Topics in Safety, For abbreviations see Introduction · with alcohol, hydrocarbons and...

© ASE 2003 (adapted from Safety in Science Education, 1996 (HMSO) and Topics in Safety, 1988 & 1982 For abbreviations see Introduction

3-Methylbutanol(iso-amyl alcohol)

F-, Xn Y11 N12 S3 (FC) Suitable for use on small scale as solvent.

3-Methylbutyl ethanoate (iso-amyl acetate)

F- Y12 N13 S4 (FC)

N-methylcarbamide(Methylurea)

Xn Y12 N13 S5

Methyl chloride see ChloromethaneMethylchloroform see 1,1,1-trichloroethaneMethyl cyanide see EthanenitrileMethylene blue solid Xn Teacher/Technician solution Y7 N8 S1Methylene dichloride see DichloromethaneMethyl ethanoate (acetate)

F, Xi Y11 N12 S4 (FC)

Methyl formate see Methyl methanoateMethyl ethyl ketone (M.E.K.) see ButanoneMethyl iodide see IodomethaneMethyl methacrylate see Methyl 2-methylpropenoateMethyl methanoate (formate)

F+, Xi Y11 (N13) S4 (FC)

Methyl 2-methylpropenoate(Methyl methacrylate, Perspex monomer)

F, Xi, Sen

1 to 20% Xi, Sen

(Y12) (N13) (S6) (FC) The substance is a known skin sensitiser and may also be a respiratory sensitiser. Because ofthis and the fact that the vapour is lachrymatory, the depolymerisation of perspex is bestcarried out in a fume cupboard as a demonstration.The polmerisation reaction initiated with is very exothermic if more than a very smallquantity of didodecanoyl peroxide catalyst is used. As supplied the material has a stabiliseradded and this needs to be removed by shaking with dilute sodium hydroxide beforepolymerisation is attempted.

Methyl Orange solid T Teacher/Technician Solution prepared by teacher or technician.

solution 0.04% F Y7 N8 S12-Methylpropan-2-ol(tert-butyl alcohol)

F, Xn (Y11) (N12) S5 (FC)

Methylurea see N-methylcarbamideMillon's Reagent T+, C, N NR NR (S6) This material contains toxic materials as well as concentrated acid. Its use is best avoided in

schools as there are less hazardous alternatives such as Albustix, Sakaguchi test or Cole'smodification of Millon's reagent which provide safer alternatives. See HazChemMan CD2(SSERC) or Hazcards (CLEAPSS).


Millon's Reagent,Cole's modification

T+, C, N (Y9) (N10) (S5) Although this material contains toxic material as well as concentrated acid it is safer thantraditional Millon's reagent. See HazChemMan CD2 (SSERC) or Hazcards (CLEAPSS).

Molybdenum, solid Low hazard Y9 N10 S4 Avoid inhaling any dust if a molydenum alloy is machined or sanded.Nansa acid see Dodecylbenzenesulfonic acidNaphtha F, Xn Teacher/Technician FC This material is not the best for storage of alkali metals as naphthas vary in toxicity owing to

a wide range of compounds; some of these will be Category 2 Carcinogens by the inhalationroute. Liquid paraffin is much safer.

Naphthalen-1-amine (1-naphthylamine)

Xn, N Banned Old samples of the 1- isomer are often impure and may contain traces of the 2- isomerwhich is banned. Banned by virtue of possible impurity.

Naphthalen-2-amine (2-naphthylamine)

T, N, Carc 1 Banned Known carcinogen banned by COSHH.

Naphthalene F-, Xn, N Y12 N13 S6 (FC) Naphthalene is readily absorbed by inhalation and via the skin and is a suspect carcinogen;see Topics 12.2.5. For cooling curves safer alternatives include hexadecan-1-ol andoctadecan-1-ol. Smaller quantities of these should be used and the mixture stirred duringcooling. If a cooling curve particularly for naphthalene is required use a loose plug of cottonwool in the mouth of the tube. Naphthalene should not be heated in an open laboratory.Phenyl benzoate provides a suitable alternatives for recrystallisation experiments.The nitration of naphthalene is not a suitable experiment for schools.

Naphthalen-1-ol (α-naphthol)

Xn Y12 N13 S6

Naphthalen-2-ol(β-naphthol)

Xn, N Y12 N13 S6

These materials should not be nitrated. They are safe to use in the preparation of azo dyesbut these must not be isolated as some insoluble azo-dyes have been shown to becarcinogenic. It is better to use sulfonated naphthols as these form water-soluble azo dyes. Old samples of the naphthalen-1-ol may contain 2-naphthylamine the presence of which isvery hazardous and only samples of known purity > 99% can be considered safe to use.

Nessler's Reagent T+, C, N (Y12) (N13) (S5) The mixture contains potassium iodide, mercury iodide and sodium hydroxide.Alternatively use water test strips.

Nickel ammonium sulfate see Ammonium nickel(II) sulfateNickel, dust Xn, Carc 3, Sen (Y12) (N13) (S6) The dust is a carcinogen by inhalation and the metal is also a sensitiser, causing nickel rash.

However nickel sheet and wire are safe to handle and the metal is commonly used forjewellery and coins. Nickel dusts used as hydrogenation catalysts can spontaneously ignite if exposed to air; afterhydrogenating an oil, store in a lump of the solidified fat.

Nickel salts in general They are carcinogenic by inhalation. The dust is a major problem and care needs to be takenas sensitisation to the material may occur both by inhalation and by skin contact. Take carewith reactions which produce an aerosol, eg dissolving the carbonate in dilute acid orelectrolysis.

solid and solutions > 25% Xn, N, Carc 3(inhal), Sen Y12 N13 (S6) solution 10 to 25% N, Carc 3(inhal), Sen Y9 N10 (S2) Solutions do not seem to present the same problems as some solids but may cause allergic

reactions.

solution 1% to 10% N, Sen Y9 N10 S4 (FC) When nickel plating restrict current to 10 mA cm-2 and carry out in a very well ventilatedroom or preferably in a fume cupboard.


Nickel(II) carbonate, solid Xn, Xi, Carc 3(inhal), Sen Y12 N13 (S5) Substance is dusty; dispense carefully and avoid generating aeosols, eg if dissolving in diluteacid, cover loosely with watch glass or carry out in fume cupboard.

Nickel(II) chloride T, Carc 3(inhal), Sen Y12 N13 S6Nickel(II) nitrate O, T, N, Carc 3, Sen (Y9) (N10) (S4) Crystalline and unlikely to be inhaled unless aerosol created by electrolysis or evolution of a

gas from the same solution.Nickel(II) oxide T, Carc 1(inhal), Sen Not generally recommended This material is carcinogenic by inhalation and is often found in use in Art departments. Its

use is not recommended in schools. It could be adventitiously formed by heating carbonates,nitrates or hydroxides.

Nickel(II) sulfate. solid & solutions >10% (> 0.4M) Xn, N, Carc 3(inhal), Sen Y12 N13 S6 solution 10 to 25% N, Carc 3(inhal), Sen Y9 N10 (S2)Ninhydrin solid Xn Teacher/Technician spray (in butan-1-ol) F-, Xn (Y9) (N10) S5 FC

The material is generally supplied as a solution in butan-1-ol and ignition sources must notbe nearby. Set up in the fume cupboard a disposable spray booth made from a smallcardboard box with one side cut away; this prevents the cupboard from being contaminated.Wear gloves.

Nital (cleaning mixture) F (Y12) (N13) (S6) There are many published recipes for this reagent. Do not use more than 2 cm3 of conc.nitric acid for 98 cm3 ethanol. Mixtures containing larger amounts of nitric acid areunstable.

