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Chemistry N
Table of Contents
N-Methylcytisine, C12H16N2O
N-Methylephedrine, C11H17NO
N-phenylethanamide, acetanilide, n-phenylacetanilide
N-propyl alcohol, p-propyl alcohol, propyl alcohol, isopropyl alcohol, iso-propanol, n-propanol
N-propyl carbinol
Nacre, mother of pearl: 35.20.54
Nail polish:
Naled, C4H7Br2Cl2O4: 16.4.4 (insecticide)
Names of chemicals, Correct names of chemicals: 3.4.1
Napelline, C22H33NO3
Naphthalene, C10H8
Naphthol, C10H8O
Naphthyl-, C10H7-
Narceine, C23H27NO8
Narcissin, C28H32O16, flavonol
Naringin, C27H32O14, flavonoid glycoside
Natamycin, C33H47NO13: E235
Natron, sodium carbonate decahydrate
Natural emulsifier, egg yolk:
Natural fibres, Burning tests for natural fabrics: 4.2.0
Natural gas: Methane
Natural rubber, latex: 23.6.1
Natural steroids, Steroids, sterols:
Neatsfoot oil
Neem oil
Nelson cell, Electrolysis of concentrated sodium chloride solution: 15.5.13
Neoandrographolide, C26H40O8
Neodymium, Nd
Neomycin, antibiotic, from Streptomyces fradiae
Neodymium Nd (magnets)
Neon, Ne
Neonicotinoid insecticides
Neoprene plastic, Polychloroprene: 3.7.12
Neoxanthin, C40H56O4
Nephrite jade, Hornblende: 35.17.0 (Geology)
Neptunium, Np
Neral, Citral B, C10H16O
Nerol, C10H18O
Neroli oil, Sour orange.
Nerolic acid, C10H16O2
Nessler's reagent
Netilmicin, C21H41N5O7
Network solids: 3.01.4
Neutral oxides, oxides: 12.17.0 (See: 4.)
Neutral red: 24 (indicator)
Neutralization reactions
New equipment, Unpack, check and sort new equipment: 2.8
Newton, Non-Newtonian fluids: 13.6.0
Newton, Sir Isaac Newton, 1642-1726, England
See: Newton (Commercial)
NF (National Formulary), chemicals standard
Niacin, Nicotinic acid
Nichrome alloy, nichrome wire
Nickel, Ni
Nicotine, C10H14N2
Nicotinic acid, C6H5NO2
Nightshade glycosides
Ninhydrin, Tests for ammonia or amino acids or proteins with ninhydrin:
Niobium, Nb
Nipagin, C8H8O3
Nitinol memory wire: 5.5.15
Nitramine, C7H5N5O8: 25 (indicator)
Nitrates, nitrites
Nitre (US: niter), Potassium nitrate, KNO3
Nitric acid, HNO3
Nitric oxide, NO
Nitrile, nitrile rubber
Nitrite ion: NO2-
Nitro, -NO2
Nitrobenzene, C6H5NO2
Nitrogen, N
Nitroglycerine (UK), Nitroglycerin (US), C3H5(ONO2)3:
Nitrosyl (NO+), cationic ligand
Nitrilotriacetic acid (NTA), C6H9NO6, tetradentate ligand
Nitrous acid, HNO2
Nitrous oxide, N2O
Nobelium, No
Noble gases: 1.9.0
Noble metals
Noble metals, Alloys of noble metals and coinage metals: 5.5.11
Nomilin, C28H34O9
Non-chlorine shock: 18.7.49 (swimming pools)
Non-Newtonian fluids: 13.6.0
Non-polar covalent bonds, Covalent bonds: 3.01.2 (See: 2.)
Nonanal, C9H18O:
Nonenal, C9H16O:
Noradrenaline, C8H11NO3, norepinephrine
Norathyriol, C13H8O6, tetrohydroxyxanthone
Nordihydroguaiaretic acid, C18H22O4
Norepinephrine, C8H11NO3
Norharmane, C11H8N2
Normal saline, physiological saline: 5.1.10
Normal solution, normality: 5.1.9
Noscapine, C22H23NO7
9.6.0 Nose and smelling, taste, flavour, odour
Not permitted in schools, chemicals: 15.10.0
Note, in perfumery, one of the important components characteristic of that brand
Note, in music, a single tone of a certain pitch from a musical instrument or a singer
Nothoapiole, C13H16O5:
NOx, Acid rain and nitrogen oxides: 3.48
NPK grade formula: 6.20.01 (Agriculture)
NSAID, nonsteroidal anti-inflammatory drug, e.g. aspirin
Nuclear fast red solution, Prepare: 3.31
See: Nuclear Physics (Commercial)
Nucleation: 24.1.01
Nucleic acid nitrogenous bases: 3.0.0
Nucleic acids, nucleosides, DNA, RNA:
Nucleic acids, DNA and RNA: 4.4.0
Nucleophiles, Electrophiles and nucleophiles, hydrogen chloride: 14.0
Nucleophilic reactions, Reactions of 2-bromopropane with hydroxide ions:
Nucleotide: (See: 6.)
Nutrient solutions, nutrients, nutrition

Napalm is petrol gelled with the aluminium salts of naphthalene acids and palmitic acids, used in flame throwers and napalm bombs.

Naphtha, formerly naturally occurring liquid petroleum.
Nowadays, mixtures of volatile flammable distillation products from petroleum, b.p. below 200oC, or from coal tar, these compounds
that are used as solvents.
Naphtha (mixture of C4 to C10 alkanes, cycloalkanes and aromatic hydrocarbons), photographic film cleaner, paint thinner, Highly
toxic by all routes, Highly flammable
Naphtha, ligroin, fractional distillation:
Naphthacene, anthracene, C18H12
Naphthalene red, Magdala red:
Naphthol, C10H8O, 1-naphthol, C10H7OH, α-naphthol, 1-hydroxynaphthalene, naphthalene-1-ol,
Toxic if ingested, may be carcinogenic

Naphthalene, C10H8
1, 4-dichlorobenzene, (substitute for naphthalene mothballs)
Burn mothballs: 12.8.2
Camphor, C10H16O: (substitute for naphthalene mothballs)
Dancing naphthalene mothballs:
Evaporate naphthalene mothballs: 12.8.1
Melting points of naphthalene: 3.2
Naphthalene acetic acid, C12H10O2, (NAA): (Plant growth regulator)
Naphthalene aromatics:
Naphthalene black, 4-methyl cinnamic acid, Stain and dyestuff, Toxic if ingested
Naphthalene, thermal decomposition: 3.30.12
Prepare naphthalene crystals from mothballs: 12.8.3
Reactions of chlorine, with benzene: 13.4.6
Reactions of dilute acids with NaHCO3: 12.3.10
Sublimation, thermal decomposition: 3.30.12.

