Chemistry topics, H

School Science Lessons
Topic Index H
2024-06-19

Chemistry, H
Contents
Haber process, Prepare ammonia
Haemagglutinins
Haematite, hematite, (Geology)
Haematoxylin, Prepare
Haeme, heme
Hafnium, Hf
Hair
Halides, Tests, (Experiments)
Halite, rock salt, (Geology)
Halloysite, (Geology)
Hallucinogenic drugs
Halogens
Halon-1211
Halon-1301
Hamamelose
Hand warmers, Iron powder
Handling and transferring chemicals, (Experiments)
Hands-on science activities
Hanksite
Hardness, (Experiments)
Harpagoside
Harmaline
Harman
Harmful substances
Harmine
Hartshorn, (deer antlers)
Harzianopyridone
Hassium, Hs
Haupt's adhesive, Prepare
Hausmannite, (See: Rhodonite), (Geology)
Hazards, health hazzards
HDPE, Plastics recycling code
Health effects of chemicals
Health salts
Heat
Heat of, (Experiments)
Heat up, (Experiments)
Heat treatment of metals
Heat, Tests for heat, (Experiments)
Heat of neutralization reactions, (Experiments)
Heating fats
Heavy metals
Heavy water
Hectopascal
Hederagenin
Hederin, Alpha-Hederin
Heelball (wax)
Heliosupine
Heliotridine
Heliotrine
Helicoside
Helium, He
Helmets, Safety
Hemagglutinins
Hematine, ferrite magnets
Hematite, haematite, (Geology)
Heme, haeme
Hemicellulose, Cellulose
Hemiterpenes
Hemiterpenoids
Hentriacontane
Heparin
Heptane
Heptanoic acid, (See: Lipitor)
Heptanone
Herbacetin
Herbal solutions, Prepare
Herbal tinctures, Prepare
Herbicides, weedicides
Hernandulcin
Herniarin
Heroin
Hesperidin
Hess's law
Heterodendrin
Hexene
Hexanol
Hexane
Hexa-
Hexose sugars
Hexyl bromide
HFCS, invert sugar, Prepare
High risk substances
High toxicity chemicals
Hinokitiol
Hispidulin
Histamine
Histamine, Antihistamines
Histidine
Hofmann voltameter, Electrolysis of water
Holmium, Ho
Honey, honeybee
Homostachydrine, (See: Betaines)
Honokiol
Hordenine
Horn
Horneblende, (Geology)
Horseshoes, from a low carbon steel alloy (A-36), MP about 1500 oC
Hot ice, frozen CO2
Hotplates, stirrers
Household, home, kitchen items
HPLC, High-performance liquid chromatography
Humectants
Humilixanthin
Humulene
Humulone
Huperzine
Hyalite, (See: Silicates), (Geology)
Hyaluronic acid
Hydrastine
Hydrates, decomposition
Hydraulic fluid
Hydrazine, N2H4
Hydrides
Hydriodic acid
Hydrobromic acid
Hydrocarbons, Hydrocarbyl groups
(Experiments)
Hydrocarbons, Saturated
Hydrocarbons, Unsaturated
Hydrochloric acid, HCl
Hydrocolloids
Hydrocortisone
Hydrozincite
Hydrogen, H
Hydrogen gas
Hydrogen bromide, HBr
Hydrochloric acid, HCl
Hydrogen cyanide, HCN
Hydrogen fluoride, HF
Hydrogen sulfide, H2S
Hydrogencarbonate, (-HCO3^-)
Hydrogenation
Hydroiodic acid, a strong acid
Hydrolysis of: (Experiments)
Hydrophilic substances
Hydroxides, Decomposition
Hydroxy compounds
Hydroponics
Hydroquinone
Hydrated salts, water of crystallization
Hydroxides
Hydroxyglucobrassicin
Hydroxylupanine
Hydroxystachydrine
Hydroxonium ion, H3O⁺, hydroxonium ion
Hydroxyapatite
Hydroxybenzaldehydes
Hydroxybenzoic acids
Hydroxybenzoketones
Hydroxybutanoic acid, Malic acid
Hydroxycinnamic acids
Hydroxygeraniol
Hydroxyphenylacetic acids
Hydroxyphenylpropanoic acids
Hydroxyphenylpropenes
Hydroxyl, hydroxide
Hydroxykynurenic acid
Hydroxypropionic acid, Lactic acid
Hydrozincite
Hygrine
Hygroscopic
Hyoscine, Scopolamine
Hyoscyamine
Hypaconitine
"Hyperactive", Food allergies and intolerances
Hyperforin
Hypericin
Hyperin
Hypnotics, Benzodiazepines
"Hypo", sodium thiosulfate
Hypochlorite ion: ClO^-, Chromium (III) hypochlorite
Hypobromous acid, (Swimming pools), Bromine products
Hypochlorite, ClO^-
Hypochlorous acid, (swimming pools)
Hypolaetin

