home Calculators Is sodium stored under a layer of kerosene? Chemical properties

Is sodium stored under a layer of kerosene? Chemical properties

CLEANING ALKALI METALS FROM OXIDE FILMS

It is recommended to remove oxide films from the surface of pieces of lithium and sodium with a sharp knife under a layer of xylene or mineral oil, previously dried over a sodium wire. The operation is conveniently carried out in a porcelain mortar. The cleaned pieces of metal are transferred with tweezers into a glass or flask with dried xylene. After carefully decanting the xylene, the metal scraps are immediately destroyed.

When purifying potassium, this technique cannot be considered safe, although it is recommended in some manuals. When a fresh potassium surface comes into contact with an oxide film, explosions sometimes occur even under a layer of protective liquid.

Much safer, more economical and easier way purification of potassium, which consists of melting the metal under a layer of dried heptane. Small crude pieces (about 20 g) are melted in a wide-neck Erlenmeyer flask or in a tall glass. After the metal has melted, the heating is stopped and by carefully rotating the flask, ensure that the potassium flows out of the oxide films. If smaller pieces are needed, carefully shake the flask or use a glass rod to break the portion into several globules. Next, the flask is cooled and when the metal hardens, the globules are removed using a sharp iron rod or long tweezers and transferred to a tared bottle with heptane for subsequent weighing. Remaining films must be immediately destroyed.

The described technique is also suitable for sodium purification. In this case, dried xylene is used instead of heptane.

DISPOSAL OF ALKALINE METALS RESIDUE

Lithium waste

Scraps and small (no larger than a pea) pieces of lithium can be destroyed by dissolving them in plenty of cold water in a fume hood.

Due to their high reactivity, lithium dispersions cannot be dissolved in water. The remaining dispersion in the hydrocarbon solvent is destroyed by the gradual addition of ethyl alcohol.

Sodium waste

Trimmings and sodium residues in quantities of no more than 5-10 g are immediately destroyed by pouring small portions of ethyl alcohol into them until completely dissolved. It is allowed to use isopropyl alcohol containing up to 2% water to speed up the reaction.

There is a way to destroy small pieces of sodium in a flask of cold water. A layer of gasoline 3-5 cm thick is poured on top of the water. Pieces of sodium are lowered one by one into the flask. The next piece is added only after the previous one has completely dissolved. Sodium dissolves at the phase boundary, the protective layer of gasoline prevents the ignition of hydrogen. The method is convenient, but from a safety point of view it has no advantages over conventional methods.

It is necessary to monitor the complete dissolution of sodium when treating sludge with ethyl alcohol after reactions. Thus, excess sodium after the Wurtz reaction cannot always be completely destroyed with alcohol, since pieces of sodium are covered with a crust of halides insoluble in alcohol. Subsequent rinsing with water in such cases leads to ignition of the mass.

Sodium dispersions are decomposed by adding anhydrous alcohol drop by drop without access to air.

Potassium waste

This waste is destroyed by filling it with a mixture of equal quantities of petroleum ether and anhydrous isopropyl alcohol.

Even with rubs-butyl alcohol, the reaction may proceed too violently.

Destruction is carried out in a glass under a layer of xylene, adding drops rubs-butyl alcohol. The operation is carried out in a fume hood with the doors closed, with fire extinguishing agents at the ready.

At proper organization work in the laboratory, when the scraps do not accumulate, but are destroyed in a timely manner, there is no need to destroy large quantities of alkali metals.

13. Safety precautions when working with
concentrated acids and alkalis

When working with concentrated acids and alkalis, the following precautions must be observed:

1. Pour the specified liquids only through the funnel into fume hood.

2. When diluted concentrated sulfuric acid pour the acid in portions into the water and stir vigorously;

3. When diluted with water concentrated acid, when preparing a chrome mixture, when mixing concentrated sulfuric and nitric acids, you can only use thin-walled cookware.

4. Dissolve caustic alkalis follows by slowly adding small pieces to the water; Take pieces of alkali with tongs or a spatula.

5. Caustic, aggressive, defiant chemical burns substances, concentrated acids - hydrochloric, nitric, sulfuric, hydrofluoric and chromic anhydride, dry alkalis - sodium and potassium hydroxides and their concentrated solutions, as well as ammonia solutions, when they come into contact with the skin, cause burns. A particular danger lies in the possibility of eye damage. For any work with caustic substances Necessarily apply protective glasses or masks, gloves .

6. Store caustic substances only in thick-walled glass containers with a capacity of no more than 2 liters in a fume hood.

7. Overfill acids only when the draft in the fume hood is on. Cabinet doors should be closed whenever possible. It is recommended to transfer acids using a special siphon.

8. Flasks with concentrated acids, and bromine carry only in a bucket, and when pouring, the bottle should not be held by the neck.

9. When working with smoking nitric acid And oleum, except
glasses, wear long rubber apron.

10. It is prohibited to use sulfuric acid in vacuum desiccators as a water-absorbing agent.

11. Working with hydrofluoric acid requires special care. Necessarily wear rubber gloves, safety glasses and carry out all work only under traction.

12. Spilled acids and alkalis should be immediately neutralize and only after that carry out cleaning.

13. Prohibited draw up solutions of acids and alkalis by sucking them into a pipette with your mouth.

CLEANING ALKALI METALS FROM OXIDE FILMS

A much safer, more economical and simpler method of purifying potassium is to melt the metal under a layer of dried heptane. Small crude pieces (about 20 g) are melted in a wide-neck Erlenmeyer flask or in a tall glass. After the metal has melted, the heating is stopped and by carefully rotating the flask, ensure that the potassium flows out of the oxide films. If smaller pieces are needed, carefully shake the flask or use a glass rod to break the portion into several globules. Next, the flask is cooled and when the metal hardens, the globules are removed using a sharp iron rod or long tweezers and transferred to a tared bottle with heptane for subsequent weighing. Remaining films must be immediately destroyed.

The described technique is also suitable for sodium purification. In this case, dried xylene is used instead of heptane.

DISPOSAL OF ALKALINE METALS RESIDUE

Lithium waste

Scraps and small (no larger than a pea) pieces of lithium can be destroyed by dissolving them in plenty of cold water in a fume hood.

Due to their high reactivity, lithium dispersions cannot be dissolved in water. The remaining dispersion in the hydrocarbon solvent is destroyed by the gradual addition of ethyl alcohol.

Sodium waste

Sodium dispersions are decomposed by adding anhydrous alcohol drop by drop without access to air.

Potassium waste

This waste is destroyed by filling it with a mixture of equal quantities of petroleum ether and anhydrous isopropyl alcohol.

Even with rubs-butyl alcohol, the reaction may proceed too violently.

With proper organization of work in the laboratory, when scraps do not accumulate but are destroyed in a timely manner, there is no need to destroy large quantities of alkali metals.