Nitrates(III) (nitrites) solid O, T, N Y12 N13 S5 Ammonium nitrite should not be heated; nitrogen can be prepared by the teacher heating on

a small scale a dilute solution of ammonium chloride and sodium nitrite. Nitrites react withacid to eventually produce toxic nitrogen dioxide. There is potential for the confusion ofnitrites with nitrates: they are best stored separately.

solutions > 5% (approx. 0.6M) T Y9 N10 S5 1% to 5% XnNitrates(V) (nitrates) Y9 N10 S2 For sources of metal ions in solutionO, Xi

may have additionalhazards depending on thecation

Y11 N12 S5 For heating, testing for nitrates (Devardas Alloy and Brown Ring), etc. The action of heatgenerally produces nitrogen dioxide which is toxic. If, in the thermal decomposition of anitrate, oxygen is being tested for care needs to be taken that the splint does not drop into themolten mass.Nitrates should not be mixed with reducing agents and heated.


Nitric acid fuming (100%) O, C Teacher/Technician FC

If nitrogen dioxide is expected in anything other than the very smallest quantities , a fumecupboard should be used. Nitric acid reacts violently with organic substances, ethanoic acid,ethanol, propanone, aluminium, lithium, magnesium and the alkali metals and thiocyanatesand thiosulfates. Nitric acid should not be used to clean crucibles that have been used toheat magnesium. The use of mixtures of the acid and alcohol to clean glassware is not safefor schools use. If 'Aqua Regia' is used to dissolve metal alloys, the mixture must be madeup using fresh cooled acids and not stored. The production of brown colouration in theliquid is a sign that decomposition has started to occur and the mixture should be disposed ofby pouring into very large volumes of water.

concentrated (70%), (16M) O, C Teacher/Technician FC Preparation of acid from nitrate and conc sulfuric acid.Ostwald process - use small scale apparatus; see Ammonia in HazChemMan CD2 (SSERC).Preparation and use of Aqua Regia.

concentrated (70%), (16M) O, C (Y12) (N13) (S5) (FC) Reactions with copper, on small scale. If nitrogen dioxide is expected in more than smallamounts, use a fume cupboard.

concentrated (70%), (16M) O, C (Y12) (N13) (S6) (FC) Oxidation and nitration of organic compounds. (1M) C Y9 N10 S2 (> 0.8M) C

Comparison of dilute acids and preparation of nitrates. Use 0.5M or even 0.1M wherepossible.

Nitric oxide see Nitrogen monoxideNitroanilines see NitrophenylaminesNitrobenzene T, N Y12 N13 S6 (FC) Readily absorbed via skin and by inhalation. Small quantities may be used in a well

ventilated laboratory. There is a danger of cumulative effects if this compound is handledoften. Small quantities used once or twice in advanced courses by senior students should notpresent a danger. Gloves should be worn.

4-nitrobiphenyl T, N, Carc 2 Banned Banned by COSHH.Nitrocellulose E Not generally recommended Not suitable for use in schools.Nitroaniline see NitrophenylamineNitrogen dioxide T+ FC Very toxic by inhalation and severe irritant to respiratory system, eyes and skin. Delayed

symptoms can follow an exposure and if the gas is inhaled it should be treated as a matter forconcern.Hydrogen ignites spontaneously in air if nitrogen dioxide is present. The reactions of the gaswith alcohol, hydrocarbons and halogenoalkanes are vigorous and dangerous. The gas reactswith amines to form carcinogenic N-nitrosamines.

- cylinders Teacher/Technician Not suitable for schools. - prepared as needed T+ Y12 N13 S6 (FC) Small quantities may be prepared in a well ventilated laboratory by younger students under

supervision. Pupils should be taught how to smell gases safely (See Safeguards 4.3) beforeattempting to smell this gas.

- test tube quantities T+ (Y9) (N10) (S4) Small quantities of metal nitrates may be heated.


Nitrogen monoxide (Nitric oxide)

T+ As with nitrogen dioxide it is very toxic by inhalation and severe irritant to respiratorysystem, eyes and skin. Again delayed symptoms can follow an exposure and if the gas isinhaled it should be treated as a matter for concern.

- cylinders T+ Not generally recommended Not recommended for use in schools. - prepared as needed T+ Y12 N13 S6 (FC) Small quantities may be prepared in a well ventilated laboratory. The gas reacts violently

with methanol. The reaction with carbon disulfide is not recommended as explosions haveoccurred.

- test tube quantities T+ (Y9) (N10) S4 (FC)Nitrogen triiodide E Not generally recommended Preparation not recommended in schools.Nitromethylbenzenes(Nitrotoluenes)

T Not generally recommended Not recommended for use in schools.

2-nitronaphthalenes T, N, Carc 2 Banned Known carcinogen. Effectively banned in schools by government education departments(AMs in England and Wales, SEED Circulars in Scotland and DENI Guidance in N.Ireland)

Nitrophenols Xn (Y12) N13 S6 These compounds should not be made on a preparative scale. Nitrophenylamines (Nitroanilines)

T Teacher/Technician These compounds should not be made on a preparative scale.

4[(4-nitrophenyl)azo]benzene-1,3-diol(Magneson I) and 4[(4-nitrophenyl) azo] naphthalen-1-ol(Magneson II) . solids Xi Teacher/Technician solution (0.5 % in 0.25M sodiumhydroxide)

Xi Y9 N10 S2 Some recipes use 1M sodium hydroxide as the solvent. These solutions are corrosive andbest avoided for use by younger students.

Nitrosamines, in general T & many are potentcarcinogens

Banned Known carcinogens. Effectively banned in schools by government education departments(AM70 in England and Wales, SEED Circular 8/95 in Scotland and DENI Guidance inN.Ireland). Avoid having nitrites or nitrogen dioxide in the presence of amines, especiallysecondary amines, as potent carcinogenic N-nitrosamines will form.

Nitrosonaphthalenes T Banned Effectively banned in schools by government education departments (AM70 in England andWales, SEED Circular 8/95 in Scotland and DENI Guidance in N.Ireland.)

Nitrosophenols, 2- and 3- isomers T Banned Known carcinogens. Effectively banned in schools by government education departments(AM70 in England and Wales, SEED Circular 8/95 in Scotland and DENI Guidance inN.Ireland). These could be adventitiously formed during the nitration of phenol. Nitrationshould not be carried out with the usual nitrating mixture but with a solution of sodiumnitrate and sulfuric acid in an ice bath. The products of the reaction should only be handledwith gloves on and the reaction tube wrapped in paper and discarded at the end of theexperiment. Do not attempt to wash out the tubes.

4-nitrosophenol Xn, N (Y12) (N13) (S6) Unlike other nitrosophenols this material is not thought to be carcinogenic.Nitrotoluenes see NitromethylbenzenesNitrous oxide see Dinitrogen oxide


Octane F, Xn, N Y9 N10 S5 (FC)Oct-1-ene F, Xn Y12 N13 S5 (FC)Oleum' C Not generally recommended Not recommended for use in schoolsOrthophosphoric acid see Phosphoric(V) acidOsmic acid T+ NR NR (S6) Only use with strict supervision.Oxalic acid & oxalates see Ethanedioic acid & ethanedioatesOxygen O - cylinder Teacher/Technician See Handbook (CLEAPSS) or HazChemMan CD 2 (SSERC) for advice on handling

cylinders. - prepared as needed large scale Y12 N13 S6 The preparation of oxygen from potassium chlorate(V) should be avoided. The use of

hydrogen peroxide and manganese(IV) oxide is much safer. small scale Y7 N8 S1 Small scale preparation from manganese(IV) oxide and 5 vol hydrogen peroxide and tests on

the gas.'Oxygen mixture' ( Potassium chlorate (V) plusmanganese(IV) oxide)

Not generally recommended Not recommended for use in schools. Oxygen is best prepared by the action ofmanganese(IV) oxide on hydrogen peroxide solution.

'Paraffin' (Kerosene)

F-, Xn (Y9) (N10) S2 This is the 'paraffin that is used as a fuel. Very flammable only as aerosol or if heated.

