How to prepare ferrous sulfate ammonia solution, how to prepare ferrous sulfate solution

Place 50 ml of concentrated sulfuric acid.

Add to about 800 ml of distilled water, cool and dissolve in 40 g of ferrous ammonium sulfate [Feso4·( nh4)2so4·6h2o]。 Dilute to 1,000 millimeters in a volumetric flask. This results in a solution of about 6%.

Because the standard titration solution of ammonium ferrous sulfate is very unstable, especially the change of its concentration should be paid attention to when the room temperature is high, so its concentration should be determined by other standard solutions before each use.

Why do you need to add concentrated sulfuric acid when preparing ammonium ferrous sulfate solution? Mainly because of the ammonia ions and ferrous ions in ferrous sulfate.

It is easy to hydrolyze in water, and this hydrolysis changes the composition of the original solution, so that is to say, the original solution deteriorates, and the ammonia ions and ferrous ions in ferrous sulfate ammonia are hydrolyzed in water The essence of hydrolysis is that ammonia ions and hydroxide ions combine to form a small amount of monohydrate and ammonia molecules, and ferrous ions combine with hydroxide ions ionized by water to generate a small amount of ferrous hydroxide.

Precipitation. The concentration of hydrogen ions in the solution is greater than the concentration of hydroxide ions, therefore, the solution shows acidity, and the way to maintain strong acidity is to add an acid solution to it, increase the concentration of hydrogen ions, due to the hydrolytic equilibrium, the concentration of hydrogen ions increases, and inhibits the two cations.

Therefore, the original solution can still maintain its original composition and will not deteriorate, so the ammonium ferrous sulfate solution should maintain strong acidity.

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Ferrous sulfate is easy to be oxidized, while ammonium ferrous sulfate crystals [(NH4)2SO4·FeSO4·6H2O] are more stable, and ferrous sulfate ammonia solution is not easy to be oxidized during crystallization.

<> ferrous sulfate ionized after dissolving in water has strong reducing property and can also undergo hydrolysis reaction to a large extent. The configuration of ferrous sulfate solution can not directly add ferrous sulfate solid to water to dissolve, the correct preparation method is:

1. Add ferrous sulfate solids to dilute sulfuric acid to prevent hydrolysis to form ferrous hydroxide;

2. After dissolving, add a small amount of reduced iron powder to prevent ferrous ions from being oxidized by dissolved oxygen.

Determined by volumeFerrous sulfate, and then weigh the required amount of sulfuric acid and add water to prepare to the required volume.

For example: with 500ml, you need ferrous sulfate: weigh 5 grams of ferrous sulfate to the beaker.

Add a small amount of water to dissolve and transfer to a 500ml volumetric flask.

Wash the beaker with a small amount of water, then move the washing water to the volumetric flask, repeat 3 times, dilute it with water to the scale, and shake well.

Ferrous sulphate is used in different classifications.

1. Pharmaceutical grade ferrous sulfate: as anemia.

The iron and blood supplements mainly include ferrous sulfate oral liquid, ferrous sulfate blood granules and other products, and iron supplementation for pregnant women. as a local astringent. It is used in the production of local astringent injections.

2. Agricultural-grade ferrous sulfate: fertilize the soil to adjust the acidity and alkalinity of the soil and improve the soil. Or as iron fertilizer, apply to soil or potted plants.

as a plant iron supplement. It can also be used as a pesticide and herbicide.

Used for wheat smut, etc.

The above content reference: Encyclopedia - ferrous sulfate.

Preparation method: weigh ammonium ferrous sulfate and dissolve it in an appropriate amount of water, add 100ml of sulfuric acid solution, dilute it with water to 1L, and store the solution in a brown bottle.

Calibration method: Absorb potassium dichromate standard solution into a 500ml Erlenmeyer flask, dilute to about 110ml with water, slowly add 30ml concentrated sulfuric acid, and mix well. After cooling, add 3 drops of ferrous sulfate indicator solution (approximately, titrate with ammonium ferrous sulfate solution, the color of the solution changes from yellow to blue-green and finally to reddish-brown is the end point.

1. Sulfuric acid method:

Dissolve the iron filings in the mixture of dilute sulfuric acid and mother liquor, and control the reaction temperature below 80, otherwise ferrous sulfate monohydrate will be precipitated. The slightly acidic ferrous sulfate solution generated by the reaction is clarified to remove impurities, and then cooled and centrifuged to obtain light green ferrous sulfate.

2. Production of titanium dioxide by-product method:

When ilmenite is decomposed with sulfuric acid to produce titanium dioxide, ferrous sulfate and iron sulfate are generated, and ferric iron is reduced to divalent iron with iron wire. Ferrous sulfate, a by-product, can be obtained by freezing and crystallization.

3. Metallic iron is dissolved in dilute sulfuric acid to make ferrous sulfate.

The iron wire or iron filings are first treated with sodium hydroxide solution to remove the oil stain, washed with water, put into 15% 20% sulfuric acid solution, heated to dissolve it, until the undissolved residue is no longer dissolved.

The solution is filtered out and transferred to a flask, and acidified with sulfuric acid until Congo red is acidic. After cooling, the hydrogen sulfide reaches saturation, the cork is tightened, and it is allowed to stand for 2 to 3 days, and then the flask is heated on a water bath and filtered to remove carbon, carbide and sulfide precipitation.

The filtrate is transferred to a futz distillation flask, where the solution is evaporated and concentrated to half of its original volume with the introduction of oxygen-free CO2. The solution is allowed to stand in CO2 gas overnight, and the crystals of ferrous sulfate can be precipitated.

1. To remove the oil stain on the surface of the iron filings (such as using pure iron powder, this step can be omitted), weigh 2g of iron filings with a platform scale and put them into a 100ml Erlenmeyer flask, add 15ml of 100g·L-1 Na2CO3 solution, heat slowly for about 10 minutes, pour the lye solution with the decanting method, and rinse the iron filings with deionized water.

2. Prepare ferrous sulfate, add 10ml of 3mol·L-1 H2SO4 to an Erlenmeyer flask containing iron filings, and heat it in a water bath in a ventilated place (pay attention to controlling the rate of anti-noise bending to prevent the reaction from being too fast and the reaction solution is sprayed out) until no more bubbles are released. During the reaction, some water should be added appropriately to maintain the original volume. Filter while hot under reduced pressure.

Wash the residue on the Erlenmeyer flask and funnel with a small amount of hot water, and drain and raise the suffocation. Pour the solution into the evaporation dish.