sand, after the molten melt cools, remove the outer layer of dissolved slag, and observe carefully, you can see that it is the iron beads that fall, and this reaction is called thermite reaction. The reaction produces iron and alumina.

Taking advantage of the strong reducing properties of aluminum and the ability of aluminum to release a large amount of heat when converted into alumina, aluminum powder is commonly used in industry to reduce some oxides, and this kind of reaction is called thermite reaction. If iron oxide is replaced with magnesium oxide, the reason why the reaction can occur.

Can ignite this reaction with magnesium strips, of course you can.

When using magnesium bars, please note that the magnesium bars must be polished and shiny, and about 10 cm, too short and not enough heat, too long to burn too long, and cause waste. It is recommended not to add water to the receiving container, otherwise the hydrogen decomposed by water at high temperature is prone to chemical fire. Do not put combustibles, flammables or explosive materials such as glass near the reactants.

When potassium chlorate is used as an oxidant, the dose must not be increased, otherwise it will cause physical fire and chemical fire, before igniting the reactants, evacuate the surrounding personnel and keep a distance. When lighting the magnesium band, a high-temperature lighter, a flamethrower or an alcohol lamp can be used. When you notice that the magnesium bar is gradually turning black and flashing sparks, it means that the magnesium bar has absorbed enough heat and is about to burn, so you should continue to heat it and prepare to evacuate.

After lighting the magnesium band, the experimenter must wear sunglasses or anti-glare equipment to observe the experimental phenomenon to prevent the eyes from being burned by the strong light of the thermite reaction. It is absolutely not permissible to observe the reaction phenomenon next to the reactants. During the reaction, there will be a high temperature of 900 to 1500 degrees Celsius metal melt sprayed, at this time to isolate the surrounding people, do not approach.

After the reaction, it should not be doused with water, but should be allowed to cool naturally. It is recommended not to use a camera to shoot metal oxides such as manganese dioxide, which are prone to violent reactions, and to use a lens that is resistant to strong light or to attach black film to the lens for analysis. After cooling, the reduced metal can be seen, which can be stored or reused.

Experimental Reaction Chemical Equations:

Iron oxide: 2al+fe o 2fe+alo ferric oxide: 8al+3fe o 9fe+4alo manganese dioxide:

4Al+3MNO 3MN+2AL O Vanadium pentoxide: 10AL+3V O 6V+5AL O Chromium oxide: 2AL+CR O 2Cr+AL The principle of thermite reaction is a redox reaction carried out by aluminum elements under high temperature conditions, which reflects the strong reducing property of aluminum.

Due to the extremely low enthalpy of formation of alumina, the reaction will release a huge amount of heat from the sensitive hole, and even the resulting metal will appear in a molten state.

On the other hand, the reaction is carried out in the liquid phase to make the reaction rate extremely fast, and a very large amount of heat is released in a short time. The intensity of the thermite reaction is determined by the oxidation of metal ions. It is estimated that 500 grams of thermite (composed of iron oxide and aluminum) will burn out in 30 seconds.

The thermite reaction uses the reaction of aluminum powder and metal oxides to obtain metal elements, and the reaction is violently exothermic. When the temperature exceeds 1250, the aluminum powder is violently oxidized and emits a lot of heat when burned. The temperature of this exothermic reaction can reach more than 3000 °C.

Thermite reacts very quickly and has a short duration of action.

When ferrosilicon powder is added to the thermite reaction, the effect can be eased and the time of action can be prolonged. For the pouring temperature of about 1000 1100 copper alloy castings, a small amount of strong oxidant can be added, such as sodium nitrate, potassium nitrate, etc.; Magnesium can also be added as an ignition agent to make it chemically react at a lower temperature.

The thermite reaction is extremely dangerous, because the enthalpy of alumina formation is low, it will inevitably cause a large number of high-temperature melt splashes, resulting in serious consequences such as burns. And because of the splash, there is a possibility that other people will be injured. In particular, copper oxide should not be used to configure thermite, as the temperature at which copper oxide reacts with aluminum powder can turn copper into a gaseous state, which is extremely dangerous.

If iron oxide is used in thermite, ferric oxide is recommended instead of iron oxide. Iron oxide decomposes into ferric tetroxide and oxygen at high temperatures. Free oxygen is also very dangerous, and due to the above dangers, it is recommended that the general public do not do this experiment.

1. The conditions for the thermite reaction to occur are at extremely high temperatures. It is a method of using the reducibility of aluminum to obtain high melting point metal element.

2. It can be simply regarded as the reaction between aluminum and some metal oxides (such as Fe2O3, Fe3O4, Cr2O3, V2O5, etc.) under high thermal conditions.

3. Thermite reaction is often used to smelt metals with high melting points, and it is an exothermic reaction, in which magnesium strips are ignition agents and potassium chlorate is combustion supporters. Magnesium strips can be burned in the air, and oxygen is the oxidizing agent. However, when some of the magnesium strips inserted into the mixture are burned, potassium chlorate acts as an oxidizing agent to ensure the continued combustion of the magnesium strips, and at the same time release enough heat to trigger the reaction of iron oxide and aluminum powder.

After the reaction, there is magnesium oxide, potassium chlorate, decomposition products, etc., and alumina forms a mixture, and several of them have darker color strands and do not appear white solids. The alumina is still in the funnel.

The thermite flux in the crucible is ignited and immediately carries out a chemical reaction to generate a certain amount of iron, and the alloying elements are added to adjust the chemical composition to form thermite steel, and at the same time the ALO slag and other components such as MNO and FEO enter the slag, and the reaction is completed in a few seconds.

However, after the reaction is completed, there must be a fixed time of stay (sedation time), that is, the nail can be poured at an appropriate time after the reaction is calmed down, so as to ensure that the reaction is complete and that the thermite steel contains a certain amount of aluminum. The main reaction products of thermite welding are liquid thermite steel and slag.

According to the main chemical reaction formula of thermite welding, the output of pure iron and slag is theoretically calculated, because the reaction cannot be carried out completely, and iron is also mixed in the slag, so in fact, the amount of iron generated is lower than the calculated value The main component of slag is al o.

There are small amounts of iron oxide, manganese oxide and silicic acid. Iron oxide can make the slag black, manganese oxide can make the slag brown, and the slag of normal thermite steel is tan.