Paraffin, liquid ("Liquid paraffin")

Low hazard Y9 N10 S3 Used in cracking hydrocarbon experiments.

Paraldehyde see Ethanal TrimerParaquat T+, N Liquid not suitable for use in schools; material supplied for professional agricultural use is

particularly dangerous. ( Some pesticides may still contain paraquat, but in formulationswhich are very dilute with the chemical incorporated into soluble granules rather than asliquid.)

Pentane F+, Xn, N Y8 N9 S5 (FC) Use on very small scale in well ventilated laboratory or in fume cupboard. Ensure absenceof ignition sources.

Pentan-1-ol and pentan-2-ol(Amyl alcohols)

F-, Xn Y11 N12 S5 (FC)

Pentan-2-one(Propyl methyl ketone)

F, Xn Y11 N12 S5 (FC)

Pentan-3-one(Diethyl ketone)

F, Xi Y11 N12 S5 (FC)

Pentyl ethanoate (Amyl acetate)

F- Y9 N10 S5 (FC) Very small quantity may be used by S1.

perchlorates see Chlorates(VII)Perchloric acid see Chloric(VII) acid


Peroxides, inorganic are generally O, C Y12 N13 S5 Fire or explosion hazard if mixed with metals, non-metals, cloth, paper or wood.but barium peroxide O, XnPeroxodisulfates(VI) (persulphates)

O, Xn, Sen (Y12) (N13) S6 Fire or explosion hazard if mixed with metals, non-metals, cloth, paper or wood.Decomposes slowly and pressure may build up in container.

Petroleum spirits(Petroleum ether fractions)

The 60/80oC fraction contains quite an amount of hexane; if using this fraction take extracare to avoid skin contact with liquid or inhalation of vapour.

bp below 30/40oC F+, Xn, N Y12 N13 S6 (FC) Very small quantities may be used in a well ventilated laboratory provided no sources ofignition are present.

bp below 80oC F, Xn, N Y12 N13 S6 (FC) Small quantities may be used in a well ventilated laboratory provided no sources of ignitionare present.

bp above 80oC F, Xn, N Y9 N10 S2 (FC) Small quantities may be used in a well ventilated laboratory provided no sources of ignitionare present.

Phenol solid T (Y12) (N13) (S5) solution > 5% T Y12 (N13) S5

Use sulfuric acid to prepare methanal / phenol polymers. Do not nitrate with a nitrationmixture, use a mixture of sodium nitrate and acid or 4M nitric acid alone. Rubber gloves need to be worn if the solid is used as phenol is rapidly absorbed through theskin and can cause burns if it comes in contact with the skin. Glycerol orpolyethyleneglycol (PEG) rubbed into the affected area can minimise or even preventblistering.

solution 1 to 5% Xn Y12 N13 S5 Very dilute solutions can be handled by younger students.Phenolphthalein solid Xn Teacher/Technician Preparation of solution. solution in ethanol F Y7 N8 S3 The main hazard is the high flammability of the ethanol.Phenylamine (Aniline) liquid & solutions > 1% T, N, Carc 3 (Y12) (N13) (S6) FC solutions 0.2% to 1% Xn Y12 N13 S6

Rapidly absorbed through the skin; wear nitrile gloves. Phenylamine reacts violently withnitric acid and peroxides. See the sections on naphthalene-1- and -2 -ol for notes on thepreparation of azo dyes. When diazonium compounds are prepared it is important to checkthat the reaction is complete by adding extra nitrite solution and testing a sample withacidified KI solution.

Phenylammonium salts(Anilinium salts)

(FC)

solid & solutions > 1% T, N, Carc 3 (Y12) (N13) (S6) solutions 0.2% to 1% Xn Y12 N13 S6

Being ionic solids these are much less volatile and hence easier to handle than liquidphenylamine. Furthermore in many applications of phenylamine the first step is often theconversion to the salt.

Phenyl benzoate see Phenyl benzenecarboxylate Phenyl benzenecarboxylate(Phenyl benzoate)

Xn Y12 N13 S5 This material is an excellent substitute for benzene in nitration reactions.

Phenyl bromide see BromobenzenePhenyl chloride see Chlorobenzenep-phenylene diamine see Benzene-1,4-diamine


Phenylethanone(Acetophenone or methylphenyl ketone)

Xn Y12 N13 S6 (FC)

Phenylethene (Styrene)

F-, Xn Y12 N13 S6 FC The polymerisation should be initiated with di(dodecanoyl) peroxide. The material has astabiliser added to inhibit autopolymerisation. The stabiliser needs to be removed byshaking with dilute sodium hydroxide solution before the polymerisation is attempted. Useall of the treated phenylethen - do not store.

Phenylhydrazine and salts T Y12 N13 S6 Avoid skin contact.

Phenyl 2-hydroxybenzenecarboxylate(Phenyl salicylate) (Salol)

Low hazard Y7 N8 S3

Phenylmethanol(Benzyl alcohol)

Xn Y12 N13 S6 An alkanol of low volatility and flammability.

Phenyl thiocarbamide (PTC), solid(Phenylthiourea) (PTU)

T+ Teacher/Technician Preparation of strips: For testing the ability to taste this substance, use only a paper strip.Each strip should contain no more than 0.1mg. Stock solutions and solid should be lockedaway and never tasted. Prepare strips by dipping in a solution of no more than 0.1g per litre.

- prepared paper strips (Y9) N10 S3 Taste no more than 2 strips.Phoroglucinol see Benzene-1,3,5-triolPhosphides, metal F, T+, N Not generally recommended Not recommended for use in schools.Phosphine T+ Teacher/Technician FC The preparation of the gas must be carried out in a fume cupboard. Impurities in the gas

render it spontaneously flammable in air. The pure gas will only inflame if it is very dry andthe air is cold.

Phosphoric(V) acid . Liquid C Y12 N13 S6 solution > 25% ( >2.8M) C Y9 N10 S5 10 to 25% (1M to 2.5M) Xi Y9 N10 S4Phosphorus (Red) F, N Y12 N13 TT (FC) Small quantities may be used in a well ventilated laboratory. Forms explosive mixtures with

chlorates and metal oxides. All spatulas etc. that have been used to handle red phosphorusneed to be washed with water, the washings filtered and the filter paper burnt in a fumecupboard. Alternatively simply roast the spatula in a fume cupboard.

Phosphorus (White) F, T+ C, N Teacher/Technician FC Liable to ignite spontaneously; always handle with tongs and cut under water in a strongcontainer such as a mortar. For combustion reactions ignite with a hot glass rod. Whitephosphorus ignites on contact with iodine but explodes with liquid bromine.It is recommended that red phosphorus be substituted for very toxic white phosphorus wherepossible. Though slower to ignite the red allotrope is satisfactory for most applications.In the reaction with chlorine no heat is needed and leaving the solid wet allows time for themaniplulation of the apparatus before the phosphorus ignites.

Phosphorus(V) bromide(Phosphorus pentabromide)

C (Y12) (N13) S6 (FC) Vigorous reaction with water.


Phosphorus(V) chloride(Phosphorus pentachloride)

T+ (Y12) (N13) (S5) (FC) Violent reaction with water, sodium and potassium. Add only a very small amount to wateror to an alkanol in a well ventilated laboratory.For the the preparation of acid chlorides always lead any gases produced down into a sinkwith the tap running and distil the mixture from a water bath, not with direct heat.

Phosphorus(V) oxide(Phosphorus pentoxide)

C (Y12) (N13) (S5) If a crust has formed on the solid it should be removed and treated as a solid acid fordisposal (unreacted oxide will be sticking to the solid). The oxide reacts violently withwater and iodides. Sodium and potassium metals ignite on contact with phosphorus(V)oxide. The oxide must not be used for dehydration of methanoic acid as large volumes of carbonmonoxide are produced. Further information is available on alternative drying agents in the Hazardous ChemicalsManual CD2 (SSERC) or the Handbook (CLEAPSS).

