School Science Lessons
Please send comments to:

Chemistry P
Table of Contents
p-Aminobenzoic acid (PABA), Sunscreens and sun-protective clothing:
19.7.4 (See: 6.)
p-, photography developer
Pachycarpine, C15H26N2
Pachypodol, C18H16O7
Packaging gases, propellants, food additives: 19.4.22
See: Packaging (Commercial)
Paclitaxel, C47H51NO14
Paeonol, C9H10O3
Paint, Lead paint
Paint, Red lead, Pb3O4, lead (II/IV) oxide
Paints, safety advice for paints and paint strippers: 19.6.1
Palladium, Pd
Palm kernel oil: 19.2.11 (Table)
Palm oil: 19.2.11 (Table)
Palmatine, C21H24NO4+
Palmitic acid
Palmitic alcohol
Palmityl alcohol
Pampl's insect fixing solution, Prepare: 4.13
Pantothenic acid, C9H17NO5, vitamin B5
Papanicolaou stain: 3.33
Papaverine, C20H21NO4
Paper-making: Soda cellulose
Paper, Cyperus papyrus, papyrus, flat sedge, Cyperaceae (Greek: papuros)
Paper chromatography, Separate by chromatography, mixed inks: 3.24.1
Paper chromatography, Separate by chromatography, green leaf pigments: 3.24
Paper clips and rusting: 5.5.13
Paper towels, Separate with paper towels: 3.28
Parabens :
Paracetamol, C8H9O2, acetaminophen,
Paracresol, p-cresol (CH3)C6H4(OH), Cresol
Paradichlorbenzene, Reactions of chlorine with benzene: 13.4.6
Paraffin oil, kerosene
Paraldehyde, C6H12O3
Paramethyl red, C15H15N3O2: 29. (indicator)
Paranitrophenol, C6H5NO3: 30 (indicator)
Paraquat, C12H14N2+2: 16.7.4 (herbicide)
Parchment, treated animal skin (parchment, French: parchemin, pergumin, writing material)
Paris Green, Copper (II) acetoarsenite
Parthenolide, C15H20O3
Particles, matter as particles, size of particles: 3.0.0
Parts per million, Concentration, parts per million, 1 ppm = 1 mg per litre: 3.7.1
Pascal, SI, CGS, FPS., metric conversion: 3.12.0 (See: pressure, stress)
Pastes, Prepare glues and pastes, adhesives, gums: 9.0.0
Pasteurization and UHT (Ultra High temperature) of milk: 19.3.12
Pasteurized milk test: 16.1.11
PBDE, pentabromodiphenyl ether, C12H5Br5O: 16.14.1
PCBs, Dioxins, Agent orange: 16.14.0
PCBs, Polychlorinated biphenyls: 3.7.13
Peanuts (groundnuts)
Peak oil, Fossil fuels: 37.32.2
Pegmatite: 35.21.3 (Geology)
Peimine, C27H45NO3
PEITC, phenethyl isothiocyanate, C9H9NS Peltier effect (supercooled water)
Pencil, "Lead pencils", "Aquadag": 35.41.4
Pencil sharpener galvanic cell: 33.84.7
Penicillium, penicillin: 9.3.0
Pennyroyal oil (Mentha pulegium)
Pentachlorophenol, C6HCl5O (PCP), Organochlorine compounds: 16.3.0
Pentane, C5H12
Pentobarbital sodium salt, Barbiturates: 11.11.7
Pentose, 5 C pentose
Pentyl, -C5H11
Pepper, black pepper, betel pepper
Pepsin, Digestion in the stomach, reaction of pepsin: 9.221
Peptides, polypeptides
Peptone: Proteins
Peptone, Prepare vinegar bacteria solution: 9.2.22
Percentage solutions, %: 5.1.11
Perchlorates, ClO4-
Perchloric acid, HClO4, Not permitted in schools
Perfluorooctanoic acid (PFOA), C8HF15O2: 16.14.2
Perfluorooctanesulfonic acid (PFOS), C8HF17O3S, : 16.14.3
Perfume, Volatility of different liquids: 3.7
Perfumes and smells: 19.7.1 (cosmetics)
Periclase, MgO: Magnesium oxide
Peridinin, C39H50O
Perilla ketone, C10H14O2
Perillaldehyde, C10H14O
Perillartine, C10H15NO
Perillene, C10H14O
Perillyl alcohol, C10H16O
Perindopril, C19H32N2O5, "Coversyl", ACE (angiotensin converting enzyme), blood pressure inhibitor
Periodic acid, H5IO6
Periodic Table
Perlite, Obsidian:
Perlon plastic, Nylon polyamide:
Permalloy bar:
Permanent wave, Permanent crease solution: 19.5.6 (hairdressing)
Permanganate ion, MnO4-
Permanganates, hazards: 3.7.12
Permeate (cheese, milk)
Permethrin, C21H20Cl2O3, "Nix", 4 stereoioimers, medication and insecticide, treat scabies and lice
Perovskite, calcium titanate mineral, CaTiO3, used in newer solar cells
Peroxide ion: O22-
Peroxides, Hazards: 3.7.13
Persistence: 16.18.6 (pesticides and weedicides)
Peru balsam: 2.6 (mounting medium)
Perthite: Feldspars (See: Group 1. Alkaline feldspars)
Pesticides: 16.1.0
PET, Polyethylene terephthalate, Birefringent clear plastics: 27.189
PETE, Plastics recycling code: 3.5.3
Pethidine, Morphine and derivatives: 11.11.14
1.31 Petri dish
See: Dishes Petri Dishes, (Commercial)
Petrolatum, "Vaseline"
PFOA, C8HF15O2, Perfluorooctanoic acid: 16.14.2
PFOS, C8HF17O3S, Perfluorooctanesulfonic acid: 16.14.3
pH tests
Phase, Continuous phase / outer phase: 7.9.15
Phellandrene, C10H16
Phenanthroline, C12H8N2, 1, 10-phenanthroline
Phenethylamine, C8H11N
Phenethylamine group of alkaloids: 16.3.18
Phenethyl isothiocyanate (PEITC), C9H9NS
Phenetole, ethoxybenzene, use fume cupboard or < 10 g in cross ventilation, Toxic by all routes
Phenidone, 1-phenyl-4-methyl-3-pyrazolidone, photography developer, use solution < 20%, Harmful
Phenobarbital, Barbiturates: 11.11.7
Phenol, C6H5OH, carbolic acid: 16.1.0
Phenol red, C19H14O5S: 28 (indicator)
Phenolic acids:
Phenolic compounds: 16.1.0
Phenolphthalein, C20H14O4: 27 (indicator)
Phenothiazine, PTZ, C12H9NS,
Phenoxyethanol, 2-Phenoxyethanol, C8H10O2, colourless, oily, bactericide, sunscreens, cosmetics
Phenyl group, C6H5-
Phenylamine, C6H5NH2
Phenylalanine, C9H11NO2
Phenylamine, C6H5NH2, aniline, aminobenzene
Phenylpropanolamine, C9H13NO
Phyllodulcin, C16H14O5
Phillyrin, C27H34O11
Phloroglucinol, C6H3(OH)3
Phloxine B, antibacterial fluorescent dye (2, 4, 5, 7-Tetrabromo-4, 5, 6, 7-tetrachlorofluorescein disodium salt)
Acid Red 92, C20H2Br4Cl4Na2O5
Phosgene, carbonyl chloride, CoCl2: 3.39.2
Phosphatidylcholine group, Lecithins:
Phosphine, PH3
Phospholipids (phosphoglycerides):
Phosphoric acid, H3PO4
Phosphorus, P
Phosphorus compounds
Photochemical reactions
Phthalates: 3.0.4
Phthaleins, Fluorescein:
Phthalic acid, C6H4(COOH)2:
Phthalic anhydride, C6H4(CO)2O:
Phthalides lactone:
Phyllodulcin, C16H14O5
Physics, Laboratory safety for physics teaching: 7.0
Physical changes and chemical changes: 7.1.6
Physical hazards: 4.0.0 (Draft Australian criteria for the classification of hazardous chemicals)
Physcion, C16H12O5
Physostigmine, C15H21N3O2
Phytochemicals: 16.3.1
Phytoene, C40H64
Phytofluene, C40H62
Piceatannol, C14H12O4
Piceid, C20H22O8
Picric acid (NO2)3C6H2OH
Picrocrocin, C16H26O7
Picrotoxin, C30H34O13
PIDCP, Tests for vitamin C: 9.143 (See 1.)
Pigments: Dyes
Pigments: Plant pigments
Pilocarpine, C11H16N2O2
Pindone, C14H14O3:
Pinene, C10H16
Ping-pong ball, Ignite a celluloid ping-pong ball:
Pinitol, C7H14O8
Pinocamphone, C10H16O
Piped gas, laboratory gas, "lab gas", household gas
Piperidine, C5H11N
Piperine, C17H19NO3
Piperitone, C10H16O
Pipernonaline, C21H27NO3
Piperonyl butoxide, C19H30O5:, insecticide
Pipettes, Handling and transferring chemicals: 3.4.10 (Safety)