Naphthalene, mothballs, C10H8, a fused pair of benzene rings, m.p. 80.26oC, flakes, crystals, marbles, balls, moth balls, flammable
solid, highly toxic by all routes.
Naphthalene is a white, volatile, solid polycyclic hydrocarbon with a strong mothball odor.
Naphthalene from coal tar or petroleum distillation, used to make phthalic anhydride, C6H4(CO)2O, plastics industry, moth repellents.
Naphthalene is in black walnut, many essential oils and Muscodor species fungi.
Exposure to naphthalene is associated with hemolytic anemia.
Naphthalene sublimes at room temperatures (approaching 70oC), toxic to humans in large doses, high flammability, white substance,
with a greasy feel and a peculiar penetrating smell, insoluble in water but dissolves in methylated spirit, forms as a by-product in the
manufacture of coal gas.
Uses include making dyes, protecting clothes and carpets from moths and controlling insect pests in soil.
It is possibly carcinogenic, so other chemicals should be substituted to deter moths and silverfish in the home, e.g. 1, 4-dichlorobenzene,
(paradichlorobenzene) and camphor.
MSDS Naphthalene:
Hazards Identification
Potential Acute Health Effects:
Very hazardous in case of ingestion.
Hazardous in case of eye contact (irritant), of inhalation.
Slightly hazardous in case of skin contact (irritant, permeator).
Severe over-exposure can result in death.
The substance is toxic to blood, kidneys, the nervous system, the reproductive system, liver, mucous membranes, gastrointestinal tract,
upper respiratory tract, central nervous system (CNS).
Repeated or prolonged exposure to the substance can produce target organs damage.
Repeated exposure to an highly toxic material may produce general deterioration of health by an accumulation in one or many human organs.

Naphthol, C10H8O, 1-naphthol, C10H7OH, α-naphthol, 1-hydroxynaphthalene, naphthalene-1-ol,
Naphthol, C10H7OH, 2-naphthol, b-naphthol, β-naphthol, naphthalen-2-ol, white solid, antioxidant in rubber products, antiseptic, tests
for primary amines

Naphthylamine, 1-naphthylamine, C10H7NH2, α-naphthylamine, Extremely toxic, possible carcinogen, Not permitted in schools
Naphthylamine, naphthalene-1-amine, unpleasant .
Natron, sodium carbonate decahydrate, Na2CO3.10H2O, + some NaHCO3, + NaCl, saline lake beds, used in Egyptian mummies.

Neatsfoot oil
Neatsfoot oil, from boiled cattle hooves, leather conditioner for saddles, boots, baseball gloves ("neat " is old word for "cattle").

Neodymium, Nd
NdS, Table of the elements
"Neodymium Disc Magnets", Nd
"Super Magnets", NdFeB
Neodymium, Nd (Greek didumos twin, mineral didymium), rare earth, pink compounds in ceramics
and tinted glass, in green laser pointers, wind turbines, electric cars, with Fe and B in very strong magnets
Karl Auer von Welsbach, 1858-1929, Austria, made the original discovery of neodymium in 1880 by separating the
supposed element "didymium" into praseodymium and neodymium.
Be aware that Neodymium magnets are brittle and break very easily.
Some teachers have a collection of broken and chipped magnets from student experiments.

Neon, Ne
See: Neon Elements, Compounds, (Commercial)
Neon, Table of Elements
Neon, properties
Atomic energy level, neon atom: See Fig. 11
Discharge of capacitor using a neon tube: 38.1.10
Density, Neon (Table)
Electrophorus: 31.6.0
Fluorescent lamp: 38.8.3
Incandescent lamp: 4.65
Neon relaxation oscillator, blinking neon bulb:
Spectroscope for materials analysis: 27.194
SVP, Saturation Vapour Pressure: SVP.

Neon, properties
Neon, Ne (Greek neon new), is a non-metal inert noble gas at room temperature and pressure, 0.0018% of the air, trace element in
atmosphere, low pressure discharge tubes in electric lights, high voltage display lighting, as bright orange colour, strip lighting in "Neon"
signs (Georges Claude, 1870-1960, France), very low reactivity, pilot electrodes (starter electrodes to start sodium vapour discharge
lamps), cold cathode tubes, manufactured by recovery from atmosphere.
George Claude, France, experimented with electrical charges within sealed tubes of neon to create in 1902 the first bright red neon light,
later to be adapted for advertising.
Atomic number: 10, Relative atomic mass: 20.179, r.d. 1.20 (27 K), m.p. = -249oC, b.p. = -246oC.
Specific heat capacity: 1.03 × 103 J kg-1 K-1.

Neptunium, Np
, Np (Latin Neptunus god of the sea), like Tantalum, in tantalite mineral, radioactive lanthanide.

Nessler's reagent
Tests for ammonia: 3.33.1
Nesslers reagent, K2HgI4, for qualitative determination of ammonia and ammonium compounds, potassium
tetraiodomercurate-potassium hydroxide, solution
Nessler's reagent is NOT permitted in some school systems because it contains mercury.
Nessler's solution (Julius Nessler 1827-1905), is a solution of mercury (II) iodide in potassium iodide made alkaline, with sodium
hydroxide or potassium hydroxide.
It may be in a caustic soda solution.
Add reagent to the original solution.
A brown colour or precipitate indicates the presence of ammonium ion.
The test is very sensitive.
A trace of ammonia give a yellow colour but larger amounts of ammonia give a brown colour or precipitate.
The test solution must contain no NH4+ added during analysis.

Neutralization reactions
Acid-base neutralization: 12.8.0
Neutralization reactions, Double replacement:
Heat of neutralization reactions: 3.82
Neutralization of soluble acid and base, prepare salts: M1.