Phosphorus oxychloride,(phosphoryl chloride)

see Phosphorus trichloride oxide

Phosphorus(III) bromide(Phosphorus tribromide)

C (Y12) (N13) (S6) FC Vigorous reaction with water.

Phosphorus(III) chloride(Phosphorus trichloride)

T+, C (Y12) (N13) (S6) FC Violent reaction with water, sodium and potassium. Add only a very small amount to wateror to an alkanol in a well ventilated laboratory.For the the preparation of acid chlorides always lead any gases produced down into a sinkwith the tap running and distil the mixture from a water bath not with direct heat.

Phosphorus trichloride oxide (Phosphorus oxychloride, phosphorylchloride)

T, C (Y12) (N13) S6 FC

Phthalic anhydride see Benzene-1,2-dicarboxylic anhydridePicric acid see 2,4,6-trinitrophenolPotassium F, C Teacher/Technician Schools are advised not to keep large quantities of the metal and stocks must be checked on

a regular basis. Old stock of this metal that have started to go yellow due to the productionof super oxide may explode when cut. It should be destroyed by adding it a small piece at atime to butan-1-ol, butan-2-ol or 2-methylbutan-2-ol. Potassium should never be burnt in pure oxygen or chlorine. Potassium reacts explosivelywith ice. Alloys of potassium with sodium should not be prepared as they spontaneouslyinflame in air.

Y12 N13 S6 The fusion test with 1,1,1-trichloroethane and other halogenated hydrocarbons is dangerousand should not be attempted. Alternatives are the Shoenig Oxygen flask method orMiddleton's Test.

Potassium amide(Potassamide)

C Not generally recommended Not recommended for use in schools.

Potassium bisulphate see Potassium hydrogensulfatePotassium bromate(V) T, O, Carc 2 Y12 N13 S6 The toxicity is mainly via ingestion and handling dilute solutions presents negligible risk.Potassium carbonate Xn Y7 N8 S1


Potassium chlorate(V) (chlorate)

O, Xn Y12 N13 S6 Avoid concentrated sulfuric acid as unstable chlorine dioxide will be formed which will giverise to a serious risk of explosion. Do not allow solutions to dry on wood, paper or clothing as these may ignite at a later time.

Teacher/Technician Thermal decomposition with and without trace of MnO2. Need for cleanliness. Do notreturn unused chlorate(V) to jar and replace lid immediately to exclude dust. This compound can react violently with reducing agents and should not be mixed with thefollowing:

Not generally recommended (i) sulfur or sulfidesditto (ii) ammonium saltsditto (iii) phosphorusditto (iv) 2,4,6- trinitrophenol (picric acid)ditto (v) fine metal powders such as aluminium and magnesiumditto (vi) 3,4,5- trihydroxybenzoic acid (gallic acid.)

ditto (vii) fuels such as sugar and hydrocarbons.

Y12 N13 S6 Use 0.05M solutions in redox reactionsY12 N13 S6 Solutions of chlorates(V) produced, eg of potassium potassium or chlorate produced during

determination of solubility/ temperature curves should not be allowed to dry out. The solidmay be recovered by recrystallisation at the end of the measurement, but this should not beused for heating experiments.

Potassium chlorate(VII) (perchlorate)

O, Xn Not generally recommended Not recommended for use in schools Need for cleanliness. Do not return unusedchlorate(V) to jar and replace lid immediately to exclude dust

Teacher/Technician Preparation of solutions.Y12 N13 S6 Use of 0.05M solutions in test-tube redox reactions.

Do not allow solutions to dry on wood, paper or clothing as these may ignite at a later time.This material is produced in the disproportionation reaction of potassium chlorate(V). If thesolid is crystallised out it should not be stored for use in other experiments.

Potassium cyanide Not generally recommended Not recommended for use in schools solid T+, N Teacher/Technician FC solution > 7% T+, N Teacher/Technician

1 to 7% T, N (Y12) (N13) (S6)

0.1 to 1% Xn (Y12) (N13) (S6)

FC In exceptional circumstances small amounts of dilute solutions can be used by experiencedteachers. Solutions of cyanides are sometimes used in advanced biological experiments oras a masking agent in analytical work. It is safest if ready prepared solutions are bought inas and when they are needed and used only by staff.


Potassium dichromate(VI) For preparations involving oxidation and titrations use manganate(VII) where possible. Useon as small a scale as is reasonable. Avoid creating dust - this is easy owing to the largecrystals and avoid creating aerosols from solution, eg by vigorous gas evolution fromelectrolysis, etc.

Y12 N13 S6

solid & solutions >7% (> 0.23M) T+, N, Carc 2(inhal), Sen Y12 N13 S5

Oxidation of alcohols - ensure all the solid has dissolved and add the acidified dichromatesolution dropwise whilst mixing the contents of the flask thoroughly.

0.5% to 7% (0.017 to 0.23M) T, Carc 2(inhal), Sen Y10 N11 S3 Use on as small a scale as possible. 0.1% to 0.5% (0.003 to 0.017M) T, Carc 2(inhal) Y9 N10 S2Insoluble solids T, Carc 2(inhal) Not generally recommended Chromate precipates should not be isolated and dried in experiments. Potassium fluoride solid T Teacher/Technician solutions, 3 to 25% (0.5 to 4M) Xn Y12 N13 S6Potassium hexacyanoferrates(II) (ferrocyanide)

Forms explosive mixtures with nitrites and gives extremely toxic hydrogen cyanide if heatedwith acids. Do not heat the solid.

solid Low hazard Y12 N13 S5 solution Y9 N10 S2 Detection of iron(III) ions.Potassium hexacyanoferrates(III) (ferricyanide)

May explode with ammonia, forms explosive mixtures with nitrites and gives extremelytoxic hydrogen cyanide with acids. Do not heat the solid.

solid Low hazard Y12 N13 S5 solution Y9 N10 S2 Detection of iron(II) and use in Ferroxyl indicator for corrosion testing.Potassium hydrogensulfate (bisulphate) solid C Y9 N10 S5 solution > 10% (0.7M) C (Y7) (N8) S2 5% to 10% (0.4 to 0.7M) Xi Y7 N8 S1Potassium hydroxide solid or melt C (Y12) (N13) (S6)

solutions > 25% ( > 5M) C (Y12) (N13) (S6) 5 to 25% ( 1 to 5M) C (Y12) (N13) (S6) 2 to 5% (0.4 to 1M) C Y9 N10 S3 0.5 to 2% (0.1 to 0.4M) Xi Y9 N10 S1

Eye protection must be worn at all times when using this material no matter how dilute thesolution involved. Solutions > 1M cause severe burns. A corrosive aerosol is often givenoff when solution is being prepared and good ventilation or a fume cupboard is needed.. Most reactions below Y9/S4 can be carried out with solutions weaker than 0.4M and belowS2/ Y8, solutions with lower concentrations (0.1M) are adequate for most work. Wheremore concentrated solutions are required, eg for soap making then close supervision isneeded.

Potassium iodate(V) O, Xn Y12 N13 S6 Reacts violently with aluminium, magnesium, carbon, sulfur, phosphorus or organicmaterials. Potassium iodate has also been known to react violently with disulfate(VI)(metabisulfite) if the dry solids are mixed and water then added. The reaction withconcentrated sulfuric acid can be carried out on a test tube scale, the residue being disposedof by mixing with a large volume of water.


Potassium manganate(VII) (permanganate)

O, Xn, N Being a powerful oxidising agent it can cause ignition of (i) organic compounds - sugars, esters, aldehydes, esters, wood paper and (ii) reducing agents - metals, sulfur, phosphorus. With some of these there is an inductionperiod, eg with propane-1,2, 3-triol. Ammonia and ammonium compounds may produceexplosive salts when mixed dry.Acidified dilute hydrogen peroxide can be used to clean stains left by manganate(VII), butconcentrated hydrogen peroxide must not be used.