Pipettes, Danger of using pipettes in the laboratory: 1.25 (Safety)
See: Pipettes (Commercial)
Pitchblende, Uraninite: 35.20.46 (Geology)
pKa, Strong and weak acids:
Placer deposits: 35.3.03 (Geology)
Plagioclase feldspar, NaAlSi3O8, CaAl2Si2O8, Feldspars, 35.15.0 (Geology)
Plant, plants
Plant pigments
Plastics, Polymers and plastics: 3.0
Plastics recycling code: 3.5.3
See: Plastic ware (Commercial)
Plaster of Paris, CaSO4.H2O,
Plasticine, modelling clay
Plating, Electroplating: 15.1.0
Platinum, Pt
Pleuran, β-1, 3- and β-1, 6-glucan, oyster mushroom, Pleurotus ostreatus
Plumbagin, C11H8O3
Plutonium, Pu
PMMA, para-Methoxymethamphetamine, dangerous stimulant drug, "Dr Death"
Podophyllotoxin, C22H22O8
Polymethyl methacrylate, [CH2C(CH3)CO2CH3)]n: 3.7.24
Protopine, C20H19NO5
Poisons and First Aid: 3.10.0 (Table)
Poisons, Chemical Pesticides: 16.8.5
Poisson's ratio, v: 34.5.06
Polar covalent bonds: 3.01.2
Polarization, Polaroid film: 27.9.0
Pollution, Environmental chemistry: 18.0.0
Pollution, Environmental pollution: 34.9.0
Polonium, Po
Poly- 3.0 Polymers and plastics
Pools, Swimming pool chemistry: 18.0.0
Porcelain, laboratory items: 1.23
See: Porcelain ware (Commercial)
See: Porous Pots (Commercial)
Porphyrins, porphine:
Porphyry: (Geology)
Portland cement: 3.66.6
Potassium, K
See: Potassium Elements, Compounds, (Commercial)
Potato cell: 33.3.7 (electricity)
Potato dextrose agar solution, Prepare: 6.10
Potential energy, Chemical potential energy, enthalpy:
Potential energy, Energy from chemical reactions: 3.80
Poultices: 5.04.6 (herbal compresses)
Povidone, Polyvinyl pyrrolidene:
Pozzolana (puteolanum):
PP, Plastics recycling code: 3.5.3
PPG, aliphatic alcohol, viscosity-decreasing agent, solvent, fragrance ingredient
ppm, parts per million
ppt, parts per thousand, approx. g / kg of salt in solution, salinity sensors, total dissolved salt content in water
See: Salinity, (Commercial)
Practical, Chemicals standards
Practical work, Why are hands-on science activities so effective for student learning? Topic 2.0
Praseodymium, Pr
Precious metals
Prefixes and suffixes, chemistry: 9.0
Prefixes, SI prefixes, Decimal fractions and multiples: 6.3.5
Prenol, C5H10O
Prenylation, adding hydrophobic molecule to a protein so as to attach it to cell membrane
Preservatives, food additives: 19.4.23
Preserving food, Food preservation: 19.3.6
Pressure: 12.0.0 (Physics)
Prilled, pelletized, for machine-handled agricultural chemicals, e.g. priilled urea
Primary cell, Cells and batteries, dry cells: 33.3.0
Primary standard, Chemicals standards
Prions, "mad cow disease":
Proactinium, Pa
Procion yellow, Toxic. skin sensitizer, use 10% solution
Producer gas, air gas, similar to water gas, formed by passing air and steam over hot carbon.
Prohibited chemicals, Chemicals Not permitted in schools: 15.10.0
Proline, C5H9NO2 (Table of amino acids)
Proline, DNA codons
Promethazine, C17H20N2S
Promethium, Pm
Proof spirit, Degrees proof: 3.7.3
Prop-2-enal, C3H4O, acrolein
Prop-2-en-1-ol, CH2:CHCH2OH: Allyl alcohol
Propan-1, 2-diol, propylene glycol
Propanal, CH3CH2CHO, propionaldehyde
Propane gas, C3H8
Propane-1, 2, 3-triol, C3H8O3, Glycerol, glycerin, glycerine
Propanethial S-oxide, C3H6OS:
Propanedioic acid, C3H4O4, malonic acid
Propanoic acid, C2H5COOH, propionic acid
Propanol (C3H7OH): 16.1.3a
Propanone, CH3COCH3, acetone
Propellants, packaging gases, food additives: 19.4.22
Propene, propylene, methylethylene: Density (Table)
Propenoic acid, C3H4O2, acrylic acid
Propionaldehyde, CH3CH2CHO, propanal
Propionamide, CH3CH2CONH2, propanamide, propylamide
Propionic acid, C2H5COOH, propanoic acid
Propyl acetate, propyl ethanoate, n-propyl acetate, Toxic by all routes, Highly flammable
Propyl alcohol (CH3)2CHOH, isopropyl alcohol
Propyl bromide, 1-bromopropane: 12.18.13
Propyl butanoate, propyl butrate, moderately flammable
Propyl gallate, C10H12O5:
Propyl methanoate, n-propyl formate, Highly flammable
Propyl propanoate, propyl propionate, Highly flammable
Propylamine, C3H9N
Propylcyclopentane: See diagram 16.1.1h
Propylene dibromide, 1, 2-dibromopropane, Toxic by all routes, avoid inhalation
Propylene glycol, CH2OHCH2OH, antifreeze
Proscillaridin A, C30H42O8
Prostaglandins, based on fatty acids, in prostate glands, hormones, many functions
Protective clothing and equipment: 3.2.2
Protoalkaloids, Principle classes of alkaloids:
Protoanemonin lactone:
Protonated, organic chemistry term for when H+ ion is bonded to something
Protopine, C20H19NO5
Protostephanine, C21H27NO4
Protoveratrines, C41H36NO14
Prunasin, C14H17NO6
Prussian blue, C18Fe7N18, iron (III) ferrocyanide
Pseudoephedrine, C10H15NO, isomer of ephedrine
Pseudoephedrine, C10H15NO
Pseudohypericin, C30H16O9
Psoralen, C11H6O3
PS, Plastics recycling code: 3.5.3
Psicose, C6H12O6
Psilocybin, C12H17N2O4P
Psilocybin, C12H17N2O4P, Hallucinogenic drugs, hallucinogens: 11.9
PTC tasters and non-tasters: 9.24.2, phenylthiocarbamide
PTU, Prepare phenylthiourea solution: 1.13
PTFE, Polytetrafluoroetheylene: 3.7.32, "Teflon"
Publishers (Commercial websites)
Puerarin, C21H20O9, kudzu isoflavone, reduces alcohol withdrawal anxiety symptoms
Pulegone, C10H16O
Pumice: 35.21.4 (Geology)
Pumpkin seed oil, Dichromatism: 27.124
Pure substances and impure substances, elements and compounds: 7.2.0
Pure substances, Separate pure substances: 10.01.0
Purified, Chemicals standards
Purine, C5H4N4
Purine derivatives, True alkaloids: 16.3.22
Purines, DNA and RNA: 4.4.0
Putrescine, NH2(CH2)4NH2
Putty: 3.68
PVA, Polyvinyl alcohol:
PVC, polyvinyl chloride (C2H3Cl)n
Pyrazine (1, 4-diazine), N2C4H4, ligand
Pyrene, C16H10, Reactions of benzene, C6H6: 16.8.1
Pyrethrin, Plant extract insecticide, C21H28O3: 16.1.1
Pyrex, Borosilicate glass: 7.9.10
Pyridine, C5H5N:
Pyridine-3-carboxylic acid, C5H4NCOOH, nicotinic acid, niacin
Pyridine-piperidine alkaloid derivatives, True alkaloids: 16.3.19
Pyrimidine, Nucleosides, nucleic acids, DNA, RNA:
Pyrite, iron (II) sulfide, FeS2
Pyroelectricity, ferroelectricity: 35.33.1 (Geology)
Pyrogallol, C6H3(OH)3
Pyrolusite, manganese (IV) oxide, mineral, MnO2
Pyromorphite group, Pb5(PO4)3Cl: 35.20.33
Pyrophoric liquids: 4.9
Pyrophoric solids: 4.10
Pyroxylin, Collodion, cellulose nitrate: 3.5.10 (ether and alcohol)
Pyrrhotite. iron sulfide, FeS: 35.20.34
Pyrrole (CH)4NH, five member heterocycle
Pyridine-piperidine alkaloid derivatives: 16.3.19
Pyrrolidine, C4H9N, alkaloid
Pyrrolidine derivatives, True alkaloids: 16.3.20
Pyrroline, C4H7N, 1-Pyrroline
Pyrrolizidine, C7H13N
Pyrrolizidine derivatives, True alkaloids: 16.3.21
Pyruvic acid
Pyrylium ion: See diagram

