Why don t you need MnO2 catalysis for thermite reaction experiments with aluminum powder and iron ox

Thermite reaction. It is often used to smelt metals with high melting points, and it is an exothermic reaction, in which magnesium strips are the ignition agent, potassium chlorate.

for accelerants. 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 that the magnesium strips continue to burn, and at the same time release enough heat to trigger the reaction between metal oxides and aluminum powder.

The addition of mnO2 catalyzes the decomposition of potassium chlorate into oxygen to obtain a better oxidation effect, so Mno2 is not needed in the thermite reaction.

Expression: 2yal+3mxoy=high temperature=yalo +3xm(m is a metallic element).

Experimental Reaction Chemical Equations:

Iron oxide. 2Al+Fe2O3==High temperature==2Fe+AlO

Ferric oxide.

8al+3fe3o4==high temperature==9fe+4alO

Manganese dioxide. 4AL+3MNO2==High temperature==3MN+2ALO

Vanadium pentoxide.

10AL+3V2O5==High temperature==6V+5ALO

Chromium oxide: 2Al+Cr2O3==High temperature==2Cr+AlO

Thermite reaction trimming technique: take the least common multiple of oxygen on both sides of the oxide in the reactant and the product.

It can be quickly balanced, such as in the thermite method, the least common multiple of oxygen in Fe O and Al O can be taken 12, then Fe O should be 3 before Al O, Al O should be 4 before, Al can be obtained at the bottom of Al is 8, Fe is 9).

This reaction uses the reducibility of aluminum to obtain a high melting point of metallic iron, which generates a large amount of heat during the reaction, and the reaction speed is very fast, so there is no need for a catalyst. Moreover, manganese dioxide and aluminum will undergo a reduction reaction, let alone catalyze.

Safe and easy-to-use solution:

Guide the fire rope: potassium chloroate: potassium nitrate 1:5 mixed solution soaked in toilet paper, dried and kneaded into strips.

Ignition agent: potassium permanganese + magnesium powder.

Potassium nitrate + magnesium powder.

Potassium chloroate + magnesium powder.

Potassium chloroate + sulfur powder + aluminum powder.

Various thermite components:

Iron oxide + aluminum powder.

Manganese dioxide + aluminum powder.

Copper oxide + aluminum powder (this will fry, but the mushroom cloud is spectacular + the sound effect is right) molybdenum oxide + aluminum powder.

Lead oxide + aluminum powder.

As for the proportion, it is calculated according to the oxygen balance, and it is enough to match it with 0 oxygen balance.

mg and KCIO3Magnesium strips are used as ignition agents and potassium chlorate is used as accelerants.

2al+fe2o3=2fe+al2o3

Iron oxide refers specifically to Fe2O3, and there are three common iron oxides: FeO, Fe2O3, and Fe3O4

The main difference between the three is valency and color.

Feo is black and the valency of iron is +2 valence.

Fe2O3 is reddish-brown and the valency of iron is +3 valence.

Fe3O4 is black, and the valency of iron: +2, +3 valence, is magnetic, also known as magnetic iron oxide.

4Al+2Fe2O3 - 2Fe+2Al2O3 (reaction conditions: high temperature) Iron oxide is a pure substance only Fe2O3

FEO: ferrous oxide black powder.

Fe2O3: ferric oxide, reddish-brown, can be used as a red paint, Fe3O4: ferric oxide, black crystals.

(1) At high temperature, aluminum and iron oxide undergo a displacement reaction and release a large amount of heat at the same time, and the reaction equation is: 2Al+Fe2O3

2Fe + Al2O3, this reaction is also called thermite reaction, so the answer is: 2Al+Fe2O3

2fe+al2o3；

2) Copper and dilute nitric acid react to produce copper nitrate and nitric oxide, no is a colorless gas, no is unstable and easy to be oxidized to form reddish-brown gas nitrogen dioxide, in the reaction, the valency of cu element changes from 0 valence to +2 valence, and the valency of n element changes from +5 valence to +2 valence, so nitric acid is an oxidizing agent and copper is a reducing agent, so the answer is: no; reddish-brown; hno3；cu．

In the first one, AL and XFEO?YFE2O3 powder to obtain FE and Al2O3, and then react with sufficient hydrochloric acid, reaction: Fe + 2HCl = FeCl2 + H2, the second part directly put a sufficient amount of caustic soda solution, the reaction: 2Al + 2NaOH + 2H2O = Naalo2 + 3H2, the mass ratio of the gas generated in the two cases before and after is 5:7, so that the amount of hydrogen substances generated in the first and second parts is 5mol and 7mol respectively, then:

fe+2hcl=fecl2+h2↑

5mol 5mol

2al+2naoh+2h2o=naalo2+3h2↑2 37mol×2

3 7mol

Order xfeo?The average valency of FE elements in YFE2O3 is A, according to Al and XFEO?Conservation of electron transfer in YFE2O3 reaction: 7mol2

3 3=5mol (a-0), the solution is a=, so 2x+2y 3

x+2y

Let the mass of the first part react with hydrochloric acid to produce hydrogen is 5g, and the mass of the second part reacts with hydrochloric acid to produce hydrogen 7g

Let the mass of the iron reduced by the reaction of aluminum powder and iron oxide be A, and the mass of the aluminum powder used is B

fe+2hcl=fecl2+h2↑ 2al+6hcl=2alcl3+3h2↑

a 5g b 7g56a

25g54b＝6

7ga=140g b=63g

Let the mass of aluminum reacted with ferrous oxide be m, and the mass of iron formed is n

2al+3feo high temperaturealo+3fe

m n54m

The mass of aluminum reacted with iron oxide is 63 g-m by nm=9n28, and the mass of iron formed by reaction with iron oxide is 140 g-n

2al+fe

o High temperatureal

o+ 2fe

63g-m 140g-n

5463g?m

140g?n

Substitute m=9n28 into 5463g?m

140g?n

It can be solved n=28g

Then the mass of ferrous oxide = 28g 56

72=36g

The mass of the iron element in iron oxide = 140g-28g = 112g, and the mass of iron oxide = 112g 112

160=160g

The mass ratio of ferrous oxide to iron oxide is 36:160, and the relative molecular mass ratio of ferrous oxide to iron oxide is 72:160

x：y=36

160=1:2, so choose b

Each serving contains 1molal, which can be obtained according to the equation for a complete reaction at high temperature, and then a sufficient amount of dilute sulfuric acid.

2al-3fe-3h2

1mol so a=;

For directly putting a sufficient amount of caustic soda solution, 2al-3h2 can be obtained according to the equation

1mol so b=, under the same conditions, the ratio of volume is equal to the ratio of the amount of matter, so a:b=::1 so choose a

Set each part of aluminum powder and iron oxide, of which 2mol of aluminum and 1mol of iron (according to the chemical reaction equation).

2mol of aluminum powder and 1mol of iron oxide react to form 1mol of alumina and 2mol of iron, 1mol of alumina and dilute sulfuric acid react without hydrogen, and 2mol of iron and dilute sulfuric acid react to form 2mol of hydrogen. The other part is directly added to caustic soda, 1mol of iron oxide and caustic soda react without producing hydrogen, and 2mol of aluminum reacts with caustic soda and water to produce 3mol of hydrogen.

So a:b is 2:3

The above is based on the chemical reaction equation, because it is more difficult to type, so it is explained.

From the complete reaction, n(fe)=n(al).

Whereas, Fe+2H+=H2+Fe2+

2al+2h2o+2oh-=3h2 +alo2-then a b=2 3