Nichrome alloy, Nichrome wire
Wire, nichrome, bare, 16 swg, reel 125g
Nichrome alloy
Nichrome wire, 32 SWG, bare, 0.274 mm diameter, resistance 18.4 ohm / m (80% Ni, 20% Cr alloy), electric jug element
Conductivity, σ = 0.10 × 107 ohm metre
Resistivity, ρ = 100 -150 × 10-8 ohm metre
Temperature coefficient per oC = 0.0004
Energy from peanuts:
Expanding wire, sagging wire: 23.3.13
Galvanic cell, Voltaic cell, salt bridge: 33.84.2
Power surge circuit breaker, fuses:
Prepare silicon glass: 7.2.4
Resistance: 32.3.02
Resistance wire glass jar cutter: 2.21
Study the Bunsen burner flame: 3.1.3
Tests for oxygen gas: 3.49.1

Nickel, Ni
See: Nickel Elements, Compounds, (Commercial)
Nickel Table of Elements
Nickel properties:
Nickel compounds
Nickel: 35.20.29
Nickel-cadmium battery: 15.6.14
Nickel-metal hydride battery:
Nickel deficiency in soil: 1.9.0
Nickel deficiency symptoms: 1.9.4, (Soil)
Nickel powder
Nickel toxicity: 3.6.11
Niccolite, nickoline, arsenical nickel, NiAs.
Nichrome alloy, nichrome wire

Nickel plating, electroplating: 15.1.4
Reactions of nickel compounds: 12.9.4
Tests for nickel, dimethylglyoxime:

Nickel, Ni (German Kupfernickel, kupfer copper, nickel naughty goblin who causes no copper in mineral)
Nickel powder is toxic by inhalation, especially for pregnant women, keep wet to avoid ignition,
Ni-Al alloy,
Nickel-iron cell, Edison cell, NIFE cell, secondary cell.
Nickel as foil, powder, is a transition metal that resists corrosion.
It is obtained from ores containing NiS and is available as sheet.
It is used in shiny coin alloys, nickel plating, and in "silver" cutlery stamped "EPNS" (electroplated nickel silver), that has a shiny metal
protective coating.
It reacts with dilute HCl or H2SO4 to form H2 and metal ion and reacts with concentrated oxidizing acids, HNO3 or H2SO4 to produce
high oxidation number ions, and sulfur dioxide SO2 or nitrogen dioxide, NO2.
It reacts with steam to give the oxide and hydrogen gas.
Heated powder forms oxide.
The "nickel" coin in the U.S. is made of a nickel-copper alloy.
Atomic number: 28, Relative atomic mass: 58.69, r.d. 8.90 g cm-3| m.p. = 1453oC, b.p. = 2730oC.
Specific heat capacity: 439 J kg-1 K-1.

Nickel compounds
Nickel compounds, most nickel salts are sensitizers
Copper-nickel alloys: 5.5.9
Reactions of nickel compounds: 12.9.4
Millerite, NiS: 35.20.27
Nickel (II) acetate tetrahydrate
Nickel (II) bromide
Nickel (II) carbonate, basic hydrate, nickel carbonate pigment, Toxic if ingested
allergic reaction, use only < 2g of wet solid
Nickel (II) carbonate, Low cost: from pottery supplies stores.

Nickel (II) chloride, NiCl2
Nickel (II) chloride, nickel chloride pigment, Toxic if ingested, carcinogenic, allergic reaction, use only < 2 mL of 0.1 M solution
Nickel (II) chloride-6-water, NiCl2.6H2O, nickel (II) chloride hydrated, green crystals, nickel chloride, nickel chloride AAS Solution
Nickel (II) chloride, nickel chloride, For 0.1 M solution, 24 g in 1 L water.

Nickel (II) nitrate, Ni(NO3)2
Nickel (II) nitrate, nickel (II) nitrate hexahydrate, nickel nitrate, Toxic if ingested, allergic reaction, use < 2 mL of 0.1M per activity,
explosive with organics
Nickel (II) oxide, nickel oxide pigment, green glaze for craft, Highly toxic if ingested, carcinogenic to lungs.

Nickel (II) sulfate, NiSO4
Nickel (II) sulfate, NiSO4.6H2O, nickel (II) sulfate heptahydrate, Toxic if ingested, allergic
Nickel (II) sulfate, nickel sulfate, green crystals, blue salts
Nickel (III) oxide, black glaze, for craft
Nickel-cadmium battery, NiCad battery: 15.6.14
Nickel-metal hydride battery, NiMH: 15.6.14
Nickel-cadmium hydride, battery
Nickel boride
Nickel nitrate AAS Solution
Niccolite, nickoline, Arsenical nickel: 35.20.30.

Nicotine, C10H14N2, Isoquinoline Alkaloid
(alpha-nicotine. Pyridine derivative, Nicotinic acid --> nicotine)
Neonicotinoid insecticides: 16.1.0
Nicotine spray: 16.9.3
Nicotine, tobacco smoking & chewing: 11.11.16
Tests for cigarette smoke: 16.7.28.

Parasympathomimetic drug that stimulates the parasympathetic nervous system.
Colourless, poisonous and addictive, stimulant, nicotinic agonist, addictive because increases flow of
neurotransmitter dopamine in the brain, mimics the affects of acetylcholine, cheap insecticide using cigarette butts,
electronic cigarettes may cause nicotine overdoses.
Tobacco plant (Nicotiana tabacum), Solanaceae, nicotine in tobacco leaves
Smoking tobacco is associated with lung cancer and heart disease.
Neonicotinoid insecticides are related to nicotine.
Recent bans on neonicotinoid pesticides in Europe attest to the growing concerns surrounding pesticide use and honeybee decline.
Nicotine hemisulfate salt, Nicotine hydrogen tartrate salt
In Nicotiana tabacum, Asclepias syriaca, Lycopodium species, Sedum acre

Nicotinic acid
E375 Niacin
Nicotinic acid, C5H4NCOOH, pyridine-3-carboxylic acid, niacin, in vitamin B
complex (vitamin B3) (absence causes disease pellagra)
Nicotinic acid, niacin, E375: See diagram
Vitamin B1, nicotinic acid:
Nicotinic acid, niacin, Freezing: 19.3.02
Nicotinic acid in Celosia cristata, cockscomb, Amaranthaceae.

Niobium Table of Elements
Niobium, Nb (Greek Niobē daughter of god Tantalus, Niobum, Nb, is
associated with Tantalum, Ta).