Palladium, Pd
, Pd, Table of Elements
Palladium properties,
Palladium (II) acetate
Palladium (II) chloride
Palladium AAS Solution
Palladium hydroxide on carbon
Catalytic converter:

Palladium, Pd (Greek Pallas (Athene) goddess), white metal, hard, ductile, similar to silver, used in jewellery and as catalyst,
transition metal, free element, formerly called "new silver", and used for contact points for flintlock pistols, boiling vessels and crucibles.
Now used as foil, powder and wire, in low voltage electrical contacts, and as palladium catalysts for organic chemical synthesis and
carbon bond forming reactions, e.g. C-C, C-O, C-N and C-F.
Lustrous silver-white metal.
Resistant to corrosion in air and acids, but is attacked by hot acids, and dissolves in aqua regia.
It can absorb up to 900 times its own volume of hydrogen.
Used jewellery as "white gold" alloys with platinum.
It is now the main ingredient of catalytic converters reduce emissions from car exhausts, replacing platinum.
Also used in wide screen televisions, computers and mobile phones, as tiny multi-layer ceramic capacitors.
Atomic number 46, Atomic mass 106.42 g. mol-1, Density 11.9 at 20C.
Melting point 1560 C, 9 isotopes, Standard electrode potential + 0.85 V (Pd2+/ Pd ).

Palmitic acid
Palmitic acid, CH3(CH2)14COOH, saturated fatty acid, hexadecanoic acid, cetylic acid, saturated F A,
in Olive oil
in Coconut oil, palm oil, animals and plants
Palmitic alcohol, hexadecanoic, cetyl alcohol, 1-hexadecanol, CH3(CH2)15OH
Palmityl alcohol, CH3(CH2)14CH2OH, hexadecanol
Palmityl alcohol, Melting point of different substances:

Pancreatin (contains pancreatic enzymes, trypsin, amylase, and lipase), digestive aid from animal pancreas
Pancreatin is used to replace digestive enzymes when the body does not have enough of its own.
Digestion in the intestines, pancreatin suspension: 9.224.

Pantothenic acid, vitamin B5
Pantothenic acid, C9H17NO5, vitamin B5, the D-isomer is a water soluble essential nutrient in most food, especially egg yolks, sunflower seeds, blueberries, mulberries, cherry tomatoes.
Pantothenic acid, an antioxidant, is a component of coenzyme A (CoA) and a part of the vitamin B2 complex, a growth factor essential for many metabolic functions
and synthesis of cholesterol, steroid hormones, and other biochemicals
. Calcium pantothenate, C18H32CaN2O10, is used as a stable dietary supplement.
Freezing, thawing and cold storage of meat: 19.3.06
Nutritional value of eggs: 22.20
Thermal processing, cooking and canning of food: 19.3.07.

Paraffin oil, kerosene
Nitroparaffins, nitroalkanes:
Paraffin, alkanes (CnH2n+2):
Paraffin oil, kerosene, fractional distillation:
Paraffin wax, fractional distillation:
Kerosene, paraffin oil, distillation:
Kerosene for bath cleaning: 19.6.4
Kerosene, emulsions, detergent:
Catalytic cracking of kerosene: 10.6.4
Prepare household soap: 19.6.6.

Kerosene, Highly flammable, Toxic by all routes, avoid vapour inhalation, skin irritant
1. Use kerosene to clean chrome-plated taps, to soak greasy overalls before washing with soap powder.
Use kerosene-soaked cheesecloth left to dry for furniture dusters.
Paraffin, hard paraffin wax (chunks), alkane mixture, CnH2n+2, paraffin wax black 43 / 46
The term "paraffins" was the former name for "alkanes".
Paraffin (Latin: parum little, affinis connected), because of its low chemical activity.
The name invented by German chemist Karl Reichenbach in 1830. 1. Paraffin, fp 60oC (UK paraffin oil) (USA, Australia, kerosene),
(also kerosine, "kero"), is a petroleum fraction containing a mixture
of about ten different hydrocarbons, 10 to 16 carbon atoms per molecule, depending on the origin of the original petroleum.
Its flash point (temperature to form flammable vapour), is 38oC, so it is a relatively safe fuel.
Use paraffin oil, kerosene, in a well-ventilated space for kerosene lamps and domestic heaters, but do not use it as a degreaser of
2. Paraffin wax is alkanes C20H42 to C40H82, and is used to make candles, polish, "wax" paper.
3. Liquid paraffin (petrolatum liquid, paraffin liquid), is a pure mineral white oil emulsion used as a medicine
It is a colourless, tasteless, liquid form of petroleum jelly, mixture of >C12 alkanes, known as petrolatum jelly ("Vaseline", trade name)
White paraffin, is another kind of petroleum jelly.
Paraffin wax, has m.p. 45 to 65oC (pastillated wax, 52oC), relative density 0.9.

