Why is iron hydroxide colloids added to boiling water instead of cold water?

In the production of iron hydroxide colloids, the reaction is reversible when it is added to boiling water, and the increase in temperature helps the equilibrium to move in a positive direction. So use hot water. Extremely strong oxidants, such as sodium hypochlorite, can oxidize freshly made iron hydroxide to + oxidation state of sodium ferrite Na2FeO4 in an alkaline medium.

When heated, it gradually decomposes into iron oxide and water. Insoluble in water, ether and ethanol, soluble in acid, solubility in acid with the length of time to make, the new soluble in acid, if placed for a long time, it is difficult to dissolve. Iron hydroxide can be used to make pigments, medicines, water purification, and can also be used as an antidote to arsenic.

Dropwise addition of hydrochloric acid to the ferric hydroxide colloidal can first make the colloidal polysink, and when the solution is continued dropwise, the precipitate gradually disappears.

Equation: FeCl3 + 3H2O = Fe(OH)3 (colloid) + 3HCl

All of the above ignore an important step.

What is ferrosol hydroxide made of?

Generally, ferric chloride is used, and ferric chloride is added to boiling water (it must be distilled water, otherwise the sol may coalesce) The time is not too long, you can see the translucent reddish-brown sol, so adding it to boiling water is to help the hydrolysis of ferric chloride.

This reaction is reversible, and the increase in temperature helps the equilibrium to move in a positive direction. So use hot water.

At high temperatures, iron hydroxide does not exist as a single molecule or atom, but as a clump, and the requirement to form a colloid is that there is a certain diameter requirement, and the atomic cluster at this time is just right.

When the temperature rises, the solubility of the substance also increases, and the iron hydroxide will not precipitate in hot water, but if it is cold water, it will become a precipitate, and it cannot be made into a colloid.

The use of ferric hydroxide colloidal production is the hydrolysis reaction of ferric chloride: FeCl3 + 3H2O = heating = Fe (OH) 3 (colloid) + 3HCl, which is a reversible reaction, the purpose of selecting saturated solution is to increase the concentration of iron ions, which is conducive to the equilibrium to move to the right, which is more conducive to the preparation of iron hydroxide colloid, and can generate more colloids, if the dilute solution is used, it will lead to the formation of very little colloids.

Iron hydroxide colloids use ferric chloride hydrolysis reaction, ferric chloride hydrolysis reaction: FeCl3 3H2O Fe(OH)3 3HCl, which is a reversible reaction, the purpose of selecting saturated solution is to increase the concentration of iron ions, which is conducive to the equilibrium to move to the right. This is more conducive to the preparation of ferric hydroxide colloids.

A chemical substance with amphoteric but its alkalinity is stronger than acidity, the newly made iron hydroxide is soluble in inorganic acids and organic acids, and can be soluble in hot concentrated alkali. Dilute hydrochloric acid is added to iron hydroxide, and the solution turns yellow.

In the preparation of iron hydroxide colloid, 1-2mol of ferric chloride solution is dropped into boiling water to generate iron hydroxide, which requires aggregation into 1-100nm colloids, which are too thin and too small, and difficult to aggregate into colloids.

The use of ferric hydroxide colloids is ferric chloride hydrolysis reaction, ferric chloride hydrolysis reaction: FeCl3 3H2O Fe(OH)3 3HCl, which is a reversible reaction, the purpose of selecting saturated solution is to increase the concentration of iron ions, which is conducive to the equilibrium to move to the right, which is more conducive to the preparation of ferric hydroxide colloids, why must saturated ferric chloride solution be used when producing ferric hydroxide colloids.

Summary. The reaction condition is boiling water heating.

The reaction condition is boiling water heating.

Wait a minute.

Iron ions are hydrolyzed to form iron hydroxide, which is carried out to a very small extent at room temperature. The hydrolysis reaction is endothermic and buried, and heating and boiling can make the hydrolysis reaction go on to a greater extent and generate colloids. But mainly, after the liquid is reddish-brown, stop the Ming Song and increase the heat, and continue to heat the iron hydroxide to precipitate, because heating is a way to make the colloids sink together.

Thank you. You're welcome, and I wish you all the best!

There are 2 reasons for this:

The positive reaction is an endothermic reaction, so the high temperature is easy to make the reaction in the direction of iron hydroxide.

The thermal movement of particulates in boiling water is vigorous, and iron hydroxide tends to exist in colloidal form instead of directly aggregating and precipitating.

When preparing iron hydroxide colloids, it cannot be heated for a long time, because iron hydroxide colloids can only exist stably under certain conditions, and too long heating time or stirring iron hydroxide will cause iron hydroxide colloids to transform into iron hydroxide precipitation (polyprecipitation).

Original text of the People's Education Edition: Colloids are between the two (solution and turbidity), which can exist stably under certain conditions and belong to the metastable system.

Operation: Take a beaker, add 25ml of distilled water, heat the distilled water in the beaker to boiling, and add 5-6 drops of FeCl3 saturated solution to the boiling water drop by drop. Continue to boil until the solution is reddish-brown and stop heating.

Gather and sink. The reason for colloidal stability is that the colloids have some kind of same charge to repel each other, and the irregular Brownian motion between the colloids also makes the colloids stable. Therefore, the principle of making colloids coalesce is to neutralize the charge of the colloids or accelerate the thermal movement of the colloids to increase the chance of binding of the colloids.