(Y7) (N8) (S1) (FC) Heating solid is in a tube; as a very fine dust is produced; use a loose fitting plug of rocksilor mineral wool or Superwool or carry out in a fume cupboard.

(Y12) (N13) (S6) FC Large scale preparation of chlorine. Manganate(VII) forms an explosive mixture withconcentrated sulfuric acid or phosphoric acid and if the solid is being used to preparechlorine gas it is essential to double-check that the acid used in the reaction is hydrochloricacid. The reaction is very vigorous and the hydrochloric acid must be added very slowly;alternatively cover the solid iwith water. It is best not to use sulfuric acid for drying the gas.Consider the use of Sodium chlorate(I) as alternative preparation.

Teacher/Technician Demonstration or reaction with propane-1,2,3-triol.Potassium nitrate(V) (nitrate)

O Nitrates form explosive mixtures with aluminium, magnesium, sodium, potassium and othermetals plus ammonium salts, cyanides, sulfides, thiosulfates, and ethanoates. If, in thethermal decomposition of a nitrate, oxygen is being tested for, care needs to be taken that thesplint does not drop into the molten mass. See also entry on Nitrates. Under supervisionwith all students.

Y11 N12 S5 Y7 and S1 can use for solubility experiments and Y9 for heating.Y12 N13 S6 Testing or reactions with concentrated sulfuric or phosphoric acids.

Potassium nitrate(III) (nitrite)

O, T, N Y12 N13 S6 React with acids to produce nitrogen monoxide which gives toxic nitrogen dioxide in air.The solid is dangerous with ammonium salts, cyanides, and thiosulfates. It should not bereacted with phenol which forms an explosive mixture.

solution > 5% ( > 0.6M) T Y12 N13 S6 1% to 5% (0.1 to 0.6M) Xn Y9 N10 S3Potassium perchlorate see Potassium chlorate(VII)Potassium permanganate see Potassium manganate(VII)Potassium peroxodisulfate(VI) (persulphate)

O, Xn, Sen Y12 N13 S6 Can react violently with reducing agents, especially metal powders, organic compounds, andcan cause ignition of paper, cloth and wood. Store out of direct sunlight. Decomposesslowly and pressure may build up in container - open carefully. Short shelf life.

Potassium phosphate (tribasic) Xi Y7 N8 S2Potassium sulfide C, N Y11 N12 S5 (FC) Produces very toxic, extremely flammable hydrogen sulfide with acids. Use 0.2M or weaker

solution for metal sulphide precipitation reactions.


Potassium thiocyanate solid Xn Y12 N13 S4

Dangerous with concentrated sulfuric acid when the gas carbonyl sulfide is produced. Diluteacid with boiling has the same effect but very slowly.

solution Low hazard Y9 N10 S2 The very dilute solution provides very little hazard if used in the test for iron(III) but thematerial should not be evaporated to dryness.

Procion Direct dyes Sensitiser Two types of Direct dyes. Most are sensitisers by skin contact. HE types need a dyeingtemperature of 80ºC. MX types have the advantage of being fixed at the low temperature of40ºC but two of the MX range are respiratory sensitisers (Orange MX-2R and Yellow MX-R). With the latter two extra care is needed to avoid raising dust. Where possible purchase"de-dusted" dyes.

solid Xi, Sen Teacher/Technician (FC) Technicians should make solutions for reactions in a fume cupboard. dilute solution for dyeing Low hazard Y7 N8 S2 Solutions are safe for all levels.Propanal F, Xi Y10 N11 S5 (FC)Propane cylinder F+ Not generally recommended Not recommended for use in schools except as source of piped burner supply.Propanoic acid > 25% (4M) C Y9 N10 S4 (FC) 10 to 25% (1.5 to 4M) XiPropan-1-ol and 2-ol(n-propanol and isopropanol)

F, Xi Y10 N11 S5 (FC) Always use a water bath for heating. Propan-2-ol will form peroxides; test old samples forpresence of peroxides (see ethoxyethane) and if treated to remove peroxides, useimmediately and do not store.In preparation of propanone by oxidation of propan-2-ol ensure the acidifieddichromare(VI) is added slowly with swirling or stirring between each addition.

Propanone(Acetone)

F, Xi (FC) The reaction with halogenated hydrocarbons such as trichloromethane can be vigorous aftera long induction period (Ethyl ethanoate provides a safer alternative for measurement ofintermolecular forces). Nitric acid reacts violently with propanone. Do not use as a solventfor oxidations by hydrogen peroxide or other peroxy compounds as propanone peroxideswill form. All heating must be done on a water bath.

(Y7) (N8) (S1) Chromatography eluting agent or a example of a solvent using small scale.Y11 N12 S5 Larger scale use as solvent and for properties of alkanones.

Propenamide (Acrylamide)

T, Carc 2, Sen Not generally recommended Polymerisation of the monomer is not recommended in schools. For DNA electrophoresisagarose works for most cases. If polyacrylamide is needed, purchase the gel in pre-polymerised sheets or slabs.

Propionaldehyde see PropanalPropionic acid see Propanoic acidPropyl acetate see Propyl ethanoatePropylamine, liquid F, C Y12 N13 S6 FC Butylamine provideds a less volatile and less flammable alternative.

solution 5 to 10% (ca.0.9 to 1.7M) Xi Y11 N12 S5 Suitable for test tube reactions. Dilute to 0.5M (approx. 4 cm3 made up to 100 cm3 )

n-Propyl bromide see 1-bromopropaneIso-Propyl bromide see 2-bromopropanePropyl chlorides see Chloropropanes


Propylene dibromide see 1,2-dibromopropanePropyl ethanoate (acetate)

F, Xi Y9 N10 S5 (FC)

n-propyl iodide see 1-iodopropaneProtactinium generator, preparation of see Uranium compoundsPyridine F, Xn Y12 N13 S6 FC No sources of ignition should be present.Pyrogallol see Benzene-1,2,3-triolQuinine Xn Teacher/Technician Cold tea provides a good alternative for taste bud tests. Quinol see Benzene-1,4-diolRadon generator see Thorium compoundsResazurin Xi Y9 N10 S2 Usually supplied in the form of tablets from which risk of exposure is negligible.Resorcinol see Benzene-1,3-diolSalicylic acid see 2-hydroxybenzenecarboxylic acidSalol see Phenyl 2-hydroxybenzenecarboxylateSaponin Xi Y9 N10 S3Screened methyl orange solution F Y7 N8 S4Sebacoyl chloride see Decanedioyl dichlorideSelenium and compounds T, N Not generally recommended An exhibition sample may be kept.Silicon tetrachloride Xi (Y12) (N13) (S6)

Silver nitrate, solid C, N Y12 N13 S6

solution >10% ( > 0.5M) C (Y7) (N8) S6 5 to 10% (0.3M to 0.5M) Xi Y9 N10 S2Smoking machineSodalime(equivalent to a mixture of sodium andcalcium hydroxides)

C (Y7) (N8) (S3)

Sodamide C Not generally recommended Not recommended for use in schools.


Sodium F, C (Y12) (N13) (S6) Reacts explosively with acids. Forms explosive mixtures with poly-halogenatedhydrocarbons. Violent reactions with bromine liquid, iodine, mercury and sulfur. Theaddition of water to sodium (rather than the usual reaction of adding a small piece to a largevolume of water) is explosive due to the production of sodium oxide and sodium hydride andis much too dangerous to be tried in schools. In combustion reactions with oxygen and chlorine only small pieces should be used. In thereaction with water first chill the water with a few ice cubes and only use a small piece ofsodium. The sodium must not be trapped in an attempt to collect the hydrogen unless anapparatus specifically designed for the purpose is used. Alloys of sodium with potassiumspontaneously inflame in air. For the sodium fusion test use very small amount (0.2g) of sodium with 0.1g of solid and asafety screen or use Schoenig Oxygen Flask method.