Paracetamol, Acetaminophen, C8H9O2, (Paracetamol, Tylenol): 11.11.6
Paracetamol glucuronide
Paracetamol, Separate, chromatography:

Pachypodol, C18H16O7, flavonol, in Korean mint.

Paraldehyde, C6H12O3, colourless liquid, hypnotic, sedative, anticonvulsant, but seldom used because
administration difficult, so now a former sedative.

Arachis hypogaea, groundnut, peanut, Fabaceae.
Arachidic acid (icosanoic acid), C19H39COOH, CH3(CH2)18COOH, (in peanut oil)
Arachis oil (peanut oil), fixed oil, non-volatile oil
Classification of fats:
Composition of edible oils: 19.2.11
Cooking fats: 19.1.17
Energy from peanuts:
Electrical conductivity of liquids: 3.60 (Peanut oil)
Food allergies and intolerances, "hyperactive": 19.2.0 (See: 5. Oil allergy)
Fatty acids in oils of natural products: 17.6
Lectins: 16.3.17
Lipids, fats and oils, fatty acids, glycerides:
Microbial contamination of food: 19.3.11
Peanut (Arachis hypogaea), Fabaceae.
Peanuts (groundnut) (Arachis hypogaea): 4.24 (care and harvest)
Pod: A dry fruit that opens on two sides to let the seeds out, e.g. legume (cowpea, wing bean, peanut)
Solvent extraction of oil from peanuts: 10.12.1.

E440 Pectins
Pectinase, Enzyme technology: 7.1.1
Prepare pectinase: 4.2.9
Tests for pectin in jelly and jam:

Pentan-1-ol, colourless liquid, bad smell
Pentan-1-ol, C5H12O, 1-pentanol, n-amyl alcohol, n-amyl alcohol, normal amyl alcohol, Toxic, Flammable
Pentan-1-ol, Solution < 25%, Not hazardous
Pentan-2-ol, C5H12O, 2-pentanol, sec-amyl alcohol, n-pentyl alcohol, Toxic by all routes, Flammable
Pentan-2-one, methyl propyl ketone, Toxic by all routes, Highly flammable
Pentan-3-one, diethyl ketone, Toxic by all routes, Highly flammable.

Pentane, n-pentane, C5H12, CH3(CH2)3CH3, colourless liquid,
Pentane, Highly flammable, so use other less volatile alkanes
Pentane (C5H12):
Pentane: See diagram 16.1.1h octane number
Pentane-1, 5 diol
Pentanedioic acid, glutaric acid (not glutamic acid!), COOH(CH2)3COOH
Pentanoic acid, valeric acid:

Pentyl alcohol, pentan-1-ol (amyl alcohol, n-pentyl alcohol, C5H11OH)
Pentyl butyrate, n-amyl butyrate (apricot odour), moderate flammability
Pentyl ethanoate, C5H12O, n-amyl acetate, normal amyl acetate, pentyl acetate, 1-pentanol
Pentyl propanoate, n-amyl propionate, Highly flammable
Prepare amyl acetate (pear oil): 16.5.6.

Pepper, black pepper, betel pepper
Pepper, black pepper, spice, Piper nigrum
Betel pepper, Piper betle, consumed as betel quid (pan), containing betel leaf, areca nut and slaked lime.
Betel leaf (Piper sarmentosum), Piperaceae.
Betel nut palm (Areca catechu), Arecaceae.
Betel pepper (Piper betle), Piperaceae
Chilli pepper, Capsicum annuum, Solanaceae
Chilli Project
Piperaceae (pepper family), Piper nigrum, pepper, black pepper, Piper methysticum, kava
Separate pepper from salt: 31.2.8
Sprinkle salt on water, surface contracts momentarily towards crystals, opposite with pepper
Succulent fruits (fleshy fruits): 9.5.3
Tomato family (Solanaceae): 6.6.9
Use pepper, black pepper, around skirting boards before carpeting to deter silverfish.

Peptides, polypeptides
Peptides, peptide bond
Models, Peptides, (Commercial)
Amino acids:
ATP, adenosine triphosphate:
Blood constituents (humans): 9.214
Fibrous proteins and globular proteins:
Glycoproteins: 16.3.16
LSD (lysergic acid diethylamide):
Molecular models: 3.5.1
Proteins, peptides, amino acids: 16.6.0
Structural forms of proteins:
Tests for proteins, biuret test: 16.6.5
Tests for proteins, heat test for proteins: 16.6.1.

Peptides have amino acids linked in a linear sequence, where the carboxyl group of a amino acid is linked to the amino group of the
next amino acid.
A covalent bond forms between the carbonyl carbon of a amino acid with the nitrogen atom of the next amino acid, with the loss of
Peptides include structures formed from α-amino acids and from any amino carboxylic acid.
Natural peptides include oxytocin (uterus contraction hormone and stimulates lactation), and insulin (pancreatic hormone).

Perchloric acid, HClO4
Perchloric acid, HClO4, chloric (VII) acid, 70% W/W (strong acid), clear, colourless, odourless aqueous solution, Toxic by all routes
Perchloric acid, strong oxidizing agent if hot, spontaneous explosion of soaked wood, explosive mixture with combustibles or organic
compounds, corrosive to metals and tissues, closed containers may rupture violently if heated
Perchloric acid should not be used or stored in a school science laboratory.
Storing oxidizing agents:

Periodic acid, H5IO6
Periodic acid, H5IO6, Toxic by all routes, explosive mixture with combustibles or organic compounds
ACS reagent, 100 g in glass bottle.

Periodic Table
See: Periodic Table (Commercial)
Introduction to the periodic table: 1.10.1
Oxides and the periodic table:
Patterns in the periodic table: 1.10.2
Periodic table: Table 1
Periods: 1.11.0
Reactions of calcium and calcium compounds: 12.4.1.

Permanganate ion
Permanganate, manganate (VII) ion, MnO4-
Permanganates have purple colour and are soluble in water, noncombustible, but accelerate burning of combustible material,
especially finely divided material when permanganates may spontaneously ignite.
Contact of permanganates with sulfuric acid may cause fire or explosion.

See: Petroleum Jelly (Commercial)
Petroleum, petrol, gasoline, "gas", Highly flammable, Toxic by all routes.
Do not inhale vapour.
Do not use petrol as a paint "thinner"
Cracking, thermal and catalytic cracking:
Fractional distillation of crude oil: 16.1.12
Petrol, "gas", gasoline, motor fuel:
Petroleum (crude oil and gas): 35.23.4, (Geology)
Petrol-sniffing (Abuse of volatile substances): 11.11.2
Petroleum-based spray oils, + emulsifying agent, horticultural oils, block insect spiracles, e.g. "PestOil"
Petroleum, Composition of gasoline: 10.6.3
Petroleum ether, Cleaning agents, solvents: 2.20.4
Petroleum fraction: 7.9.41
Petroleum spirit:
Petroleum jelly, "Vaseline", petrolatum.
"Vaseline" is a trade name for petroleum jelly.