Common Method: Speed up the thermal movement of the colloids to increase the chance of binding of the colloids, so that the colloids aggregate and settle down. The main method is to heat the colloid.

Electrolytes are added. The addition of electrolyte to the colloidal increases the concentration of particles in the colloid, which is contrary to the electrical properties of the colloidal particles, and creates favorable conditions for the charged colloidal particles to attract oppositely charged ions, thereby reducing or neutralizing the charge of the original colloidal particles, so that they lose the factor of maintaining stability. At this time, due to the Brownian motion of the particles, when they collide with each other, they can be gathered.

Settle quickly.

The production of iron hydroxide colloids uses the hydrolysis reaction of ferric chloride

FeCl3 3H2O = Heating = Fe(Oh)3(colloidal) 3HCl, which is a reversible reaction.

The purpose of selecting saturated solution is to increase the concentration of iron ions, which is conducive to the equilibrium to move to the right, which is more conducive to the preparation of iron hydroxide colloids, and can generate more colloids, if the dilute solution is used, it will lead to the formation of less colloids.

1.Under the action of electric current, the colloidal particles move directionally. This indicates that the sol particles have an isotropic charge.

2.There are many impurities in tap water, which contains salts, that is, ions.

3.The ions in tap water will neutralize the charge of the sol particles, resulting in the phenomenon of aggregation and precipitation.

4.Poly-sedimentation: After adding a small amount of electrolyte to the colloid, the ions produced by the ionization of the electrolyte neutralize the charge carried by the colloidal particles, so that the colloidal particles accumulate and grow, and the precipitate of larger particles will be precipitated from the dispersant, this process is called poly-sedimentation.

Summary. Decalescence. The formation of iron oxide colloids is an endothermic reaction, that is, iron oxide reacts with water, and the heat generated will be absorbed, so that the water temperature will rise, and iron oxide will be hydrolyzed to form iron oxide colloids.

In the process of iron oxide colloid, iron oxide reacts with water, and the heat generated will be absorbed, so that the water temperature will rise, and iron oxide will be hydrolyzed to form iron oxide colloid. In the process of iron oxide colloid, iron oxide reacts with water, and the heat generated will be absorbed, so that the water temperature will rise, and iron oxide will be hydrolyzed to form iron oxide colloid. In the process of iron oxide colloid, iron oxide reacts with water, and the heat generated will be absorbed, so that the water temperature will rise, and iron oxide will be hydrolyzed to form iron oxide colloid.

In the process of iron oxide colloid, iron oxide reacts with water, and the heat generated will be absorbed, so that the water temperature will rise, and iron oxide will be hydrolyzed to form iron oxide colloid. Therefore, the formation of iron oxide colloids is an endothermic reaction.

The formation of ferric hydroxide colloids is endothermic or exothermic.

Decalescence. The generation of iron oxide colloids is an endothermic reaction, that is, iron oxide reacts with water, and the heat generated will be absorbed, so that the temperature of water mu will increase, and the oxidized iron will be hydrolyzed to form iron oxide colloids. In the process of iron oxide colloid, iron oxide reacts with water, and the heat generated will be absorbed, so that the water temperature will rise, and iron oxide will be hydrolyzed to form iron oxide colloid.

In the process of iron oxide colloid, iron oxide and water are mutually reciprocal, and the heat generated will be absorbed, so that the water temperature will rise, and iron oxide will be hydrolyzed to form iron oxide colloid. In the process of iron oxide colloid, iron oxide reacts with water, and the heat generated will be absorbed, so that the water temperature will rise, and iron oxide will be hydrolyzed to form iron oxide colloid. In the process of iron oxide colloid, iron oxide reacts with water, and the heat generated will be absorbed, so that the water temperature will rise, and iron oxide will be hydrolyzed to form iron oxide colloid.

Therefore, the formation of iron oxide colloids is an endothermic reaction.

Fellow, I really didn't understand, I can be more specific.

Raw or denier iron oxide colloids are an endothermic process. This is because the formation of iron oxide colloids requires the iron oxide powder to react with water, and this reaction generates heat, which increases the temperature of the water. Reason:

The formation of iron oxide colloids is produced by the reaction of iron oxide powder with water, and this reaction generates heat, which increases the temperature of the water. In order to prevent the water temperature from being too high, you can heat the water to a certain temperature before adding iron oxide powder, and then slowly or repeatedly add iron oxide powder to prevent the water temperature from being too high.

Personal tip: When generating iron oxide colloids, it is important to control the water temperature to avoid overheating and affecting the quality of the final product.

Heat the distilled water in the beaker to a boil, add 5 6 drops of saturated ferric chloride drop by drop to the boiling water.

solution, continue to boil until the solution is reddish-brown, stop heating, and obtain iron hydroxide colloid, colloidal has Tyndall effect.

with a beam of visible light.

Irradiation can be observed to produce a bright pathway, and the colloid meets the electrolyte.

When a small amount of sulfuric acid is added, the ionized ions neutralize the charge of the colloidal particles to make it poly-precipitation, and when the sulfuric acid is excessive, the ionized H+ is ionized

with Fe(OH)3

reaction to dissolve it, so the answer is: saturated FeCl3

Solution; Boiling water; Produce a pathway of light; Precipitation is generated first, and then precipitation is dissolved; When a small amount of sulfuric acid is added, the ions trapped by the electroreed neutralize the charge of the colloidal particles and make them sink together, and when the sulfuric acid is excessive, the ionized H+

with Fe(OH)3

reaction to dissolve