How to tell if an acid reacts with iron to form ferrous iron or iron

There are five ways to determine whether an acid reacts with iron to produce iron or ferrous iron:

1. Observe the color of the solution: the color of the solution is yellow, and the color of the solution is light green.

Add NaOH solution: iron produces reddish-brown precipitates, ferrous iron produces white precipitates and quickly turns gray-green and finally reddish-brown.

Add excess copper: iron is iron that decreases and the solution turns blue, and ferrous iron is non-phenomenal.

Add starch ki solution:

The solution turns blue for iron, and for the non-phenomenal is iron.

Add bromine water: iron is not obvious, and ferrous iron can fade bromine water.

Extended Information: Physicochemical Properties of Iron:

It has good ductility, electrical and thermal conductivity.

It is very ferromagnetic and belongs to magnetic materials.

The specific heat capacity is 460J (kg·).

The propagation rate of sound in iron: 5120m s.

Pure iron is soft, but if it is an alloy of iron with other metals or iron mixed with impurities, the melting point is usually lower and the hardness increases.

Iron is an indispensable metal in the industrial sector. Iron is alloyed with a small amount of carbon - steel, which is not easy to demagnetize after magnetization, and is an excellent hard magnetic material, but also an important industrial material, and is also used as the main raw material for artificial magnetism. Iron has a variety of allotropic forms.

Iron is a relatively reactive metal, ranking ahead of hydrogen in the metal activity order table, and its chemical properties are relatively active, so it is a good reducing agent. Iron does not burn in air, but it can burn violently in oxygen.

2-valent ferrous iron, because hydrochloric acid is not oxidizing, cannot oxidize +2-valent ferrous ions to +3-valent iron ions.

When iron reacts with some strong oxidizing substances such as concentrated sulfuric acid, dilute nitric acid or concentrated nitric acid, these oxidizing substances can directly oxidize +2 valence ferrous ions to +3 valence iron ions.

When the acid is a non-oxidizing acid such as hydrochloric acid and dilute sulfuric acid, it is ferrous ions (2-valent) that are generated;

When the acid is an oxidizing acid such as concentrated sulfuric acid and nitric acid, iron ions (3-valent) are generated.

Summary. Hello, glad for your question. Iron and acetic acid react with ferrous iron because acetic acid is a weak acid that converts the oxide form of iron into ferrous iron, which is a more stable oxide form.

When acetic acid reacts with iron, the hydrogen ions in acetic acid convert the oxide form of iron into ferrous iron, which is a more stable oxide form. The oxide form of ferrous iron is more stable than the oxide form of iron, so it is more prone to reactions.

You've done a great job! Can you elaborate on that?

You're glad you asked. Iron and acetic acid react with ferrous iron because acetic acid is a weak acid that converts the oxide form of iron into ferrous iron, which is a more stable oxide form. When acetic acid reacts with cryptoferric, the hydrogen ions in the acetic acid convert the oxide form of iron to ferrous iron, which is a more stable oxide form.

The oxide form of ferrous sizzone is more stable than the oxide form of iron, so it reacts more easily.

If it is an experiment, you can judge whether trivalent iron or divalent iron can be judged by the yellow or green color of the solution, only oxidizing acid can be directly oxidized to trivalent iron, like dilute hydrochloric acid, dilute sulfuric acid is not oxidizing, so it is divalent iron, oxidizing acid like nitric acid, and concentrated sulfuric acid can be oxidized to trivalent iron.

1. All iron reacts with dilute sulfuric acid to form 2-valent iron.

Iron reacts with concentrated sulfuric acid, because it will be passivated, and it is also difficult to produce 3-valent iron.

You can add a little oxidant to dilute sulfuric acid, such as oxygen, so that 3-valent iron can be formed.

2-valent iron is light green in solution, 3-valent iron is yellow in solution, if the solubility is high, it will turn brown, generally do not need to look at the color judgment, the laboratory identification method is to add KSCN, if there is a blood-red complex to produce 3-valent iron, otherwise it is 2-valent iron.

If you don't learn this, you can add an excess of NaOH, if there is a gray-green precipitate that quickly changes to reddish-brown at the beginning, it means that it is 2-valent iron, and if it directly produces a reddish-brown precipitate, it is 3-valent iron.

2-valent iron is pale yellow or light green, 3-valent iron is brownish-red, or NaOH is added to the pH value greater than 7, which produces a white precipitate that is 2-valent iron, and there is a red precipitate with 3-valent iron.

Concentrated sulfuric acid: 3-valent.

Dilute sulfuric acid: 2-valent.

Excess nitric acid: 3-valent.

Insufficient nitric acid: 2-valent.

Hydrochloric acid: 2-valent.

As long as the amount of acid is sufficient, there will be no iron residue.

For example, in the reaction with hydrochloric acid: Fe + 2HCl = FeCl2 + H2, for every 56 grams of iron, 73 grams of HCl are required to participate in the reaction. (Based on the concentration of concentrated hydrochloric acid, the quality of concentrated hydrochloric acid required is 200g).

Another example is with sulfuric acid: Fe + H2SO4 = FeSO4 + H2, for every 56 grams of iron, 98 grams of H2SO4 are needed to participate in the reaction. (Based on the concentration of 20% dilute sulfuric acid, the mass of the sulfuric acid solution required is 490 grams).

Sulfuric acid here refers to dilute, because dilute sulfuric acid and hydrochloric acid are both non-oxidizing acids, so low-cost salts are generated, and nitric acid is oxidizing regardless of concentration, so ** salts are generated.

Iron and acetic acid do not react.

Why does iron react with acid and react with salt solution to form ferrous salts: concentrated sulfuric acid reacts with iron under heating conditions to form ferric chloride, while concentrated hydrochloric acid reacts with iron to form ferrous chloride, in fact, the difference is that the concentration of concentrated sulfuric acid is more than 90%, and even up to 98 points, and we generally call concentrated hydrochloric acid is only 20%-30%, the concentration is not very large, the oxidation of natural concentrated hydrochloric acid is not as good as the oxidation of concentrated sulfuric acid, so the reaction between concentrated hydrochloric acid and iron produces ferrous chloride instead of ferric chloride.

Equation: Fe + 2HCl = FeCl2 + H2 (gas) Ferrous chloride: ferrous chloride, chemical formula FeCl2.

Green to yellow in color. Soluble in water, ethanol and methanol. There are tetrahydrate FeCl2·4H2O, which is a transparent blue-green monoclinic crystal.

Density gram cm3. Easy to deliquescent. Soluble in water, ethanol, acetic acid, slightly soluble in acetone, insoluble in ether.

In the air, it will be partially oxidized and turn grass green. It is gradually oxidized to ferric chloride in the air. Anhydrous ferrous chloride is a yellow-green hygroscopic crystal that forms a light green solution when dissolved in water.

Salt of four waters. When heated, it becomes salt dihydrate.

Acids are non-strongly oxidizing salts, and the oxidizing properties of salts cannot oxidize iron to trivalent.

Fe reacts with a small amount of dilute Hno3 to obtain the equation of Fe(No3)2 total anti-orange split orange mass as .

3fe+8hno3=＝＝3fe

no3)22no↑

4h2o (heat if necessary).

It can be understood that Fe is oxidized by Hno3 to Fe3+, and the excess Fe reacts with Fe3+ to obtain Fe2+

Fe reacts with dilute Hno3 of slag infiltration and a small amount of skin to ignite the beam judgment, and Fe(No3)23Fe + 8Hno3 3Fe is obtained

no3)22no↑

4H2O can also be replaced with copper nitrate.

cu(no3)2+fe=fe(no3)2+cu