Pewter, malleable, alloy of mostly Sn, + some Cu, Sb, and Bi,
previously used for cheap mugs and dishes.

pH tests
See: pH (Commercial)
Acid-base indicators
Acidity and alkalinity:
pH change near the equivalence point: 12.10.10
Multiple reagent strips:
pH of salt solutions: 12.10.4
pH of solid acids: 19.1.2
pH of swimming pools: 18.3.0
pH soil test: 6.50.1
pH tests (Environmental chemistry): 18.1.0
Prepare acid-base indicators: 37.0
Soil acidity, soil pH: 6.1.0
Soil pH tests, acid soils and alkaline soils: 6.12.0
Tests for pH of water (lakes and rivers): 18.1.0 (Environmental chemistry)6.12.1

1, 10-phenanthroline monohydrate, use in fume cupboard or < 10 g in cross ventilation (redox indicator), Toxic
1, 10-phenanthroline iron complex, ferroin solution (redox indicator), Toxic if ingested
1, 10-phenanthroline iron complex, [10-phenanthroline with iron (II) salt], purchase already diluted solution.

Phenyl group, C6H5
1-phenylazo-2-naphthol, sudan I, C.I. Solvent Yellow 14, Toxic. skin irritant, purchase solution
3-phenylpropenoate, C11H12O2 (Ethyl cinnamate, 3-phenylpropenoate, Toxic, Flammable)
3-phenyl propenoic acid, C9H10O2, C6H5CH:CHCOOH, cinnamic acid, Toxic if ingested
Phenyl benzoate, C13H10O2 (recrystallization experiments, ethanol solvent), benzene substitute, Toxic, Irritant, Flammable
Phenyl bromide, Bromobenzene: 12.18.3
Phenyl salicylate, C13H10O3
Phenylalanine, C9H11NO2
Phenylamine, C6H5NH2,
Phenylammonium chloride, C6H5NH2.HCl, aniline hydrochloride
Phenyldimethylamine, C8H11N, dimethylaniline
Phenylethene, C6H5CH:CH2, Styrenes: 3.8.2
Phenylethene, C6H5CH:CH2, vinyl benzene, styrene
Phenylethylamine, C6H5CH2CH2NH2
Phenylformic acid, C6H5COOH, benzoic acid, benzene carboxylic acid
Phenylhydrazine, C6H8N2, Highly toxic by all routes
Phenylhydrazine, C6H8N2, Solution / mixture < 1%, Not hazardous
Phenylhydrazine hydrochloride, phenylhydrazinium chloride, Highly toxic by all routes
Phenylhydrozone, C13H12N2, benzaldehyde
Phenylmethyl benzoate, C6H5COOCH2C6H5. benzyl benzoate
Phenylthiocarbamide, C7H8N2S, PTC, phenylthiourea, (PTU), tasters: 9.24.2
Phenylthiocarbamide, C7H8N2S, PTC: 1.13
Phenylthiourea, C7H8N2S, phenylthiocarbamide, 1-phenyl-2-thiourea (rat poison), Highly toxic if ingested, asthmatics may be allergic
Phenylthiourea, C7H8N2S, 0.1% solution soaked in paper used for taster / non-taster genetic test, Experiment Not permitted in schools
Phenylurea, C6H5NHCONH2, phenylcarbamate, Toxic if ingested.

Phenyl salicylate, C13H10O3
Phenyl salicylate, C13H10O3, phenyl-2-hydroxybenzoate, salol, Toxic if ingested, flammable
Prepared by heating salicylic acid with phenol
Used in experiments to show cooling rates affect crystal size, formerly in sunscreens

Phenylalanine, C9H11NO2
Phenylalanine derivatives, True alkaloids: 16.3.30
Phenylalanine, DNA codons
Phenylalanine, sweetener: 19.2.6
Phenylalanine (Table of amino acids).

See: Phosphates Elements, Compounds, (Commercial)
Phosphate ion: PO43-
Ammonium phosphate (NH4)3PO4, triammonium phosphate (V)-3-water, ammonium phosphate tribasic, nitrogen and phosphorus
garden fertilizer, flame retardant, added to baking powders to promote yeast growth
Ammonium sodium hydrogen phosphate (V)-4-water, Na(NH4)HPO4.4H2O, ammonium sodium hydrogen orthophosphate, microsmic
salt (from urine)
Ammonium sodium hydrogen orthophosphate, Na(NH4)HPO4.4H2O, microsmic salt (from urine)
ATP, adenosine triphosphate:
Bone phosphate: E542
Calcium phosphate
Chromium (III) phosphate, CrH8O8P, Chromium (III) phosphate tetrahydrate
Decomposition of phosphates: 3.30.13
Detergent phosphates: 12.12.05
Detergents use polyphosphates or zeolite to make calcium inactive in the system
Diammonium phosphate, diammonium hydrogen phosphate (DAP) (NH4)2HPO4
Food additives: 19.4.4 (Search: phosphate, e.g. Potassium phosphates: E340)
Group tests for phosphorus and phosphates: 12.13.0
Inorganic builders in washing powders:
Monoammonium phosphate (MAP)
Monopotassium phosphate (MKP)
Phosphate buffer reagent: 9.2.25
Phosphate ions in water: 18.4.1
Phosphates, essential for development of bones and teeth, genetic material
Phosphates hazards: 3.7.14
Phospholipids (phosphoglycerides):
Phosphorylation means adding a phosphate group to a molecule
Phosphorous compounds, organophosphorus insecticides: 16.2.6
Prepare solutions:
Reactions of phosphorus and phosphates: 12.13.1
Remove water hardness:
Soaps and synthetic detergents, "syndets": 12.12.0
Sodium acid pyrophosphate food grade
Sodium dihydrogen phosphate (V)
Sodium hexametaphosphate (SHMP)
Sodium tripolyphosphate (STPP), Na5P3O10
Soil-less culture, Knop's, hydroponics:
Struvite mineral, [(NH4)MgPO4.6H2O], ammonium magnesium phosphate
Superphosphate production: 12.14.5
Teeth and toothpaste, calcium hydroxyapatite: 9.226
Tests for phosphates:
Tetrapotassium pyrophosphate (TKPP )
Trisodium orthophosphate, Na3PO4 (TSP), "sodium phosphate", E339
Urea phosphate, UP, CH7N2O5P, urea phosphoric acid.

Phloroglucinol, C6H6O3, 1, 3, 5-trihydroxybenzene, benzene-1, 3, 5-triol, Harmful if ingested, corrosive to skin, 1% solution in ethanol, as wood stain
Microscopy stain: 3.22
Microscope staining techniques: 9.61 (See: 3. Test for lignin).

Phosphine, PH3
Phosphine, PH3, gas, colourless, flammable, high toxic, rotten fish garlic smell, silicon solid state device doping agent, grain insecticide,
"QuickPhos", in marsh lights (will-o'-the-wisp), from decayed organic matter
Diphosphane, P2H4.

Europium, Eu
Fluorophores: 14.3.0a
Phosphorescence: 7.33.3 (chemistry of phosphorus)
Phosphorus: (See: 2.)
Terbium, Tb.

Phosphoric acid
Phosphoric acid, concentrated, 16 M, 95%,
Phosphoric acid 85% min food grade 130 mL of concentrated solution for 1 litre of 2 M solution.
Phosphoric acid, > 4 M (72%) (may be supplied as 85%) (used in rust converters), Toxic. Highly corrosive to skin
Phosphoric acid, < 4 M (72%), > 2 M (36%), Toxic. Highly corrosive to skin
Phosphoric acid, < 2 M (36%), > 0.5 M (10%), Toxic. skin irritant
Phosphoric acid, < 0.5 M (10%), Not hazardous, but do not ingest.