Nitrates, Nitrites
See: Nitrates, Nitrites Elements, Compounds, (Commercial)
Nitrate ion: NO3-
Nitrate (nitroso), O-NO2-, monodentate ligand
Nitrite (nitrito), O-N-O-, monodentate ligand
Nitrite (nitro), N-O2-, monodentate ligand
Nitrate nitrogen soil test: 6.50.6
Nitration (of arenes):
Nitrites (NO2-:
Nitrites, Reactions of nitrites: 12.11.1
Brown ring test for nitrates:
Decomposition of nitrates: 3.30.4
Hazards: 3.7.10
List of nitrates: 1.19
Reactions of nitrates: 12.11.2
Reduce nitrate to ammonia:
Tests for nitrates / nitrites with dipsticks:
Tests for nitrates:

Nitric acid, HNO3
Nitric acid: 12.5.0
Nitric acid with sulfuric acid: 12.5.3
Acid-base neutralization, acid with base forms a salt and water: 12.8.0
Acids with salts: 12.3.15
Aqua regia
Concentrated acids with metals, nitric acid with copper: 12.3.12
Concentrated acids with a non-metal, carbon: 12.3.14
Concentrated nitric acid as oxidizing agent: 15.2.5
Conservation of mass, copper cycle reactions: 12.1.3
Copper, brass and bronze alloys: 5.5.3
Dilute acids with alkalis:
Dilute acids with basic oxides: 12.3.5
Dilute acids with carbonates, common carbonates:
Dilute acids with sodium hydroxide:
Dilute hydrochloric acid with sodium carbonate:
Dilute nitric acid with carbonates and bicarbonates: 12.3.15
Dilute nitric acid with copper:
Dilute nitric acid forms carbon dioxide: 12.3.15
Dilute nitric acid with metals: 12.3.13
Dilute nitric acid with metal oxides: 12.3.14
Group tests instructions:
Hydrogen peroxide, reducing agent: 12.12.5
Prepare dilute acids and bases: 3.4.3
Prepare nitric acid, sulfuric acid with sodium nitrate: 12.5.1
Prepare nitrogen dioxide, [nitrogen (IV) oxide, NO2]: 3.47.0
Properties of acids: 12.3.0
Reactions of the nitrites, NO2-: 12.11.1
Reactions of the nitrates, NO3-: 12.11.2
Prepare oxides by indirect oxidation, O2-: 12.12.2
Prepare sodium nitrate crystals: 12.1.16
Strong acids and weak acids:
Solubility tests, group analysis:
Separation into groups, metallic radicals):
Tests for zinc:, cobalt nitrate test
Thermal decomposition of acids: 8.2.4
Toxicity, Poisons and First Aid: 3.10.0.

Nitrile, organic functional group
Nitrile rubber, copolymer of acrylonitrile and butadiene
Nitrile chemical-resistant gloves
Protective clothing and equipment: 3.2.2.

Nitrobenzene, C6H5NO2, oil of mirhan, aromatic Nitro compounds:
Nitrobenzene, C6H5NO2, mononitrobenzene, pale yellow, oily liquid, unpleasant almond odour, poisonous, r.d. 1.2, b.p. 211oC.
Highly toxic by all routes of exposure, possibly carcinogenic.
Avoid inhaling vapour and skin contact so use small quantities < 25 mL or g in a well-ventilated area.
Nitrobenzene may be explosive when heated.
A solution / mixture < 0.1% is NOT hazardous.

Nitrogen, N
See: Nitrogen Elements, Compounds, (Commercial)
Nitrogen, Table of Elements
Nitrogen properties:
Nitrogen, Carbon / nitrogen ratio, C/N ratio: 9.14.3 (Agriculture)
Nitrogen compounds, one atom of nitrogen: 16.2.4
Nitrogen compounds, two or more nitrogen atoms:
Nitrogen-fixing bacteria: 4.12.3
Nitrogen-free mineral salts agar medium: 9.2.27
Nitrogen cycle: 6.39
Nitrogen deficiency: 1.10.0 (Agriculture)
Nitrogen deficiency symptoms: 1.1.4
Nitrogen, molecular weight, Density, (Table)
Nitrogen gas: 13.1.24
Nitrogen gas, motor car airbag, sodium azide: 13.9.3
Nitrogen pollution: 18.7.35
Tests for nitrogen compounds in food, soda lime test: 9.138
Tests for nitrogen in an organic compound, Kjeldahl method: 16.6.9.

Denitrifying bacteria, denitrifiers, denitrification: 4.12.4
Nitrifying bacteria, nitrification: 4.12.1
Prepare nitrogen gas, N2: 3.46.

Nitrogen compounds
Acid rain and nitrogen oxides, NOx: 3.48
Ammonia and the ammonium ion, NH3, NH4+: 12.11.3
Chemical fertilizers: 6.17.0
Nitric oxide, NO
Nitro, -NO2
Nitroalkanes (nitroparaffins):
Nitrocellulose, guncotton:
Nitrogen compounds, one atom of nitrogen: 16.2.4
Nitrogen compounds, 2 or more nitrogen atoms:
Nitrobarite, barium nitrate
Nitrogen dioxide, NO2
Nitrogen monoxide (nitric oxide), NO
Nitrogen monoxide (nitric oxide), NO: 13.1.25
Nitrogen oxides, Acid rain, NOx: 3.48
Nitrogen trichloride, Chloramines, pools: 18.7.23
Nitrogen triiodide, NI3:
Nitroglycerine (UK), nitroglycerin (USA), Explosive if dry, Not permitted in schools:
Nitrous acid
Nitrous oxide (dinitrogen monoxide), N2O: 13.1.27
Nitroso-beta-naphthol, Tests for cobalt:
Nitrosamines (See 9.): 12.11.1
Reactions of nitrates, NO3-: 12.11.2
Reactions of nitrites, NO2-: 12.11.1
Reactions of nitrites :12.11.1.

Nitric oxide, NO, nitrogen monoxide
Catalytic conversion of nitric oxide: 3.44.1
Prepare nitric oxide (nitrogen monoxide, NO): 3.44.

Nitrile, organic chemistry -CN group (-CN is inorganic compound cyanide), (cyano group, cyanides, cyanide ion, CN-),
See diagram: Nitrile
4-(Methylsulphinyl)butanenitrile, C5H9NS
Glucobrassicin (C16H19N2O9S2)
Nitrile butadiene rubber, NBR (chemical composition uncertain), resistant to oil and chemicals, do not use these gloves with fuming
concentrated nitric acid
Nitriles, acid nitriles, alkyl cyanides:
Chemical compounds in boiled brussels sprouts
Butane nitrile, C4H7N, CH3CHCH3CN
2-Phenylacetonitrile, C8H7N, C6H5CH2N,
3, 3'-Diindolylmethane, C17H14N2. broccoli, cabbage, kale, anti-tumor properties
3-Butenylnitrile, C4H5N, in brassicas, mustard oil
Ascorbigen, C15H15NO6, in Bitter melon.

Indole-3-acetonitrile, C10H8N2
Indole-3-acetonitrile, C10H8N2, 3-indoleacetonitrile, (3-indolyl)acetonitrile, light induced inhibitory substance in light grown cabbage,
Brassica oleracea, used in pesticides, potential cancer imaging agents.

