How extreme can highly basic chemicals get

Dispose of chemicals in schools

The disposal instructions for chemicals used and substances received must be checked for all experiments. Small quantities of chemical residues resulting from experiments must be collected in separate containers according to groups. The containers available for this in the laboratory are locked in a cabinet with a permanent exhaust air system in a cool place with a fire-proof environment. They are handed in to a waste disposal company or to a pollutant collection point. Chemical waste is handed in as often as possible.
  • acidn and Bases such as hydrochloric acid and caustic soda can be destroyed by mutual neutralization after dilution with water and poured into the cast. Be careful when diluting sulfuric acid! Acids or bases that are hazardous to the water are also first diluted with water and then carefully neutralized with caustic soda or hydrochloric acid in the fume cupboard. The resulting salt solutions go into container G4.
  • In the container for inorganic Salt solutions with heavy metalsG4 the salts are dissolved in water. The pH value must be kept slightly alkaline (pH = 8), since hydrogen cyanide can form in acidic solutions with nitrogenous salts.
  • Warning: the solid organic waste in the container G3 are flammable.
  • Liquid organic waste in the container G1 are often easily flammable, here particular attention must be paid to good ventilation and fire safety so that no explosive air mixture is created. Halogen-containing organische Waste in the container G2 should only occur in very small amounts in schools.
G1Liquid organic waste without halogens
G2Liquid organic waste containing halogens
G3Solid organic waste
G4Inorganic salt solutions with heavy metals

Special precautions are necessary for many substances and reaction products:
  • Metal scraps and dry metal powder are collected separately in a closed and fire-proof metal container and released as a pollutant as soon as possible. Metal dusts can start to burn especially when they are damp or when they are finely divided and come into contact with the air. You must never put metal powder such as zinc or magnesium powder in a paper basket, especially not in traces on paper! Zinc powder that has not been phlegmatized can self-ignite when exposed to air. Caution: The phlegmatization - the oxide layer created during manufacture - is lost if zinc powder is treated with an acid during an experiment. Only phlegmatized metal powders should be purchased for schools, unsafe old stocks should be given to a disposal company in the original container. Small amounts of moist metal powder residues that react with water, such as moist magnesium or zinc powder, are carefully converted into a soluble salt with dilute hydrochloric acid (caution: strong hydrogen formation and heating, only carry out during the fume cupboard!), The acid is then neutralized with caustic soda, which Saline solutions are disposed of in container G4. Sodium and other alkali metals require special treatment.
  • Inorganic F.efabrics (without metals and without soluble salts) are collected in a fireproof container with a lid and a sand insert. Small amounts of flammable substances such as sulfur or flammable liquids can be carefully burned while the fume cupboard is running. Special measures are necessary for red phosphorus.
  • For example, there are residues that are pyrophoric or that are still one hidden embers or where a post-reaction is possible, measures must be taken to prevent the waste container from starting to burn (measures differ depending on the reaction product: for example, completely burn out, soak, react with hydrochloric acid, use fire-proof containers with sand and a lid ).
  • Become Chemical bottles completely sorted out, the substances should be left in the original bottle and given for disposal.
  • For Glass waste a separate metal rubbish bin with a lid is used so that no glass remains are hidden between rubbish, there is a risk of injury to the cleaning service!
  • Waste bins for paper Chemical waste bins should generally be kept separate from chemistry classrooms. Metal containers with a tight metal lid are also recommended for paper garbage cans, as there are always people who - despite the prohibition - throw away a cigarette or chemical residue. The responsible teacher may then be accused of negligent behavior if a fire breaks out.
  • Small amounts of waste chemicals from test tube experiments that are water-soluble can be diluted with plenty of water and disposed of in the drain; Substances that are hazardous to the aquatic environment, substances with skulls or CMR substances may not be disposed of in this way in the drain.
  • Substances with other waste dangerous reactions must be given separately to the waste disposal service with the contents labeled.