Phosphoric acid, H3PO4, orthophosphoric acid, phosphoric (V) acid, crystalline, as solution is colourless, odourless liquid,
conc. 14.7.M, r.d. 1.71 to 1.75, miscible with water and ethanol, "Kill-rust", E33, weak acid, or, white rhombic solid,
85% W /W, 90% W / W, toilet bowl cleaner.
Phosphoric acid is prepared in industry by heating calcium phosphate rock with sulfuric acid, prepare by red phosphorus with nitric
Low cost: from hardware stores, rust remover, e.g. "Naval Jelly", "Kill rust", or, for cleaning concrete, from brewing or wine making
suppliers, from hydroponics suppliers.

See: Phosphorus Elements, Compounds, (Commercial)
Phosphorus, P, Table of Elements
Reactions of phosphorus, P: 12.13.0
Phosphorus compounds
Phosphorus deficiency: 1.11.0 (in soil)
Phosphorus deficiency symptoms: 1.5.4 (in plants)
DEA list of chemicals: 3.9.5 (See: phosphorus)
Reactions of phosphorus: 12.13.1
Red phosphorus: 7.33.1
Red phosphorus, safety matches: Matches
Superphosphate production: 12.14.5
White phosphorus: 7.33.2
Tests for phosphorus and phosphates: 12.13.0.

Phosphorus, P
(Greek phōsphoros, light-bringing), non-metal, allotropes, white waxy solid, in
minerals and organisms, occurs mainly as phosphates and in many minerals, e.g. apatite.
Phosphorus has 2 main allotropes:
1. White phosphorus, yellow phosphorus, translucent, white-yellow, very reactive, poisonous, not permitted in schools
2. Red phosphorus, high mp. low reactivity, low toxicity
Phosphorus-32, reactor-produced medical radioisotope, half-life 14.28 days, used to treat excess red blood cells.
Phosphates are important agricultural fertilizers, e.g. NPK.
See: Phosphate Elements, Compounds, (Commercial)
Phosphorus occurs as inorganic calcium phosphate in bones and teeth, in tissue and in the ATP molecule, and in urine.
The recommended daily allowance, RDA, is 1200 mg.
Phosphoric acid, H3PO4, behaves as a tribasic acid although the normal salts are much hydrolysed in solution.

Phosphorus compounds
Decomposition of phosphates: 3.30.13
Detergent phosphates: 12.12.05
Diphosphane, P2H4
Matches, safety matches
Organophosphates and carbamate insecticides: 16.2.2
Phosphine, PH3
Phosphorous compounds, insecticides: 16.2.6
Phosphorus deficiency: 1.11.0
Phosphorescence: 7.33.3
Phosphoric acid
Phosphoric acid, ionization reaction: 12.9.0
Phosphorus (III) chloride, PCl3, phosphorus trichloride, + water --> phosphorous acid, H3PO3
Phosphorus (V) chloride, PCl5
Phosphorus acid, H3PO3 (HO)2HPO, HPO(OH)2, garlic-like odour, very soluble in water
Phosphorus oxychloride, phosphoryl chloride, Highly toxic by all routes, Highly corrosive, toxic fumes and heat with moisture
Phosphorus oxychloride, Solution / mixture < 5%, Not hazardous
Phosphorus pentachloride with water:
Phosphorus pentoxide
Phosphorus pentasulfide
Phosphorus sesquisulfide, P4S3, yellow solid, in "strike anywhere" matches
Phosphorus tribromide, phosphorus (III) bromide, Highly toxic by all routes, Highly corrosive,
Phosphorus tribromide, reacts with moisture to form toxic fumes and heat, so use in fume cupboard or small quantities in
Phosphorus tribromide, Solution / mixture <5%, Not hazardous
Phosphorus trichloride with water: 12.13.4
Phosphonates, Ethephon, Glyphosate: 9.88.1
Prepare microcosmic salt: 12.13.5
Prepare phosphorus trichloride, PCl3: 12.13.2
Prepare phosphorus pentachloride, PCl5: 12.13.3
Prepare phosphorus pentoxide:
Reactions of phosphites, HPO32- : 12.13.6
Reactions of phosphorus, phosphates: 12.13.1.

Phosphorus pentoxide, P2O5, phosphoric anhydride, P4O10, phosphorus (V) oxide, phosphoric oxide, white powder, hexagonal
crystals, deliquescent, thermoluminescent, Toxic by ingestion, Highly corrosive
Prepare nitrogen gas: 3.46
It reacts violently with water to form phosphoric acid, liberating a large amount of heat, reacts violently with iodides.
With sodium and potassium metals ignition on contact.
With formic acid forms highly toxic carbon monoxide gas.
Used as a dehydrating agent.
The crust on the surface of old samples is mostly phosphoric acid, but remove it before using the phosphorus pentoxide beneath.

ATP, adenosine triphosphate:
Tests for glucose, urine test:
Tetrapyrroles, bilin, bilirubin, biliverdin, haeme:
Phosphorylation means adding a phosphate group to a molecule.

Phosphorus (V) chloride
Phosphorus (V) chloride, PCl5, phosphorus pentachloride, light yellow colour, + hot water --> ortho-phosphoric acid, H3PO4
Phosphorus (V) chloride, PCl5, phosphorus pentachloride
Phosphorus (V) chloride, phosphorus pentachloride, Highly toxic by all routes, highly corrosive
Phosphorus (V) chloride, Solution / mixture < 5%, Not hazardous:

Photochemical reactions
"Sun Blueprint Paper", photochemical reactions (toy product)
Chloramines in swimming pools: 18.7.23
Chlorofluorocarbons, CFCs, "Freons":
Ozone and photochemical smog: 3.50.01
Photolysis: 7.9.42.

Silver chloride precipitate in photography:
Photography, Reactions of silver halides:
Photography wastes, Disposal:

Photosynthesis: 6.5.0
Photosynthetic pigments, chlorophyll a and chlorophyll b:
Tests for photosynthesis: 6.5.7.

Picric acid
Picric acid (NO2)3C6H2OH, 2, 4, 6-trinitrophenol, trinitrophenol, carbazotic acid, Toxic. skin irritant, Not permitted in schools
Picric acid, yellow crystals stain skin yellow
Explosive when dry and compacted
Do not open bottles because crust may explode.
Picric acid, C6H2(NO2)3, 2, 4, 6-trinitrophenol, stains yellow, unstable explosive. used in Gram stain and Bouin's picro-formol
preservative solution.
Picrates, salts of picric acid (2, 4, 6-trinitrophenol).

See: Piezoelectric
Ammonium dihydrogen phosphate, monobasic ammonium phosphate (piezoelectric crystal in microphones and transducers)
Earphones, crystal microphones: 38.2.05
Potassium sodium tartrate-4-water
Piezoelectricity (voltage produced by mechanical stress to crystals):
Piezoelectricity with red lead and sulfur: 35.33.0
Transducer, carbon microphone: 26.9.01.

Pitch, resinous semi-liquid distillate from wood tar, for caulking wooden ships, link torches were used in dark streets.