Nitrogen dioxide, NO2
Nitrogen dioxide: 13.1.23
Prepare nitrogen dioxide, [nitrogen (IV) oxide, NO2]: 3.47.0
Pass nitrogen dioxide through water: 3.47.1.

Nitrous acid
Heat nitrous acid: 12.7.3
Ionization of nitrous acid: 12.5.02
Nitrous acid: 12.7.0
Nitrous acid, oxidizing or reducing agent:
Nitrous acid with amines: 12.7.2
Prepare nitrous acid: 12.7.1
Reactions of urea with nitrous acid: 16.6.15
Nitrites (NO2-):
See: Nitrite Elements, Compounds, (Commercial)

Nitrous oxide
Nitrous oxide (dinitrogen monoxide), N2O: 13.1.27
Nitrous oxide sniffing: 3.45.2
Prepare nitrous oxide (dinitrogen oxide, N2O): 3.45
Tests for dinitrogen oxide (nitrous oxide) N2O: 3.45.1.

Nobelium, No
, No (Alfred Nobel, 1833-1896, Sweden, invented dynamite, bequested Nobel prizes), radioactive actinide.

Metals, non-metals, transition metals: 7.3.0
Non-metal oxides (acidic oxides): 12.17.3
Non-metals: Table of the elements
Dilute acids with non-metals, carbon, sulfur: 12.3.4
Metalloids: 2.8.0
Patterns in the periodic table: 1.10.2, (See: 4.)
Properties of non-metals: 7.3.2
Reactions of non-metals with water:

Nutrient solutions, nutrients, nutrition
Nutrient agar medium: 9.2.33
Nutrient broth medium: 9.2.20
Nutrient broth, Micro-organisms: 4.3.11
Nutrient gelatin: 9.2.29
Nutrients in food: 19.3.13
Nutrients, Lost nutrients in food: 19.3.03
Nutrients, Plant nutrients: 6.36
Nutrient cycles: 6.44
Nutrition from the soil: 6.37.1.

Nylon polyamide:
Nylon thread, 0.4 mm
Nylon, Burning test, easy to ignite and forms a clear melt, blue flame with a yellow tip, does not burn after removing flame, burnt
vegetation smell
Aramids, plastic, nylon 6, 6, (C12H26N2O4)n
Prepare nylon polymer: 3.4.7
Tests for plastics: 3.102
Electrophorus: 31.6.0
Electrostatic series, Nylon stocking: 31.1.02
Polyamides: 3.7.6.

3.48 Acid rain and nitrogen oxides, NOx
Acid rain
Nitrogen oxides are produced naturally by decomposition, bacterial nitrification and lightning.
They are produced artificially by coal-fired power stations from coal and by oil-fired power stations.
When fuel burns at high temperatures in internal combustion engines, the nitrogen and oxygen of the air combine to form nitrogen oxides.
These oxides dissolve in water to produce the dilute nitric acid that is one component of acid rain.
Rain water pH = 5.6, acid rain pH < 5. N2 (g) + O2 (g) --> 2NO (g) nitric oxide.

Nitrogen oxides, abbreviated as "NOx", are mainly as follows:
1. colourless nitrogen oxide, NO (nitric oxide),
2. brown-red nitrogen dioxide, NO2 [nitrogen (IV) oxide] in equilibrium with dinitrogen tetroxide, N2O4 (2NO2 < = > N2O4) with
a pungent irritating odour, and
3. colourless dinitrogen oxide, N2O (nitrous oxide).
Nitrogen oxides are produced naturally by decomposition, bacterial nitrification and lightning.
They are produced artificially by coal-fired power stations from coal and by oil-fired power stations.
When fuel burns at high temperatures in internal combustion engines, the nitrogen and oxygen of the air combine to form nitrogen oxides.
These oxides dissolve in water to produce the dilute nitric acid that is one component of acid rain.
Rain water pH = 5.6, acid rain pH < 5. N2 (g) + O2 (g) --> 2NO (g) nitric oxide
2NO (g) + O2 (g) --> 2NO2 (g)
4NO (aq) + O2 (aq) + 2H2O --> 4HNO3 (aq)
2NO2 (g) + H2O (l) --> HNO2 (aq) + HNO3 (aq)
N2 (g) + 2O2 (g) --> 2NO2 (g) nitrogen dioxide
2NO2 (g) + H2O (l) --> HNO2 (aq) + HNO3 (aq) nitrous acid + nitric acid
HNO2 (aq) + heat --> HNO3 + 2NO + H2O (l)
4NO (g) + 3O2 (g) + 2H2O --> 4HNO3.

3.44 Prepare nitric oxide (nitrogen monoxide, NO)
See diagram 3.44: Preparing nitrogen monoxide | See diagram 1.13a: Simple fume hood
A pinch tap, B one-hole stopper, C copper pieces, D rubber gasket with holes, E dilute nitric acid
Be careful! Prepare nitric oxide only in a fume hood or fume cupboard, or use small quantities near an open window or a
well-ventilated area.
Use eye and skin protection when splashes are possible.
Nitrogen monoxide, NO, is a colourless toxic gas that reacts immediately with oxygen in the air to form brown fumes of nitrogen
dioxide, NO2.
Nitric oxide has many physiological functions in the body, e.g. dilation of blood vessels.
Nitrogen monoxide is a colourless gas that forms brown fumes of nitrogen dioxide, NO2 in air.

1. Do this experiment in a fume cupboard, fume hood or near an open window.
Add drops of dilute nitric acid to copper.
Nitrogen oxide forms that immediately reacts with oxygen in the air to form nitrogen dioxide.

2. Do this experiment in a fume cupboard, fume hood.
Fit each end of a glass tube, diameter 2 cm and length 15 cm, and with two one-hole stoppers fitted with short delivery tubes.
Connect one delivery tube to a short rubber tube with a pinch tap on it.
Fix a 2 cm rubber gasket with holes drilled in it in the middle part of the glass tube.
Drop pieces of copper on the rubber gasket.
Remove the stopper from the other end of the glass tube and add dilute nitric acid, i.e. 1 to 3 ratio of concentrated nitric acid to water.
Add enough diluted nitric acid so that no space is left for an air bubble after replacing the stopper.
Invert the apparatus and clamp it vertically with a container under the glass tube.
During the reaction the colourless gas produced gradually presses the solution out of the tube.
When the copper pieces are no longer in contact with the nitric acid solution the reaction stops leaving nitrogen oxide in the upper
portion of the glass tube and a blue solution in the small container.
Open the pinch tap to let air enter the tube and note the oxidation to form brown fumes of nitrogen dioxide.
The level of the solution rises to show that nitrogen dioxide dissolves in water.
To prevent air contamination, absorb the nitrogen dioxide in the tube with an alkali solution.
3Cu (s) + 8HNO3 (aq) --> 3Cu (NO3)2 (aq) + 4H2O (l) + 2NO (g)
2NO (g) + O2 (g) --> 2NO2 (g), [The O2 comes from the air.]
3. Repeat the experiment with cold 7M nitric acid.