Sodium amalgam F, T, C, N Y12 N13 (S6) If mercury is used as the electrode in the electrolysis of sodium chloride solution theamalgam produced must be totally reacted before the mercury is added to the stock of 'dirty'mercury saved for purification. This can be achieved by covering the material with dilutehydrochloric acid and leaving standing for several days (hydrogen is evolved, so carry outin a well ventilated place). Alternatively add water and an iron nail. If amalgam is prepared for preparative reductions, this must be done by the teacher ortechnician.

Sodium azide T+, N Not generally recommended Avoid use if at all possible. Small amounts of dilute solutions are sometimes used inanalytical procedures. Take care with disposal as it forms explosive azides with heavymetals - drains may contain copper or even lead parts! Contact with acid liberates a verytoxic gas.

Sodium bisulfate see Sodium hydrogensulfateSodium bisuphfite see Sodium hydrogensulfate(IV)Sodium borohydride see Sodium tetrahydroborateSodium carbonate Xi Y7 N8 S1Sodium chlorate(I) (hypochlorite) solution concentrated; >10% available chlorine C (Y9) (N10) S5

Dangerous with conc. sulfuric acid. Forms explosive products with ammonium salts,methanol, and amines. Gives chlorine with acids. If used to prepare chlorine 5M HClshould be used. Sodium chlorate (I) is unstable in sunlight and should be stored in acupboard. As the solution gives off oxygen during storage it should be assumed that therewill be a pressure release on opening. The problem is worse in summer and accelerated bysome transition metal compounds.

dilute, 0.5% to 10% available chlorine Xi (Y7) (N8) (S1) Solutions of chlorine can be prepared on a small scale by adding a few cm3 of 1Mhydrochloric acid to a few cm3 diluted sodium chlorate(I) solution (The commercial 14%solution should be diluted tenfold beforehand by the teacher or technician.)

Sodium chlorate(V) (chlorate)

O, Xn Y12 N13 S6 Avoid concentrated sulfuric acid as unstable chlorine dioxide will be formed which will giverise to a serious risk of explosion. Do not allow solutions to dry on wood, paper or clothing as these may ignite at a later time.

Teacher/Technician Thermal decomposition with and without trace of MnO2 Need for cleanliness. Do notreturn unused chlorate(V) to jar and replace lid immediately to exclude dust.


This salt can react violently with reducing agents and should not be mixed with thefollowing:

Not generally recommended (i) sulfur or sulfidesditto (ii) ammonium saltsditto (iii) phosphorusditto (iv) 2,4,6- trinitrophenol (picric acid)ditto (v) fine metal powders such as aluminium and magnesiumditto (vi) 3,4,5- trihydroxybenzoic acid (gallic acid.)ditto (vii) fuels such as sugar and hydrocarbons.

Y12 N13 S6 Use 0.05M solutions in redox reactionsY12 N13 S6 Solutions of chlorates(V) produced, eg of potassium potassium or chlorate produced during

determination of solubility/ temperature curves should not be allowed to dry out. The solidmay be recovered by recrystallisation at the end of the measurement, but this should not beused for heating experiments.

Sodium cobaltinitrite see Sodium hexanitrocobaltate(III)Sodium chromate(VI) For preparations involving oxidation and titrations use manganate(VII) where possible. Use

on as small a scale as is reasonable. Avoid creating dust - this is easy owing to the largecrystals and avoid creating aerosols from solution, eg by vigorous gas evolution fromelectrolysis, etc.

- oxidation of alkanols Y12 N13 S6


Ensure all the solid has dissolved and add the acidified dichromate solution dropwise whilstmixing the contents of the flask thoroughly.

0.5% to 7% (0.017 to 0.23M) T, Carc 2(inhal), Sen Y10 N11 S3 Use on as small a scale as possible. 0.1% to 0.5% (0.003 to 0.017M) T, Carc 2(inhal) Y9 N10 S2Insoluble solids T, Carc 2(inhal) Not generally recommended Chromate precipates should not be isolated and dried in experiments. Sodium dichromate(VI) For preparations involving oxidation and titrations use manganate(VII) where possible. Use

on as small a scale as is reasonable. Avoid creating dust - this is easy owing to the largecrystals and avoid creating aerosols from solution, eg by vigorous gas evolution fromelectrolysis, etc.

- oxidation of alkanols Y12 N13 S6


Ensure all the solid has dissolved and add the acidified dichromate solution dropwise whilstmixing the contents of the flask thoroughly.

0.5% to 7% (0.017 to 0.23M) T, Carc 2(inhal), Sen Y10 N11 S3 Use on as small a scale as possible. 0.1% to 0.5% (0.003 to 0.017M) T, Carc 2(inhal) Y9 N10 S2Insoluble solids T, Carc 2(inhal) Not generally recommended Chromate precipates should not be isolated and dried in experiments. Sodium dithionite Xn (Y9) (N10) (S3) Supply the material in solution for class use. Can cause fire if added to a small amount of

water. Weigh out in dry beaker. Sulfur dioxide may be evolved.


Sodium dodecyl sulfate (lauryl sulphate)

Xn Y9 N10 S3

Sodium ethanedioate (oxalate) solid Xn Y12 N13 S6 solution ( > 0.4M) Xn Y9 N10 S5Sodium fluoride solid T Teacher/Technician solutions 3 to 25% (0.5 to 4M) Xn Y12 N13 S6Sodium hexanitrocobaltate(III) (Sodium cobaltinitrite)

O, Xi Y12 N13 S6

Sodium hydride F TT TT (S6) Reacts violently with water to give off hydrogen. Can ignite in moist air. Sodium hydrogensulfate (bisulphate) solid Xi (Y9) (N10) S3 solution 5 to 10 % (0.5 to 1M) Xi (Y7) (N8) S2 < 5% (< 0.5M) Y7 N8 S1Sodium hydrogensulfate(IV), solid (hydrogensulphite or bisulphite)

Xn (FC) Sulfur dioxide is readily evolved with dilute acids.

solution > 5% Xn (Y10) ((N11) (S4) Use in test tube redox work.(Y7) (N8) (S3) As very dilute solution of sulfur dioxide.

Sodium hydroxide solid or melt C (Y12) (N13) (S6)

solutions > 25% ( > 5M) C (Y12) (N13) (S6) 5 to 25% ( 1 to 5M) C (Y12) (N13) (S6) 2 to 5% (0.5 to 1M) C Y9 N10 S3 0.5 to 2% (0.1 to 0.5M) Xi Y7 N8 (S1)

Eye protection must be worn at all times when using this material no matter how dilute thesolution involved. Solutions > 1M cause severe burns. A corrosive aerosol is often givenoff when solution is being prepared and good ventilation or a fume cupboard is needed. Most reactions below Y9 or S4 can be carried out with solutions weaker than 0.4M. BelowS2/ Y8 levels 0.1M solutions are adequate for most work. Where more concentratedsolutions are required, eg for soap making, then close supervision is needed.

Sodium hypochlorite see Sodium chlorate(I)Sodium lauryl sulphate see Sodium dodecyl sulfateSodium polytrioxovanadate(V) (metavanadate)

T, N Y12 N13 S6 Ammonium metavanadate provides a cheaper alternative for investigating the severaloxidation states of vanadium.

solution > 5% ( > 0.4M) T 0.5 to 5% (0.04 to 0.4M) Xn


Sodium nitrate(V) (nitrate)

O Nitrates form explosive mixtures with aluminium, magnesium, sodium, potassium and othermetals plus ammonium salts, cyanides, sulfides, thiosulfates, and ethanoates.If, in the thermal decomposition of a nitrate, oxygen is being tested for, care needs to betaken that the splint does not drop into the molten mass. See also entry on Nitrates. Allstudents need to be supervised

Y11 N12 S5 Y7 and S1 can use for solubility experiments and Y9 for heating.Y12 N13 S6 Testing or reactions with conc sulfuric or phosphoric acids.