The school and chemistry class are role models for the responsible behavior of students and the proper disposal of hazardous substances. Tips on disposing of chemicals in the household can be found under “Chemicals in the household”, for example. Before the start of each experiment, those involved must clarify which waste and residues arise and how they can be safely disposed of. Information can also be found in the supplier's safety data sheet. The following list provides advice on the disposal of special substances, some of which are no longer allowed to be used in schools.
Ammonium dichromate (explosive with less than 15% water content, carcinogenic)
Moisten with water and hand in the original container to a waste disposal company. No storage in schools!
Asbestos and platinum asbestos (carcinogenic)
Hand it in to a waste disposal company with the note "contains asbestos". Old containers must not be opened or refilled under any circumstances. A platinum-palladium catalyst on pumice stone is suitable as a substitute. No storage at schools, be sure to dispose of it!
Batteries with mercury or batteries with cadmium
Wrap batteries in foil and hand them in to a waste disposal company. Batteries or accumulators of this type are no longer permitted today - apart from a few special applications.
bromine (forms toxic fumes)
Dilute with water and reduce to bromide with sodium thiosulfate. Storage in general education schools is not recommended.
Calcium carbide (forms extremely flammable ethyne with water)
Carefully add water to the residues in the fume cupboard and continuously burn off the resulting ethine with the burner. Neutralize the resulting milk of lime with dilute sulfuric acid, filter the resulting gypsum. The filtrate can be disposed of in the waste water, the residue in the household waste. In schools, dry calcium carbide can be stored in a separate chemical cabinet.

Chromium (VI) oxide (carcinogenic substance)
Hand in the original container to a waste disposal company. Do not open the container, do not moisten the fabric! He can react dangerously with water! Storage in schools is extremely problematic and disposal is recommended.

Cobalt (II) chloride and other cobalt salts (carcinogenic when touched and when the dust is inhaled)
Moisten with water and hand in the original container to a waste disposal company. Student exercises with cobalt salts are not allowed. Storage in schools is problematic.
Diiodopentaoxide (releases iodine when heated and has an oxidizing effect)
Small residues are carefully converted into iodine and oxygen by heating with the burner in a test tube in the fume cupboard. The iodine can be dissolved in ethanol. The ethanolic iodine solution is added to the liquid, organic waste with halogens.

oil or petroleum mixture
Natural petroleum contains many toxic components. This crude oil must not be stored in schools because it also contains benzene, among other things. An "artificial crude oil" is available in the chemical trade for schools, which was produced by the mineral oil industry especially for the distillation experiment.

Acetic anhydride (can react violently with water and especially with acids and alkalis)
Small amounts are diluted in the fume cupboard with plenty of cold water and neutralized with sodium hydrogen carbonate. Then you put the liquid in the container for heavy metal salt solutions or dispose of it in the drain. Larger quantities must be collected separately.

Hydrofluoric acid (strong caustic effect, danger to life if touched and if inhaled)
Hydrofluoric acid is by no means part of general education schools. When handling hydrofluoric acid (and hydrogen fluoride), it is essential to wear full protective clothing: full face protection, laboratory coat, rubber jacket, intact fluoroplastic gloves. Hydrofluoric acid could be destroyed according to the following rule: it is diluted with water, then sodium hydrogen carbonate is added for neutralization and then calcium hydroxide is used to precipitate it to form calcium fluoride. The product can be disposed of in receptacle 4. However, it is advisable to leave the destruction of hydrofluoric acid to an expert. If the skin is splashed, there is a risk to life, even if no symptoms appear for the time being after washing off quickly.
Gases in general (Risk of explosion, toxic effect)
Flammable gases such as methane, ethane, propane, butane, ethylene, carbon monoxide can be burned off or sucked off in the explosion-proof fume cupboard, provided that the gases are continuously generated in an apparatus in small quantities. If an explosive mixture has formed in the vessel, fume cupboard or in a room, an ignition source must never be switched on. Smaller quantities of non-flammable gases can be disposed of in the fume cupboard by suction. Toxic gases must not be stored in pressurized gas cylinders in schools.

Iodic acid and periodic acid (oxidative solids)
Moisten it and dispose of it as hazardous waste in a closed container labeled "Oxidizing liquid".

Potassium chlorate (old potassium chlorate is often contaminated and therefore explosive)
Remnants are dissolved in water, then acidified with dilute hydrochloric acid and reduced to potassium chloride with iron or zinc powder. After reaction with sodium hydroxide solution, the solution in vessel 4 is disposed of. In schools, fresh and clean potassium chlorate should only be kept in small quantities in a separate chemical cabinet.

Potassium perchlorate(strong oxidizing agent)
It is recommended to collect the material separately in a container and give it to a waste disposal company as soon as possible. Long-term storage of leftovers is not recommended. In schools, fresh and clean potassium perchlorate should only be kept in small quantities in a separate chemical cabinet.