4. This experiment may be done in a syringe.
Add 5 mL of 1.2 M solution of FeSO4 in 1.8 M H2SO4 to 0.27 g of solid NaNO3.
The reaction mixture turns black and nitric acid gas is produced.
Wash the gas through deionized water.
NO2- + Fe2+ (aq) + 2H+ --> NO (g) + Fe3+ (aq) + H2O

3.44.1 Catalytic conversion of nitric oxide (nitrogen monoxide)
When the petrol and air mixture ignites in motor car engines, nitrogen and oxygen combine to form poisonous nitrogen oxide.
In a three-way catalytic converter fitted to a high performance motor car engine using unleaded petrol, carbon monoxide and unburned
hydrocarbons (Hcarb) combine with nitrogen monoxide over a platinum rhodium catalyst to form harmless gases.
2CO (g) + 2NO (g) --> 2CO2 (g) + N2 (g)
Hcarb (g) + NO (g) --> CO2 (g) + H2O (g) + N2 (g)
Hcarb (g) + O2 --> CO2 (g) + H2O (g): 16.1.14

3.45 Prepare nitrous oxide, (dinitrogen oxide, N2O)
(nitrous oxide, dinitrogen oxide, nitrogen (I) oxide, dinitrogen monoxide, laughing gas)
Be careful! Prepare nitrous oxide only in a fume hood or fume cupboard.
Dinitrogen oxide is a colourless gas that is soluble in water, with a sweet smell that does not change the colour of moist litmus.
It was previously used as an anaesthetic in dentistry ("laughing gas") and as a propellant in aerosol sprays.
Be careful! Do NOT inhale nitrous oxide.
It can cause death.
Be careful! If you heat ammonium nitrate to dryness, it may decompose with an explosion.
So heat the ammonium nitrate to between 170oC and 240oC and no higher to avoid detonation.

1. Put 2 g of ammonium nitrate in a dry large test-tube.
Fit a stopper with a delivery tube in the test-tube.
Heat the test-tube slowly and pass the gas formed through 5% iron (II) sulfate solution to remove any nitrogen monoxide.
Collect the gas in a receiving test-tube.

2. Heat 10 g sodium nitrate powder with 9 g ammonium sulfate.
Collect the gas by upward displacement of air.
NH4NO3 --> N2O + 2H2O.

3.45.1 Tests for dinitrogen oxide (nitrous oxide), N2O
Put a glowing splint down in the receiving test-tube and note the gas relights the splint.

3.45.2 Nitrous oxide sniffing
Courier Mail (Brisbane), August 29 2015
Nitrous oxide sniffing sparks ban from shops
Supermarkets have removed nitrous oxide canisters from their shelves because of the alarming trend of people using the gas to get high.
Pure nitrous oxide, normally used to charge whipped cream dispensers, cuts off oxygen to the brain when inhaled, resulting in fainting
and, in extreme cases, death.
Users get a euphoric high that lasts for about 20 seconds and users may become addictive to nitrous oxide.
Similar to laughing gas, which has been used in medical procedurs since the l9th century, the gas in the cartridges known colloquially as
"nangs" is far more potent.
Often users combine alcohol and cannabis with the nitrous oxide to give a better "high".
The cartridges are cheap and readily available at most convenience stores as "Cream bomb", "Soda bomb", "Soda whippper",
"Cream charger", "Whipped cream dispenser".
Also, such chargers may explode causing injury.
University of Queensland Professor and Director of the Centre for Youth Substance Abuse, Wayne Hall, said: "Inhaling large quantities
had potentially dire consequences."
He said: :Supermarkets had removed the gas cartridges from their shelves."
"In clinics, the level people inhale is typically about 3 per cent so this, being pure, is far more dangerous, " Prof Hall said.
"It depends on how it's being taken but if it's inhaled directly, that is pure nitrous oxide and that is very different to a controlled dose.
There are certainly health risks associated with it and while most people see it as a pretty innocuous thing they are getting involved with,
using large quantities of it makes neurological damage a possible outcome.
Retailers should be aware of what is going on.
I am sure they are not interested in having their products abused in this sort of way as well, " Prof Hall said.
The cartridges can also be bought in bulk online - a box of 400 sells for AUD 275.

3.46 Prepare nitrogen gas, N2
Atmospheric nitrogen cannot be used directly by the body.
Liquid nitrogen is used to freeze tissues for microscopic examination.
Nitrogen is colourless, odourless, tasteless, neutral and nonreactive.
Nitrogen does not support combustion but magnesium and
calcium will continue to burn in nitrogen to form nitrides.
Nitrogen is manufactured by fractional distillation of air.
Air contains about 78% of nitrogen.
Ammonium nitrite is unstable so the reaction of saturated solutions of sodium nitrite with ammonium chloride can be used to prepare
Be careful! This reaction can explode without warning.

1. Heat gently a test-tube containing 5 mL of saturated ammonium chloride solution.
Add saturated sodium nitrite solution drop by drop.
The reaction is exothermic, so stop heating when some gas forms.
The ammonium nitrite breaks down into nitrogen and water.
NH4NO2 (s) --> N2 (g) + 2H2O (l).

2. Dissolve 20 g of calcium hypochlorite (bleaching powder) in 100 mL water by shaking then filter the mixture.
Add 10 mL of concentrated ammonia solution to the calcium hypochlorite solution and heat the mixture.
Collect the gas by upward displacement of air.
Be careful! Chloramine and explosive nitrogen trichloride may be produced!
2NH3 + 3CaOCl2 --> N2 + 3H2O + 3CaCl2.

3. Invert a bell jar over a stand in water and insert lighted phosphorus into the bell jar.
Oxygen and phosphorus combine to form phosphorus pentoxide,
P4 + 5O2 --> P4O10
The phosphorus pentoxide is absorbed by the water in what may be a violent reaction to form phosphoric acid, leaving the nitrogen.
P4O10 + 6H2O --> 4H3PO4.

