The junior high school said that FE 0H 3 is a precipitate, but it is a colloid

Fe(OH)3 can be present in colloidal form or in precipitated form, depending on the reaction conditions.

For example, if sodium hydroxide is directly added to ferric chloride, precipitated Fe(OH)3 will be obtained, and if ferric chloride is hydrolyzed, Fe(OH)3 colloids can be formed.

However, relatively speaking, colloids are not in a stable state, for example, under high salt, they will become precipitate.

Colloids are particles with a radius of 1 100 nm

Fe(0H)3 colloid is formed by the aggregation of several Fe(0H)3 particles.

The colloid is charged, and the addition of an oppositely charged solution will convert the colloid into a precipitate.

The metathesis reaction is generally precipitation, and the hydrolysis of iron iron ions produces iron hydroxide colloids.

Colloids are just solids with relatively small particles.

Precipitation can basically be used to make colloids.

Colloidal agglomeration and precipitation are also precipitation.

It should be said that Fe(0H)3 has precipitation and colloid.

When I was in junior high school, I didn't learn what colloids were, so I can only say that it is precipitation. When we learn new knowledge, we will find that many of the original knowledge are problematic or even wrong, and there are many such things.

Fe(OH)3 colloid, you can use a spoon to stir vigorously to become a precipitate, the colloid is stable without external influence, and the precipitate is different.

The colloidal is never precipitated, the colloidal diameter is 1 nm --- 100 nm, and the precipitate diameter is 100 nm

Dilute sulfuric acid is added to the iron hydroxide colloid drop by drop, and a reddish-brown precipitate first appears, and then the precipitate gradually dissolves, and the solution is yellow; Ferric hydroxide colloids are added dropwise to dilute sulfuric acid, and the solution immediately turns yellow; The reaction equation is: Fe(OH)3+3H+=3H2O+Fe3+, The reddish-brown precipitate is produced because iron hydroxide is colloidal, and dilute sulfuric acid is an electrolyte solution, the colloid and the electrolyte solution are polymerized and settled, the precipitation is iron hydroxide, and the neutralization reaction occurs when the dilute sulfuric acid precipitate disappears by continuing to add dropwise dilute sulfuric acid Because the ferric hydroxide colloid is dropped into dilute sulfuric acid, the hydrogen ions are much more than the ferric hydroxide colloid, so the process of iron hydroxide colloidal becoming iron hydroxide precipitation and neutralizing reaction with dilute sulfuric acid is too fast. Therefore, it can only be observed that the solution turns yellow as soon as it is dropped.

The colloids become clear, the color changes to yellow, and there is no Tyndall effect.

1. To be precise, adding a small amount of FeCl3 to generate colloids is this, which is the colloidal test of high three chemicals; More is precipitation.

2 If you look at the cause of colloidal formation, it should be related to the electrical properties of the colloidal belt, and it is a bit forgotten here, 3,1 colloid, this reaction is generated by colloid, unless it is heated.

2 is iron hydroxide. Sulfuric acid is exothermic. Iron hydroxide will be converted into colloids when heated, 2,1, is a precipitation Fe(OH)3 colloids are obtained by the reaction of FeCl3 with boiling water The concentration of OH roots in NaOH is too high, and F3+ ions will precipitate.

2. It should still be iron hydroxide Na2SO4 is added to the iron hydroxide colloid, which will cause polyprecipitation and reddish-brown precipitation. The addition of dilute sulfuric acid will turn into colloids again because the precipitate will gradually dissolve, and the order of magnitude of the molecule will drop from 10 -7 to 10 -9, and the order of magnitude of colloidal molecules is in this range. So it will turn into colloids again, and finally into solutions.

This seems to be the knowledge of analytical chemistry. 1,1.If it is Fe(OH)3 colloidal under boiling water heating conditions, it is precipitated at room temperature.

When added to ferric hydroxide colloid, aggregation and precipitation will occur, resulting in reddish-brown precipitation. The addition of dilute sulfuric acid will turn into colloids again because the precipitate will gradually dissolve, and the order of magnitude of the molecule will drop from 10 -7 to 10 -9, and the order of magnitude of colloidal molecules is in this range. So it will turn into colloids again, and finally into solutions.

0, is the Fe(OH)3 colloid or precipitate formed by the reaction with NaOH and why.

Add to iron hydroxide colloid, produce reddish-brown precipitate, and then add dilute sulfuric acid why does it become colloidal again, is the colloid into iron hydroxide?