Sodium nitrate(III) (nitrite)

O, T, N Y12 N13 S6

solution > 5% ( > 0.7M) T Y12 N13 S6 1% to 5% (0.14 to 0.7M) Xn Y9 N10 S3

Reacts with acids to produce nitrogen monoxide which gives toxic nitrogen dioxide in air.The solid is dangerous with ammonium salts, cyanides, and thiosulfates. It should not bereacted with phenol which forms an explosive mixture.

Sodium nitroprusside see Sodium pentacyanonitrosylferrate(II)

Sodium oxalate see Sodium ethanedioate

Sodium pentacyanonitrosylferrate(II) (nitroprusside)

T (Y12) (N13) S6 Toxic by inhalation and ingestion. Do not decompose by heat.

solution > 25% ( > 0.84M) T 3 to 25% (0.1 to 0.84M) XnSodium peroxide O, C (Y12) (N13) (S5) Combustible materials may ignite spontaneously especially if damp. The reactions with

ethanoic acid and ethanoic anhydride are explosive. It forms an explosive mixture withtin(II) chloride. Reacts with water to give sodium hydroxide.

Sodium sulfide solid C, N Y12 N13 S6 FC Reacts with acids to give toxic hydrogen sulfide. solution XiSodium tetrahydroborate (borohydride)

F, T Teacher/Technician This can be used in methanol or even in cold water for reduction of alkanones and alkanalswhereas the lithium aluminium hydride can ignite even in moist air and needs extremely dryethoxyethane.

Stannous salts see Tin(II) saltsStannic compounds see Tin(IV) compoundsStrontium F, C Teacher/Technician Handle with care.Styrene see PhenyletheneSulphanilic acid see 4-aminobenzenesulfonic acidSulfides of heavy metals (Y9) (N10) (S2) (FC) Use a fume cupboard if any reactions are to be investigated involving the use of acid as toxic

hydrogen sulfide is produced or if "simulated" or real sulfide ores are to be roasted (sulfurdioxide evolved). If choosing ores from the "field", choose carefully to ensure no metalarsenides are also present.


Sulfur F Y7 N8 (S2) (FC) Sulfur burns to give the toxic sulfur dioxide gas. All reactions that involve the possibility ofsulfur igniting should preferably be carried out in a fume cupboard. When heating sulfuralone or with iron in a test-tube in an open laboratory, use a loose plug of mineral wool orSuperwool to minimise the escape of the sulfur vapour and its ignition. See entry on Sulfurdioxide.The reaction of sulfur with oxidising agents such as chlorates must not be carried out inschools.The reactions with magnesium, aluminium or more reactive metals are too violent andshould not be carried out.

(Y9) (N10) (S2) The reactions with copper and iron may be carried out provided safety screens are used.The reaction with zinc powder (avoid fine zinc dust) is possible provided small amounts areused and the mixture is not restricted in any way and safety screens are used.

Sulfur chlorides T, C, N (Y12) (N13) (S6) FC Reacts with water producing a range of sulfur compounds. The use of a fume cupboard isessential and supervision needded if students use the material.

Sulfur dichloride dioxide (Sulfuryl chloride)

C (Y12) (N13) (S6) FC Reacts slowly with cold water and rapidly with hot water to give toxic and corrosive fumesof sulfuric and hydrochloric acids.

Sulfur dichloride oxide (Thionyl chloride)

C (Y12) (N13) (S6) FC Irritating to respiratory system. Wear gloves. Considered to be more toxic than sulfurdioxide.

Sulfur dioxide Many students may be susceptible to asthma attacks which can be brought on by smallquantities of the gas. A warning should be issued before the experiment whenever there is apossibility of the gas being evolved in a reaction.

- canister T (Y12) (N13) (S6) FC The valves of canisters of sulfur dioxide should be checked and replaced regularly as theyare prone to corrode. The valve should not be screwed down too tight as this eventuallyproduces a hole too large for the valve to seal. The older aluminium canisters can no longerbe purchased. Rubber tubing that has been used for reactions involving the gas should bediscarded after use.

- preparation, large scale T Y12 N13 S6 FC - test tube preparation T (Y9) (N10) S3 (FC) - reaction rates with thiosulfate T Y10 N11 S4 Immediately a run is finished, greatly dilute with water and then wash to waste to minimise

the amount of sulfur dioxide escaping. When investigating the effect of temperature, do notheat solutions above 30 or 40ºC, but extend the range downwards with ice-chilled water.

- use of aqueous solution Xi (if 0.5 to 5%)C (if > 5%)

Y10 N11 S4 (FC) Supply a solution of the gas made by teacher or technician for use by pupils.Alternatively pupils prepare in test tube by adding a few drops of 1M sulfuric acid to a pinchof sodium sulfate(IV) in water.

Sulfuric acid The reactions with chlorates(V) and manganate(VII) produce spontaneously explosiveproducts. The reaction with sugar can produce large volumes of carbon monoxide and theproduct needs to be washed thoroughly before it is touched. The reaction with water is veryexothermic and solutions must be made by the addition of the acid to the water with mixing.

concentrated, (98%) (18M) C (Y12) (N13) (S6) The Charle's Law apparatus (glass U-tube with graduated limb) is more accurate than the useof a mercury bead trapped in a short length of sealed capillary tube, though the latter is safer.

( > 1.5 M) C (Y9) (N10) (S5) ( 0.5 to 1.5 M) Xi (Y7) (N8) (S2)


Sulfuryl chloride see Sulfur dichloride dioxideTellurium metal T Not generally recommended Keep as exhibition sample only.Tellurium compounds T Not generally recommended Not suitable for use in schools.Tetrachloromethane(Carbon tetrachloride)

T, N (Y12) (N13) (S6) FC It is difficult to obtain from suppliers on account of its ozone depleting properties. It mightbe possible to obtain it in order to show its unique properties, ie comparison of hydrolysis ofhalides across the periodic table or down Group IV. Do not use as solvent or in applicationswhere it is lost by evaporation. Use only in an efficient fume cupboard.Reactions with magnesium and aluminium are violent.

Thallium metal T+ Not generally recommended Not suitable for use in schools.Thallium salts T+, N Not generally recommended Not suitable for use in schools.Thiocarbamide (Thiourea)

Xn, N, Carc 3 Y12 N13 S6

Thiocyanates solid Xn Y12 N13 S5

Dangerous with concentrated sulfuric acid when the gas carbonyl sulfide is produced. Diluteacid with boiling has the same effect but very slowly. Explosive with several oxidisingagents.

solution Low hazard Y9 N10 S2 The very dilute solution provides very little hazard if used in the test for iron(III) but thematerial should not be evaporated to dryness.Cobalt thiocyanate paper sometimes recommended in place of cobalt chloride.paper.

Thionyl chloride see Sulfur dichloride oxideThorium compounds T, Radioactive TT TT XX Schools in Scotland are not permitted to hold thorium salts, but are recommended to instead

use the protactinium generator for half life measurement.Schools in England, Wales and Northern Ireland can apply to use thorium compounds aschemicals; however these count as open sources and the Ionising Radiation Regulations1999 (IRR) will require a thorough risk assessment to be made and the compounds used onlyin designated "Controlled Areas". In schools it will be very difficult if not impossible tomeet these requirements.

- Radon Generator (Y12) (N13) XX Maintained schools in England and Wales need approval from the DfES or WAG; the highercategory B is needed for thorium compounds other than in radon generators.