3.47.0 Prepare nitrogen dioxide, [nitrogen (IV) oxide, NO2]
Nitrogen dioxide is a brown gas with a choking smell that may irritate the lungs and lead to death.
It is commonly formed by the reaction of concentrated nitric acid with copper and the decomposition of metal nitrates and nitrites.
See diagram 1.13a: Simple fume hood
Be careful! Prepare nitrogen dioxide only in a fume hood or fume cupboard.
Liquid dinitrogen tetroxide, N2O4, b.p. 21.2oC, dissociates as a gas to form nitrogen dioxide, NO2.

1. Pour drops of concentrated nitric acid on pieces of copper in a test-tube.
Fix a stopper in the test-tube immediately because the brown noxious gas, nitrogen dioxide, forms with a pungent irritating odour.
The nitric acid acts as an oxidizing agent and is reduced to nitrogen dioxide and water.
Collect the gas by upward displacement of air in a fume hood.
Be careful! The reaction is exothermic.
Cu (s) + 4HNO3 (aq) --> Cu(NO3)2 (aq) + 2H2O (l) + 2NO2 (g).

2. Heat lead (II) nitrate crystals.
The decomposition may be noisy.
Nitrogen dioxide and oxygen form, leaving yellow lead oxide.
Pb(NO3)2 (s) --> 4NO2 (g) + 2PbO (s) + O2 (g)
lead (II) nitrate --> nitrogen dioxide + lead oxide + oxygen.

3.47.1 Pass nitrogen dioxide through water
Nitrogen dioxide is decomposed by water to form a mixture of nitric acid (HNO3) and nitrous acid (HNO2).
Note the colour and odour of the water.
Test the solution with litmus paper.
2NO2 + H2O --> HNO3 + HNO2.

12.9.4 Reactions of nickel compounds
1. Heat some nickel carbonate in a hard glass test-tube and note the green brown residue of nickel (II) oxide.
Heat the nickel (II) oxide in a crucible and black nickel (III) oxide, Ni2O3, forms.
Dissolve nickel (III) oxide in dilute sulfuric acid to give green nickel (II) sulfate.
2Ni2O3 + 4H2SO4 --> 4NiSO4 + 4H2O + O2.

2. Add sodium hydroxide solution to nickel sulfate solution.
Note the light green precipitate of nickel (II) hydroxide, that is stable in air and is soluble in ammonium hydroxide to give a blue solution
of a complex ion.
Ni2+ + 2OH- --> Ni(OH)2 (s).

3. Heat a solution of nickel chloride made by dissolving nickel carbonate in hydrochloric acid.
Nickel chloride crystals are stable when heated.

12.5.0 Nitric acid
Nitric acid itself formerly made from sodium nitrate, but is now manufactured from the nitrogen of the air.
Aqua fortis, formerly nitric acid, with HCl removes base metals from gold
Aqua fortis (strong water), former name for nitric acid, was used to dissolve all metals except gold, so it became the test for gold and
test that a gold sample was pure gold, called the acid test.
Nitric acid (concentrated), HNO3, is a yellow fuming corrosive liquid that dissociates into ions even in concentrated solution.
Concentrated nitric acid is a strong oxidizing agent.
Dilute nitric acid is a strong acid that reacts with metals as an acid or an oxidizing agent.
Nitric acid is a clear, colourless, fuming, unstable, corrosive, poisonous liquid).
For nitric acid, use only glass equipment, and attach corks and rubber tubing rapidly.
Nitric acid is both a strong acid and a powerful oxidizing agent.
It produces severe acid burns, and can explode when mixed with many combustible materials.
The vapour of concentrated nitric acid is strongly irritating to the lungs.
Spillage of concentrated nitric acid outside a fume cupboard will require evacuation of the area until fumes dissipate.
Use sodium bicarbonate to neutralize spills.
Avoid skin contact with nitric acid.
Prolonged contact with nitric acid causes severe chemical burns.
Nitric acid turns the skin yellow because of the nitration of aromatic amino acids, tyrosine, tryptophan and phenylalanine, in the protein
of the skin.
After a few days, the yellow layer peels off.
Wear a face shield when doing any experiments, e.g. pouring, which could result in splashing of the liquid.
Concentrated nitric acid can explode when mixed with methylated spirit, ethanol, methanol and other combustible materials.
The reaction of nitric acid with alcohols is especially violent.
Concentrated nitric acid boils and decomposes at 83oC.
The product of the reaction between concentrated nitric acid and cellulose (cotton, paper, wood) is very explosive.
Store concentrated nitric acid in the acid bay of the store room.
Dilute nitric acid may be stored safely in preparation rooms.
Do not store it near acetic acid.
The molar mass of HNO3 is 63.01 g / mol.

12.5.01 Grades of nitric acid
Nitric acid, concentrated, 16M, 95%, 130 mL of concentrated solution for 1 litre of 2 M solution.
Nitric acid, > 16 M (70%), fuming nitric acid (95%), Highly toxic by all routes, explosive mixture with alcohols and other organics,
highly corrosive (COR 2031), skin irritant, use in fume cupboard or small quantity in well-ventilated area.
Sold as: Nitric acid, ACS reagent, 90.0%, CAS Number 7697-37-2, HNO3,
Molecular Weight 63.01, EC Number  231-714-2, MDL number MFCD00011349, PubChem Substance ID 24855630
Nitric acid, corrosive if left on clothes.
Nitric acid, Neutralize spilled acid with with dilute ammonia solution, then test part affected with red litmus paper until it turns blue.
Nitric acid, < 16 M (70%), > 4M (24%), concentrated nitric acid (68%) Highly toxic and hazards as above,
Nitric acid, > 4M (24%), >2 M (1%), corrosive and skin irritant, dilute solutions < 1% only, Harmful if ingested
Nitric acid, < 0.2m (1%), Not hazardous.

Nitric acid grades
Some grades sold by Sigma-Aldrich chemicals:
Nitric acid puriss, p.a., ACS reagent, fuming, 99.5%
Nitric acid reagent grade, fuming, >90%
Nitric acid red, fuming, HNO3 >90 %
Nitric acid reagent grade, >90%
Nitric acid ACS reagent, 90.0%
Nitric acid, ACS reagent, 70%
Nitric acid 70%, AR grade
Nitric acid 70%, purified by redistillation, 99.999% trace metals basis Nitric acid 65%, TraceSELECT Ultra, for ultratrace analysis
Nitric acid 69.0%, TraceSELECT, for trace analysis
Nitric acid puriss, p.a., ACS reagent, ISO, 69%
Nitric acid puriss., 64-66%
Nitric acid purum p.a., 65% (T)
Nitric acid concentrate for 1L standard solution, 1.0 M HNO3 (1.0N).