Fe(Oh)3 colloidal particles are 1-100 nanometers in size, and there are several or more present in Fe(Oh)3 colloids.

A molecular cluster composed of Fe(OH)3 particles, the diameter of which does not exceed 100 nanometers, is formed at this time.

Fe(OH)3 colloid. When the diameter of this mass exceeds 100 nanometers, a Fe(OH)3 precipitate is formed.

The diameter of the precipitate is larger than that of the colloid.

To prepare Fe(OH)3 colloid, saturated FeCl3 solution should be added drop by drop in boiling water, and continue to boil until the solution is reddish-brown, that is, the heating should be stopped. Note: (1) The experiment process should not be stirred with a glass rod, otherwise the solution will be turbid; (2) When the reaction system is reddish-brown, that is, the iron hydroxide colloid is prepared, the heating should be stopped immediately, otherwise it is easy to appear turbid, resulting in reddish-brown iron hydroxide precipitation.

The equation FeCl3+3H2O===Fe(OH)3+3HCl

If you have any questions, please feel free to ask! (*

The answer you gave upstairs was completely wrong, so don't believe it.

First of all, I will not talk about the phenomenon: at the beginning, there is a reddish-brown precipitate, and with the dropping of dilute H2SO4, the reddish-brown precipitate gradually dissolves, and the solution appears brownish-yellow.

Reason: The first phenomenon: the reddish-brown precipitate at the beginning is due to the strong electrolyte of dilute H2SO4 dropped, which is the change of the electrical properties of the colloidal surface and the precipitation of the colloid.

Therefore, it will produce a brown precipitate of the red chakra.

The second phenomenon: with the dropping of dilute H2SO4, the concentration of dilute H2SO4 increases, so that iron hydroxide.

Dissolves to form iron sulfate.

and water, so the reddish-brown precipitate gradually dissolves, and the solution shows the color of ferric.

Fe(OH)3 colloids are positively charged colloids.

In the question, it is said that H2SO4 is dropped, which means that H2SO4 is a small amount;

At this time, the positively charged Fe(Oh)3 colloidal retaining and negatively charged SO42- occurred as the dominant factors.

If a large amount of H2SO4 is added, then the Fe(OH)3 colloidal will be dissolved in the balance reaction.

Fe(Oh)3 colloidal particles are colloidal particles formed by several Fe(Oh)3 groups together and adsorb ions similar to it. The size of the particles in the same colloid is not the same.

Glue is commonly prepared by FeCl3 hydrolysis method, and the reaction formula is as follows:

fecl3+3h2o== fe(oh)3+3hcl

Part of the solution reacts with Fe(OH)3 and HCl:

fe(oh)3+hcl==feocl+2h2o

Feocl ionization is:

feocl==feo++cl-

FeO+ is an ion similar to Fe(Oh)3, so it is preferentially adsorbed to make Fe(Oh)3 particles positively charged.

What makes the sol stable is the repulsion between the colloidal particles including:

The brown motion of the colloids prevents the sol from settling due to gravity, the so-called dynamic stability. Due to the existence of the electric double-layer structure of the micelles, the colloids all have the same charge and repel each other, so they are not easy to coalesce. This is the most important reason for the stable existence of sols.

The counterions in the electric double layer of the micelle are hydrated, so there is a hydration film on the outside of the particles, which prevents the particles from colliding with each other and making the particles merge and become larger.

The reason for the polymerization and sinking of sols is the attraction between colloidal particles.

If the electrolyte is added to the solution, the electric potential of the colloids is reduced, the thickness of the electric double layer is thinned, and the repulsion effect is greatly weakened.

Fe(OH)3 colloids are positively charged, and after adding H2SO4, they will encounter SO42- and will precipitate, Fe(OH)3 will react with H2SO4 to cause precipitation and dissolution.

2fe(oh)3+3h2so4=fe2(so4)3+3h2o

The colloidal and precipitate of Fe(OH)3 are not two substances, the difference between them is: the size of the dispersed particles of the colloid is 1-100nm, the colloidal Fe(OH)3 colloid is a uniform and stable substance that can penetrate the filter paper, and the precipitate of Fe(OH)3 can be seen by the eye.

Preparation of Fe(OH)3 colloid: 1-2ml of FeCl3 saturated solution is dropped into 20ml of boiling water until the hail balance solution is reddish-brown.

FeCl3 + 3H2O – boiling water) Fe(OH)3 (colloidal) Sun Yanda + 3HCl

One is a complex and the other is a pure matter.