Tin(II) chloride (Stannous chloride)Tin(II) chloride- 2- water

CXi

Y10 N13 S5 Can form explosive mixture with oxidising agents such as nitrates and peroxides.

Tin(IV) chloride(Stannic chloride)

C Y12 N13 S6 FC Reacts with moist air and water to give fumes of hydrogen chloride. Wear nitrile gloves.Explosive mixture with turpentine.

Titanium(IV) chloride(Titanium tetrachloride)

C Teacher/Technician FC Violent reaction with water producing hydrogen chloride. Bottles of this material should beopened with caution, covering with a dry cloth as HCl gas may escape under pressure.

o-tolidine see 3,3'-dimethylbiphenyl-4,4'-diamineTollen's Reagent C Y12 N13 S5 Use a clean test tube. Make only as needed, heat on water bath just long enoughfor the

silver mirror to form; then discard the solution into a large volume of water and wash thetube out with dilute nitric acid. Do not store the solution and do not add excess solution orproduct of reaction to silver residues bottles.


Toluene see Methylbenzene1,1,1-trichloroethane(Methylchloroform)

Xn, N (Y12) (N13) S6 (FC) Existing stocks should only be used in ways which entail minimal evaporation. Itsmanufacture has been phased out as it is an ozone depleter. This liquid had been used as asafer solvent in applications where tetrachloromethane or trichloromethane were used. It should be treated with care. The reactions with metals such as magnesium, aluminium,sodium are violent or explosive.

2,2,2-trichloroethanediol (Chloral hydrate)

T Y12 N13 S6 FC

Trichloroethanoic acid(Trichloroacetic acid)

C, N (Y12) (N13) (S6) Do not heat, decomposition can produce a toxic gas.

solutions > 5% ( > 0.3M) C (Y12) (N13) (S6) 1 to 5% (0.06M to 0.3M) Xi (Y12) (N13) (S6)

Do not store solutions less than 30% for longer than necessary as such solutions arehydrolysed to give trichloromethane, hydrogen chloride, carbon dioxide and carbonmonoxide. This can build up a high pressure in a stoppered bottle.

Trichlorethene(Trichloroethylene)

T, Carc 2 (Y12) (N13) (S5) FC All handling where some vapour may escape must be done in a fume cupboard. This liquidhas been advocated as an alternative solvent for 1,1,1-trichloroethane and also fortetrachloromethane or trichloromethane. However it should be treated with care.The reactions with metals such as magnesium, aluminium, sodium are violent or explosive.Vigorous reaction with alkalis.Where possible substitute with cyclohexane, butyl ethanoate, Volasil, Lotoxane, etc.

Trichloromethane (Chloroform)

Xn, Carc 3 Y12 N13 S5 FC This material should only be used in an efficient fume cupboard and where there is nosuitable alternative available and never as a solvent. The reactions with aluminium andmagnesium are violent and those with sodium, potassium and lithium explosive. Alkalis inthe presence of alcohols or ketones show violent reactions. Trichloromethane should neverbe heated to a high temperature in air as thermal decomposition can cause the production ofthe very toxic carbonyl chloride (Phosgene).The interaction with propanone to show intermolecular forces may become violent a longtime after mixing if traces of base are present. Ethyl ethanoate can be used in place of thepropanone. Find alternatives where possible, eg- for extraction of caffeine dichloromethane is a suitable, but should be used in a fumecupboard.- as second solvent for 2-D paper chromatography of plastid pigments replacetrichloromethane/pet ether with ethoxyethane/pet ether.

3,4,5-trihydroxybenzene carboxylic acid(Gallic acid, 3,4,5-trihydroxybenzoic acid)

Xi Y12 N13 S6

Triiodomethane(Iodoform)

Xn Y12 N13 S5 (FC) This is usually encountered in the "Iodoform Test" for activated methyl groups. Use dropscale; propanone reacts quickly, but some other compounds require some heating. Use theminimum to avoid excessive triiodomethane being driven off.


Trimethylamine F+, C (Y12) (N13) (S6) FC 45% solution in water (7M) F+, C (Y12) (N13) (S6) FC 24% solution in water (4M) F, C Y12 N13 S6 FC

For most reactions a 0.5M solution or weaker is adequate to show properties.

5 to 10% (approx 1M to 2M) Xi Y12 N13 S62,4,6-trinitrophenol (Picric acid)

This material is explosive and if stocks of the material need to be kept in schools they mustbe checked regularly to ensure the material is kept very damp.

solid E, T Teacher/Technician The material should only be used in solution. Reactions of this material with alkali andchlorates should not be tried.

saturated solution (approx. 1%) (Y12) (N13) (S6)Turpentine Xn, F-, N Being obtained from natural sources the composition can be variable. Some batches may

contain sensitisers (skin and respiratory).Teacher/Technician FC The reaction with chlorine should be carried out in a fume cupboard.Y12 N13 S6 (FC) Investigating natural oils.

Uranium T+ NR NR XX The metal is radioactive and very toxic, especially by inhalation. If used avoid any processwhich generates dust. Its use in Scotland is banned; to use in the rest of the UK approvalneeds to be sought from DfES, WAG or DENI. Not suitable for use in schools.

Uranium compounds, solid T+, N Teacher/Technician 100 g of uranyl nitrate may be kept by schools authorised under Category C of the DES AM1/92, SEED Circular 1166 and the DENI Guidance "Use of ionising radiations in educationalestablishments (1986)" There are no discrete Welsh Directives in order to prepareprotactinium generators. Those working in Categories A and B may hold more.

- Protactinium generator, preparation ofsolution

T+, C, N Teacher/Technician For further details see Topic 19 in Topics, SSERC Explanatory Notes to accompany Circular1166, SSERC Bulletins 158 & 199 and CLEAPSS Guide L93.

Use of protactinium generator (Y12) (N13) (S6)Vanadium(V) oxide(Vanadium pentoxide)

T, N Y12 N13 S6 If being used to demonstrate the contact process ensure no dust escapes. If the "catalystchamber" (eg, combustion tube) is already filled with vanadium(V) oxide pellets, continue touse it, but do not remove the pellets. Otherwise use platinised ceramic wool.

Vanadium(V) salts solid T, N Y12 N13 S6 solution T (Y9) (N10) S6Vinyl chloride monomer see ChloroetheneWij's solution(glacial ethanoic/chlorine/iodine)

F-, T, C Y12 N13 S6

Xylene cyanol solid Xi Y12 N13 S6 solution (alcohol) F Y9 N10 S2Zinc, powder Fhydrogen preparation (test tube scale) F (Y7) (N8) (S1) (large scale) Teacher/Technician

The dust reacts violently with sulfur, iodine, manganese (IV) oxide, potassium chlorate(V)and in general with oxidising agents. For reactions with iodine use coarse powder. Impuregranulated zinc is best for hydrogen preparation. Zinc metal is of low toxicity, but zincoxide fume from burning is harmful; only burn in a well ventilated room and only once ortwice on each occasion.


Zinc chloride C, N Y12 N13 S6Zinc chromate(VI) T, N, Carc 1 Not generally recommended Not suitable for use in schools. The solid is not recommended for use in schools. The

production of a precipitate of zinc chromate on a small scale does not present a hazardprovided it is not filtered off and dried.

Zinc iodide (anhydrous) C, N Y12 N13 S6

Zinc nitrate O, Xi Y9 N10 S3 Ignites combustible materials; violent reactions with metals and reducing agents. Toxicnitrogen dioxide evolved on heating. See Nitrates.

Zinc sulfate Xi, N Y7 N8 S1Zinc sulfide Xn, N (Y8) (N9) (S2) FC Can liberate very toxic hydrogen sulfide on acidification.

If used as a substitute for Zinc Blende ore; roasting will produce much toxic sulfur dioxide.Use fume cupboard for this activity.

Topics in Safety, For abbreviations see Introduction · with alcohol, hydrocarbons and...

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