1. Anhydrous nitric acid, 100% nitric acid, density 1.513 g / mL, approximately.
24 M, colourless liquid, 1.5222 g / cm3, b.p. 83oC.

2. White fuming nitric acid, WFNA (called "100% nitric acid")
Concentration close to anhydrous nitric acid, < 2% water, < 0.5% dissolved NO2.
It does not contain N2O4.
(Red fuming nitric acid, RFNA, contains 13% dinitrogen tetroxide, N2O4, and 3% water.
It was used as a rocket propellant.)

3. Fuming nitric acid, > 95%
Relative density 1.5, b.p. 83oC, miscible with water, strong oxidizing agent, yellow colour from the atmosphere.
Light causes photolytic decomposition of the colourless pure acid to form dinitrogen tetroxide that colours the acid yellow-brown.
As the acid darkens in light it may be stored in dark glass bottles.
Concentrations > 86% are commonly called "fuming nitric acid".
Boiling nitric acid
4HNO3 --> 2H2O + 4NO2 + O2 (72oC)
NO2 dissolves in the nitric acid to form fuming nitric acid, 16M, the most concentrated grade at STP.

4. Reagent grades, 70% reagent grades, e.g. "70% ANALAR" solution"
< 16 M, oxidizing acid, minimum assay 69%, relative density 1.41
Concentrated acid 70% by weight is very hygroscopic.
Use it to reacts with copper to form brown nitrogen dioxide.
If concentrated nitric acid of commerce has a relative density of 1.41 and mass per cent HNO3 = 69%
Compute the molal concentration of HNO3
Mass of one litre of concentrated nitric acid = 1410 g, of which (0.69)(1410 g) = 972.9 g HNO3 / L, the balance is water.
So 972.9/63.01 = 15.44 mol / L is the molar concentration.

5. Concentrated nitric acid (Technical grade), 68%
Approximately 15 molar, relative density 1.42, the maximum boiling azeotrope (constant boiling mixture), 68% nitric acid, 32% water,
at 120.5oC
Strong oxidizing agent, so metals dissolve in it and nitrogen oxides are formed.
Nonmetals react to form the oxo acid or oxide.

6. Dilute nitric acid, < 4 M (24%)
2.0 M and 1.0 M volumetric solutions
Use 1% (> 2M) acid to demonstrate metal activity and acid on carbonates.
Prepare nitric acid by action of sulfuric acid on sodium nitrate.
Prepare dilute acids
Use safety goggles and nitrile chemical-resistant gloves.
If technical nitric acid (70% w/w) has a molarity = 15.4 moles / L
1 litre contains 15.4 moles, so 1 mole is contained within = 1 litre / 15.4 moles.
1 mole = 0.0649 Litres = 64.9 mL
Mass of 64.9 mL of technical nitric acid: = 64.9 mL × 1.41g / mL
= 91.5 g, where 1.41g / mL is the density of the technicalnitric acid, 70% w/w
Add 64.9 mL, or 91.5 g, of technical nitric acid to water, make up to 1L, to prepare 1 M solution of nitric acid.
Nitric acid 2 M, Dilute 129.8 mL of 15.4 M acid (70% w/w, 1.41 g / mL) to 1 litre of water
Nitric acid 3 M: Dilute 194.7 mL of 15.4 M acid (70% w/w, 1.41 g / mL) to 1 litre of water.

7. Dilute nitric acid < 0.2 M (1%) Not hazardous
Technical solutions for use by tradesman to clean bricks are very weak solutions.

12.5.02 Ionization of nitrous acid
Ka = 4.5 × 10-4
HNO2 + H2O <--> H3O+ + NO2-
Nitrosamines, produced by nitrous acid with secondary amines, can be formed in the gut when nitrites react with amino acids.

12.5.1 Prepare nitric acid, sulfuric acid with sodium nitrate
Add concentrated sulfuric acid to sodium nitrate.
Be Careful! Heat gently, nitric acid vapour forms.
NaNO3 (s) + H2SO4 (l) --> HNO3 (l) + NaHSO4 (s)
Ionization of hydrogen sulfate ion
HSO4- + H2O <--> H3O+ + SO42-.

12.5.2 Nitric acid with copper
Nitric acid dissolves most metals, usually producing copious brown fumes of toxic nitrogen dioxide.
However, the composition of the gases produced depends on the concentration of the nitric acid.
The reaction of copper with dilute nitric acid produces colourless nitric oxide, NO, that reacts with air at the top of a test-tube to form
brown nitrogen dioxide, NO2.
With concentrated nitric acid, copper forms mostly brown NO2 gas.
Nitrogen dioxide is a powerful lung irritant and all reactions that result in the formation of nitrogen dioxide should be done in a fume
cupboard or a well-ventilated area.

12.5.3 Nitric acid with sulfuric acid
The stronger concentrated sulfuric acid donates a proton, H+, to the weaker concentrated nitric acid, which then loses a water molecule
leaving the electrophile NO2+.
HNO3 + H2SO4 --> NO2+ + H2O + 2HSO4-.

12.7.1 Prepare nitrous acid
Weak acid prepared by acids on nitrites.
barium nitrate + sulfuric acid --> barium sulfate + nitrous acid
Ba(NO2)2 + H2SO4 --> BaSO4 + 2HNO2
sodium nitrite + dilute hydrochloric acid --> sodium chloride + nitrous acid
NaNO3 (aq) + HCl (aq) --> NaCl (aq) + HNO2 (aq).

12.7.2 Nitrous acid with amines
nitrous acid + amines --> ionic salt in aqueous solution
nitrous acid + amines --> diazonium ion + chloride ion
HNO2 + R-NH2 --> R-N+N + Cl- (note triple bond)
nitrous acid + phenylamine --> benzenediazonium chloride + Cl-
HNO2 + C6H5NH2 --> C6H5N2Cl + 2H2O
Diazonium ion, C6H5N2+, forms unstable salts.
Alkyl diazonium ions are unstable and rapidly decompose, but aryldiazonium ions are more stable if kept in solution below 10oC, but
as solids they are explosive.

12.7.3 Heat nitrous acid
Heated nitrous acid decomposes to form nitric acid and nitrogen monoxide (nitric oxide).
nitrous acid --> nitric acid + nitrogen monoxide
2HNO2 --> HNO3 + NO.