Potassium dichromate and Potassium chromate (carcinogenic substances)
Moisten with water and hand in the original container to a waste disposal company. Chromates could also be converted into the less dangerous chromium (III) salts with sodium hydrogen sulfite solution (at pH = 2) (wait 2 hours). Storage in schools is prohibited.
Potassium cyanide (highly toxic, risk of release of highly toxic cyanide vapors)
Solutions of the cyanides must on no account come into contact with acids. The solution is adjusted to pH = 11 and copper sulfate is added as a catalyst. Then 30% hydrogen peroxide solution is added dropwise in the fume cupboard and the solution is left for at least two hours. Then it is disposed of in container 4. This is how you could destroy the cyanide, but it is best to leave the disposal to an expert. In case of skin contact there is an acute danger to life! Keeping cyanide in schools is not recommended.
Potassium permanganate(hazardous to the aquatic environment, oxidizing)
Moisten and store tightly in closed container. Dispose of with the special waste marked “Oxidizing solid”. Potassium permanganate can be stored in small quantities in schools.

Sodium azide
Azides decompose with iodine and sodium thiosulfate in aqueous solution to form nitrogen. The same decomposition takes place in an acidified nitrite solution. Small residues can be dissolved in water in a collecting container. The pH value must be adjusted to be pH neutral. Solutions containing azides or original containers are given for chemical disposal with the correct label. Storage in schools is not recommended.

Sodium fluoride and Potassium fluoride
These fluorides can form dangerous hydrogen fluoride with acids. Small amounts of the solutions in water can be destroyed like this: The solution is strongly diluted and neutralized with sodium hydrogen carbonate, then calcium hydroxide is added. The precipitated calcium fluoride goes into the container for heavy metal salts, the fluoride-free filtrate can be put into the wastewater. It is recommended that soluble fluorides not be kept in schools.

Sodium sulfide
React with sodium hypochlorite solution in a fume cupboard. Warning, violent reaction! Let stand for several days with the fume cupboard running, then destroy the remaining oxidizing agent with sodium thiosulphate. Pour reaction product into the container for heavy metal salts. Storage in schools is not recommended.

Old one sodiumand potassium (Formation of explosive gas mixtures on contact with water)
Add small amounts to larger portions of denatured alcohol, use tertiary butanol for potassium, leave to stand for 3 days, due to the evolution of hydrogen only in the fume cupboard, after complete reaction dilute with water and neutralize with dilute sulfuric acid, then it is best to take it to a waste disposal company. Sodium splinters from experiments can be destroyed with water if the safety regulations are observed. Storing potassium in schools is not recommended. Sodium must be stored fresh and oxide-free in paraffin oil. The sodium stocks (in small quantities) are to be checked every six months and renewed if necessary.

Nickel sulfateand other soluble nickel salts (carcinogenic)
Hand in the original container to a waste disposal company. No storage in schools! This substance can be found in old chemistry kits or in crystal growing kits.

Nitrates like Potassium nitrate or sodium nitrate (oxidising, acidic solutions can, when mixed with other substances in container G4, promote the formation of hydrogen cyanide)
It is recommended to collect nitrates separately and dispose of them. Aqueous solutions must be kept alkaline. Small residues from test tube experiments can be disposed of in the drain if the substance is not hazardous to the aquatic environment. Nitrates can be used and stored in schools. Ammonium nitrate may only be used in absolutely pure and dry form; it must be stored in a separate chemical cabinet.

Perchloric acid (can explode in the pure state when heated)
Moisten it and dispose of it as hazardous waste in a closed container labeled "Oxidizing liquid". Storage in schools is not recommended.

Phosgene in gas bottles (highly toxic, danger to life!)
Phosgene and other particularly dangerous contaminated sites - for example gases with fluorine components, ethylene oxide or hydrogen cyanide - may not be disposed of by teachers; they are prohibited in general schools. A specialized waste disposal company must be called in for this.
Whiter phosphorus (toxic, self-igniting in air)
Hand in the shut-off water and a glass container with a tight seal to a disposal company. Warning, the shut-off water is also highly toxic! Smallest amounts can be burned together with ethanol in the fume cupboard. Devices that have come into contact with white phosphorus are burned out and carefully burned, glass devices are rinsed with potassium permanganate. Storage in schools is strongly discouraged.

Red phosphorus (forms corrosive phosphorus pentoxide when burned, forms explosive mixtures with other substances, can convert to yellow phosphorus)
Smallest amounts of phosphorus are burned in a porcelain bowl to which a little alcohol has been added, in a running (and suitable) hood or in the open air. The resulting white phosphorus pentoxide smoke is extremely corrosive. Put on fire-proof protective gloves and protective goggles! It must be checked whether the trigger is suitable for this. When burning in a combustion spoon, make sure that the combustion spoon is absolutely clean and that it has never contained sulfur or other substances. These could react explosively with the phosphorus. All devices that have come into contact with phosphorus must be thoroughly annealed. Then they are rinsed with a 5% sodium hypochlorite solution in the running fume cupboard. Red, contaminated phosphorus must not be kept as disposal residue, as it can gradually turn into yellow phosphorus.