Plaster of Paris
Plaster of Paris, calcium sulfate hemihydrate, hygroscopic, CaSO4.H2O, Harmful, very hot when water added to dry sulfate
Plaster of Paris, calcium sulfate, gypsum: 35.22.6
Heat calcium sulfate, gypsum: 8.3.5
Fibrous plaster board with plaster of Paris: 3.2.6
Make objects and moulds with plaster of Paris: 3.2.7
Tests for strength of plaster of Paris bricks: 3.67.0

See: Platinum Elements, Compounds, (Commercial)
Platinum, Pt, Table of Elements
Platinum properties:
Platinum, natural platinum: 35.20.31
Catalytic converter in a car:
Catalytic oxidation of ammonia forms nitrogen monoxide, with red-hot platinum wire:
Chloroplatinic acid
Platinum (IV) chloride, PtCl4
Platinum (IV) oxide, platinum dioxide, P2O2
Adams's catalyst, platinum oxide hydrate, PtO2.H2O, organic hydrogenation catalyst
Platinum, Pt (Spanish plata silver, platinum has silvery colour), platinum wire, 0.375 mm diameter, loop for inoculation of microbial
cultures, possibly sensitizes skin, powder
Platinum Group of Metals (PGMs), jewellery plating industry term for "4 PGM's, platinum, rhodium, osmium, ruthenium, iridium"
Chloroplatinic acid, hexachloroplatinic acid, H2PtCl6.(H2O)6 or [H3O]2[PtCl6].4H2O, platinic chloride PtCl4]
Platinic chloride, chloroplatinic acid
Platinum (IV) chloride
Platinum (IV) oxide.

Platinum is a soft, ductile transition metal, resists most chemical agents and does not oxidize at high temperature, available as foil and
wire, occurs in free elemental form placer deposits or in alloys, used for electrical contacts electrodes and jewellery.
No reaction with dilute HCl or H2SO4, air, water or concentrated oxidizing acids, e.g. HNO3 or H2SO4, reacts with aqua regia
(concentrated HNO3 + HCl) to form H2PtCl6.
Platinum is malleable, ductile and can be cut into slices.
It has a slightly grey lustre.
It is harder than gold and silver, so it is mixed with those metals when making rings and other jewellery.
Platinum vessels can hold acids because they do not react with them.
Platinum was first used for decorative objects and jewellery settings, but nowadays is used in scientific apparatus, electrical equipment,
electrodes and resistance thermometry and many industrial processes as a catalyst.
It has weak magnetism.
Platinum black is used as a catalyst in chemical reactions.
Platinum can absorb hydrogen and is used in catalytic converters to treat exhaust gases of motor vehicles.
The melting point of platinum is 1768oC, higher than gold, bronze and iron.
It was used to cast the platinum-iridium cylinder called the International Prototype Kilogram (IPK), in France because of its high
density and resistance to corrosion.
A "platinum" record has sold one million copies.
Atomic number: 78, Relative atomic mass: 195.08, r.d. 21.4, m.p. = 1769oC, b.p. = 4530oC.
Specific heat capacity: 134 J kg-1 K-1.

Plutonium, Pu,
, Pu (Greek Ploutōn underworld god), alloyed with Gallium in nuclear weapons core, "the most complex element in the
periodic table", isolated from uranium by Glen Seaborg in Chicago, 1942 within the Manhattan Project later used in the first atomic bomb.

See: Polonium Elements, Compounds, (Commercial)
Polonium, Po
(Latin Polonia Poland, native country of Marie Curie), radioactive poison to treat lung cancer.

Polymers and plastics: 3.0
Polymers and plastics (Experiments): 3.4.0
Poly-, polymers and plastics, Plastics called "Poly-"
Polycaprolactam Perlon plastic, Fibre from polycaprolactam:
Polychlorinated biphenyls, PCBs : 3.7.13.
Polyethylene glycol, poly(ethylene glycol), PEG, H(OCH2CH2)nOH, C2nH4n+2On+1,
Polyethylene oxide, poly(ethylene oxide), PEO (-CH2CH2O)n
Polyethylene terephthalate, Birefringent clear plastics, PET : 27.189
Polyketide, organic compound, carbonyl groups alternate with single carbon atoms in a chain, -CO-C-CO-C-
Polyketides, polyketide antibiotics:
Polymethyl methacrylate, PMMA, Acrylic resin, Perspex (Lucite): 3.7.24
Polypeptides, peptides
Polyphenols: 16.1.6
Polypropenonitrile: 3.7.28
Polyprotic acids:
Polysaccharide gums:
Polyterpenes (many isoprene units):
Polytrifluorochloroetheylene, PTFE, : 3.7.32
Polyvinyl acetate, polyvinylacetate, PVA: 3.7.36
Polyvinyl alcohol, PVA, PVOH:
Polyvinyl chloride, PVC, polychloroethene: 3.7.37
Polyvinyl chloride: PVC
Polyvinyl pyrrolidene:

3.7.24 Polymethyl methacrylate
Attraction and repulsion, parallel currents: 30.3.11
Breakdown polymers into small molecules:
Breakdown of polymers with heat: 3.97
Cut window glass and Perspex (Lucite): 2.15
Density (characteristics of synthetic fibres): 3.6.1
Metal on Perspex, Volta's experiment: 31.1.19
van de Graaff generator: 31.9.0
Polymethyl methacrylate, poly(methyl methacrylate), [CH2C(CH3)CO2CH3)]n
Methyl methacrylate, CH2C(CH3)COOH3. methyl ester of methylacrylic acid, CH2=C(CH3)COOH
Lucite (C5O2H8)n (Perspex), Poly (methyl methacrylate), PMMA, acrylic glass, e.g. Plexiglass
Polymethyl methacrylate, PMMA, acrylic glass, e.g. Plexiglass, Perspex, (Lucite):
Polymethyl methacrylate, perspex, PMMA, acrylic resin, polymethymethacrylate, polymethyl 2-methylpropenoate, methyl
methacrylate, thermoplastic transparent polymer (Trade names, "Perspex", "Lucite", "Plexiglass").
See diagram 3.4.2: Methyl methacrylate, polymethyl methacrylate
Polymethyl methacrylate is a rigid, transparent material that transmits light better than glass.
PMMA is used for acrylic "glass" glazing, optical devices, perspex chips, perspex stirring rod, plexiglass, reflectors, domes, safety glass,
aircraft windows, baby baths, traffic signs.
Perspex is made by the polymerization of the monomer methyl methacrylate with lauroyl peroxide as a catalyst.
This reaction is highly exothermic if the concentration of the organic peroxide < 1% by weight.
Has very high molecular mass when in sheet form.

Precipitation, precipitates
Moisture leaves the air, precipitation: 37.8.0, (Weather)
Precipitation, decanting, filtration: 10.11.01
Precipitation, Coloured precipitates: 12.2.1c
Precipitation reactions, prepare salts: M3
Precipitation reactions (double decomposition, double exchange, metathesis)
Tests for precipitates when solutions added to lead (II) nitrate: 3.71.4
Tests for precipitates, salt solutions with other salt solutions: 3.71.3.

Praseodymium, Pr
, Pr (Greek prasios green, didumos twin didymium mineral), green compounds, ceramics, glass.

Precipitates, substances deposited as a solid from a solution
Coloured precipitates, double decomposition reactions: 12.2.1c
Precipitates with ammonium carbonate: 12.12.4
Precipitates with sodium bicarbonate: 12.1.19
Precipitates with sodium carbonate: 12.1.26
Precipitation reactions, neutralization reactions:
Precipitation, Moisture leaves the air: 37.8.0, (Weather)
Tests for precipitates, lead (II) nitrate: 3.71.4
Tests for precipitates, mix salt solutions: 3.71.3.

Proactinium, Pa (proactinium "parent of actinium" because radioactive decay to Actinium), radioactive, toxic,
no uses, most stable isotope Protactinium-231.

See diagram: 14.05
Promethazine, C17H20N2S, phenothiazine derivative drug, sedative, antiallergic, and used for motion sickness.

, Pm (Greek Prometheus, who stole fire from the gods), synthesized in radiation laboratory.

Propane gas, C3H8
Propane gas, a bottled gas, a liquefied petroleum gas (LPG)
propyl C3H7-, Stem name: prop-
Propane: See diagram: 16.1.1h, octane number
Density, propane (Table)
Packaging gases, propellants, food additives: 19.4.22
propane-1, 2, 3-triol, glycerin, glycerine
Relative molecular mass of gases, propane: 13.1.02.

Propionaldehyde, CH3CH2CHO, propanal, propyl aldehyde, Toxic by all routes, Highly flammable, suffocating odour
Propionaldehyde, Solution <20%, Not hazardous, but should not be ingested.

Propionic acid, CH3CH2COOH, propanoic acid, Corrosive by all routes, Highly irritant vapour, skin irritant
Propionic acid, Solution / mixture <10%, Not hazardous (stored grains preservative)
Propanoic acid, ionization reaction:
Propionates, Food preservation19.3.6.10.

Protease (peptidase, proteinase) is a proteolysis enzyme, it hydrolyses (breaks down) proteins into amino acids.
An endopeptidase is an enzyme which breaks peptide bonds other than terminal peptide bonds in a peptide chain,
and include ficin from fig tree latex, papain derived from papaya latex, bromelain (bromelase), extracted from pineapple stem
Food additive E1101 Proteases: papain, bromelain, ficin, enzymes (stabilizer, flour treatment agent, tenderizer, flavour enhancer),
avoid skin contact.
Proteases are used in bread making as a bread improver/flour treatment agent and raising agent.
Proteases acts on the yeast and gluten to improve the extensibility of the dough and strengthen the structure of the bread to retain the
carbon dioxide produced that causes the bread to rise.

See: Protein (Commercial)
Peptone: water-soluble mixture of polypeptides and amino acids from partial hydrolysis of protein, e.g. beef peptone.
Proteins, peptides, amino acids: 16.6.0
Breakdown of protein by micro-organisms: 4.3.7
Burn carbohydrates, fats and proteins: 16.9.1
Casein, fibrous and globular proteins:
Casein, thermoset plastics: 3.5.6
Milk proteins: 16.3.0
Protease: 7.1.4
Proteins, Multiple reagent strips
Tests for proteins, Albustix test strips: 16.6.8
Tests for proteins, Millon's test: 16.6.7

See diagram 16.21.10: Purine
Purine, C5H4N4, is a heterocyclic aromatic organic compound, a pyrimidine ring fused to an imidazole ring.
Two of the bases in nucleic acids, adenine and guanine, are purines.

Pyrogallol, C6H3(OH)3, benzene-1, 2, 3-triol, 1, 2, 3-trihydroxybenzene, pyrogallic acid, Highly toxic if ingested, corrosive to skin
Germination and air: 9.118
Test gas collected in a respirometer: 6.6.12
Toxicity, Poisons and First Aid: 3.10.0.

Pyrrolines, C4H7N, Cyclic Amines.
Pyrrolines, C4H7N, dihydropyrroles, isomers differ in position of double bond
1-Pyrroline (3, 4-dihydro-2H-pyrrole), cyclic imine, colourless, less dense than water, soluble in water and alcohol, strong ammonia smell
like shrimp seafood
2-Pyrroline, cyclic amine,
3-Pyrroline, cyclic amine.

7.33.1 Red phosphorus
(Greek phosphoros Morning star) (Discovered by Henning Brand, Germany, 1669), light from phosphorus caused by combustion of
oxides on its surface when exposed to air.
Red phosphorus, brown phosphorus, P4, is not poisonous, ignites above 300oC, has phosphorus atoms bound in a covalent network
so is less reactive than white phosphorus and can be stored in air, used in "safety match" striking surfaces that contain red phosphorus,
powdered glass, carbon black, a binder and a neutralizer, e.g. calcium carbonate.
Used for "doping" semiconductors.
Red phosphorus is relatively harmless compared with the white phosphorus allotrope.
However, some school systems do not allow red phosphorus to be used in school science experiments.
It is not poisonous when pure.
It is deliquescent so keep it in a sealed container.
Do not heat red phosphorus in a test-tube because it produces phosphorus vapour that condenses to form white phosphorus.
Red phosphorus forms violently explosive mixtures with oxidizing agents, e.g. metal nitrates (potassium nitrate, sodium nitrate,
potassium permanganate), nitric acid, chlorates, perchlorates, peroxides, peroxy salts.
Do not heat phosphorus on a platinum wire because it corrodes the platinum.
P (red) Atomic number: 15, Relative atomic mass: 30.9738, r.d. 2.34, m.p. = 590oC, b.p. = 280oC.
Specific heat capacity: 670 J kg-1 K-1

7.33.2 White phosphorus
White phosphorus (yellow phosphorus), P4, is too reactive to be used in school science teaching so it is not permitted in schools.
In 1943 tonnes of white phosphorus in incendiary bombs were dropped by Allies' air forces on Hamburg.
White phosphorus is waxy, poisonous, spontaneously flammable, reacts with oxygen gas in the air to form P2O5, so it is stored under
White phosphorus is extremely toxic.
On contact with iodine it ignites, with bromine it explodes, and it can be ignited with a hot glass rod.
Cover spilt white phosphorus with 0.2 M copper sulfate solution that converts it to harmless copper sulfide.
P (white) Atomic number: 15, Relative atomic mass: 30.9738, r.d. 1.82, m.p. = 44.2oC, b.p. = 44oC.
Specific heat capacity: 757 J kg-1 K-1.

7.33.3 Phosphorescence
"Glow in Dark Sheet and Pen", UV light pen on GID phosphorescent sheet, (toy product)
"Glow Jumping Putty", phosphorescence (toy product)
Phosphorescence is the green glow from the slow oxidation of white phosphorus, an example of chemiluminescence.
However, the term phosphorescence is also used to describe a situation when the luminescence persists although the exciting cause
has been removed.
A phosphorescent material irradiated with UV light will emit light of a lower energy for an appreciable interval of time.
If a phosphorescent powder is irradiated with another fluorescent material, when the radiation source is removed the phosphorescent
powder emits light for tens of seconds.
Marine phosphorescence is not caused by phosphorus, but by chemical reactions in bioluminescent bacteria.
However, rotting herring glows, caused by combustion of rotting products, Diphosphane, P2H4
Phosphorescent minerals continue to emit light after the ultraviolet light ceases.
Europium, Eu
Yttrium, Y
Terbium, Tb

Pyrolysis is decomposition caused by heat.
It usually involves a chemical change caused by the application of heat.
Charcoal production is made possible by cutting naturally growing trees and undergoing a process called pyrolysis which involves
heating wood in absence of oxygen.
A mixture of liquid, gas and charcoal is produced.
The process takes about 7 to 12 days in traditional kilns, where 8 to 12 kgs of wood are used to produce 1 kg of charcoal.
With the above inefficiency in the production and the growing usage of charcoal suggests that greenhouse gas emissions associated with
charcoal could reach 15 billion tonnes of carbon dioxide by 2050, which will be released into the atmosphere leading to climate change.