Phosphorus pentoxide (reacts very violently with water)
Small amounts are carefully converted into phosphoric acid with water in the fume cupboard in tiny portions in a container made of Duran glass. Caution, very violent reaction with spray effect possible! Then the treatment is carried out as with an acid.

Picric acid (explosive with less than 23% water content)
Storage in schools is prohibited. If there are still residues, the bottle is left where it is and has a specialist company dispose of it. Screwing on a bottle with dried up residue can be dangerous.

mercury (toxic, especially the fumes)
Carefully collect spilled mercury (only with the mercury absorbent available in the laboratory), this also applies to broken mercury thermometers; Mercury may only be used over a bowl or a tight tray; Residues of mercury or its salts must never be thrown into the garbage or down the drain, this also applies to batteries; they must be collected separately and given to a waste disposal company. Mercury can only be stored in compliance with the regulations: The container with mercury is surrounded by a second plastic container that is secured against breakage, and it stands on a mercury tray in a cupboard with a ventilation system so that it cannot tip over. The set with the absorbent for disposing of mercury in the event of an accident must always be right next to it. Keeping mercury and mercury salts in general education schools is not recommended. The less toxic mercury sulfide is an exception.

Mercury salts like Mercury (II) chloride or Mercury oxide (toxic)
Leave the salts in the original container and, in the case of old bottles, surround them with an additional plastic bottle. Always collect residues separately in double containers - inside glass, outside plastic - with the label and name of the substance, indicate the correct GHS labeling and then hand it over to a waste disposal company. An absorbent for mercury must be available as soon as contaminated sites are found or when mercury salts are available. This is also suitable for mercury salts (observe manufacturer's instructions!).

Carbon disulfide and Ether (very volatile, form explosive mixtures with air)
The smallest residues are carefully burned off in the running fume cupboard or outdoors. The fume cupboard must be suitable for working with the two substances. It should be experimented in such a way that there are as few residues as possible. Leftovers are collected in a bottle with a Teflon cap, labeled and given to a waste disposal company. Only diethyl ether free from peroxides may be stored in a fire-safe safety cabinet under protection from light. Carbon disulfide may only be stored separately in small quantities in a separate safety cabinet.
Silver salts like Silver (I) nitrate or Silver (I) oxide and their solutions

The silver salts (as solids) can be stored in small quantities under light protection at the schools. Silver (I) oxide can be reduced to silver in small quantities (1 g) by heating. Danger! This reaction can also be violent!
Silver nitrate in aqueous solution is reduced to silver by adding iron filings or by heating with glucose. Then you can dispose of the solution in the drain. In general, it is recommended not to store solutions and always use fresh approaches (use a small PE dropper bottle wrapped in aluminum foil!).
Ammoniacal silver nitrate solutions (Tollens reagent, solutions for mirroring) must not be stored under any circumstances, not even for disposal! You destroy them immediately after the experiment by adding glucose, which reduces the silver salt to elemental silver. After filtering off, the filtrate is poured into the sink. The filter paper must be washed out thoroughly and burned on a tripod in the fume cupboard (attention, explosive reaction possible!), Pure silver residues are disposed of as solids. In general, all objects and the base should be rinsed with plenty of water after each work with silver salts. Due to the complex nature of disposal, it is rather advisable not to work with Tollens reagent in general education schools. For mirroring experiments it is recommended not to use more than 3 ml of solution in small test tubes.
Carbon tetrachloride (toxic and hazardous to the aquatic environment)
Dispose of residues in the "halogenated organic substances" collection container, use a brown or light-tight bottle. The storage and use of carbon tetrachloride in schools is generally prohibited.
Hydrogen peroxide and solutions
Dilute with plenty of water and place in a suitable container labeled "Hydrogen peroxide solution". The container must not be tightly closed. Store in a dark and cool place with an exhaust system and hand it in to a waste disposal company. Unstabilized hydrogen peroxide tends to decompose spontaneously, so only the stabilized solution may be stored. Only concentrations up to a maximum of 30% are suitable in the school laboratory. It is stored in a brown bottle in a refrigerator suitable for the laboratory. For student experiments it is recommended to only use solutions up to a concentration of 10%.