Haeme
Haeme, (Heme), Haemoglobin, (Hemoglobin)
Haemoglobin is the protein that carries oxygen in the blood.
The haem group causes the red colour of blood.
The different kinds of haem are Haeme A, B, C and O.
Haeme A is a cytochrome oxidase ligand complex, C49H56O6N4Fe, a tetradentate ligand.
The most common type is Haeme B, C34H32O4N4Fe,
Haeme: See diagram 16.3.5.2.1
The "quaternary proteins" have four joined tertiary proteins, e.g. haemoglobin.
The "transition metals" form complex ions and often have catalytic activity, e.g. Fe in haemoglobin molecule.
Porphyrin chelates include haeme, in haemoglobin, bonded to iron (II) ion, and chlorophyll bonded to Mg (II) ion.
Carbon monoxide, CO, toxicity and air pollution: 3.39.0 (See 1.)
Danger of vehicle exhausts, tailpipe gases: 18.6.3
Ferratin
Fibrous proteins and globular proteins: 16.3.6.0.2, (See 2.)
Glycosylated haemoglobin: 8.0
Iron: 7.2.2.21
Luminol tests for blood: 14.3.1
Legheamoglobin
Porphyrins, porphine
Tests for haemoglobin, Hematrace test: 9.184
Tests for glucose, Glycosylated haemoglobin test: 8.0
Tests for haemoglobin, Hematrace test: 9.184
Tetrapyrroles
TMB test for blood: 9.183

Hair
Green hair and faded hair from swimming pools: 18.7.15.1
Hair hygrometer: 37.9.2
Hair and hair products: 19.7.3
Permanent crease solution: 19.5.6
Hydrogen peroxide on hair: 17.3.1.8
Our skin and hair: 2.19, (Primary)

Hafnium, Hf
See: Hafnium, Table of the Elements
See: Hafnium, RSC
Hafnium, Hf (Latin Hafnia, former name of Copenhagen), transition metal, abundant, space science heat resistance
It occurs in zirconium minerals, and in filaments for electron emission.
Hafnium boride, B2Hf
Hafnium (IV) n-butoxide, C16H36HfO4
Hafnium (IV) carbide, CHf
Hafnium (IV) oxide, HFO2, in computer transistors, smart phones
Hafnium (IV) sulfate, HfS2O8
Hafnium (IV) trifluoromethanesulfonate hydrate, C4F12HfS4O12.xH2O

3.4.9 Handling and transferring chemicals, Adding chemicals to containers
When adding chemicals to a reaction or container:
1. Students should not touch any chemical, but use a spatula or gloves, except for a few experiments when students are told to feel the texture of chemicals or minerals to determine whether they are crystalline or amorphous.
If students do touch any chemical, they should immediately wash their hands with soap and water.
2. The best way to add chemical to a container is to pour the powdered or crystalline chemical into a creased rectangle of clean paper, then tip the chemical from this paper held in a V- shape.
3. When taking chemicals from a container, after removing the stopper, keep holding the stopper in one hand so that you can replace it immediately afterwards.
This method ensures that the chemical does not have unnecessary exposure to air and that the correct stopper is replaced.
4. Transfer liquids through a funnel or pour the liquid slowly down a glass rod.
5. Fill pipettes with a pipette-filler and not by sucking by mouth.

Hardness
1. Hard substances
To "harden" cement is to let it become "rock hard".
34.10 Mohs' scale of hardness (Geology)
Hooke's law: When a big stress results in a small strain, the material is "hard".
34.5.1.1 Hooke's Law, elastic limit, stress and strain
Case-hardening (of steel)
Tests for hardness of lead, tin, and tin alloys: 3.62
2. Hardness of water, hard water
12.5.0 Hardness in water, water hardness
18.7.46 Magnesium hardness, (Swimming pools)
Prepare hard water: 12.5.4
Remove water hardness: 12.5.5
Soften hard water by boiling: 12.5.6
Soften hard water using chemicals: 12.5.7
Tests for water hardness: 12.4.0
18.7.16 Total dissolved solids, (TDS), water hardness, scale

Hassium, Hs
Hassium, Table of the Elements
Hassium, RSC
Hassium, Hs (Hassia, laboratory at Hesse, Germany), radioactive transuranic element

Hazards, Health hazards, Harmful substances
19.2.0 Food allergies and intolerances, "hyperactive"
Health risk = Food additives that may cause medical conditions
3.5.0 Hazards, chemical hazards, physical hazards
15.1.0 Hazards: Explosive, Flammable, Oxidizing, Poison, Harmful, Corrosive, Irritant
Health effects of chemicals
3.0.0 Health effects of chemicals, (List)
5.0.0 Health hazards, (List)
7.2.0 Radiation hazards
2.0.0 Physical hazards

Heat
Heat substances
Heat sources
Heat (Physics)
Heat of (reaction, enthalpy, calorimeter) (Chemistry), (Experiments)
Heat up (apply heat to something) (Chemistry), (Experiments)
34.9 Heat treatment of metals
Heat, Tests for heat, (Experiments)
Heat of neutralization reactions, (Experiments)

Heat of
Heat of reaction Thermochemistry,
Heat of, enthalpy, Calorific value: 4.38
Calorimeters, Specific heat capacity: 22.5.0
Chemical potential energy, enthalpy: 7.9.14.1
Energy of reactions, enthalpy, Hess's law: 14.01
Exothermic reactions, give out heat energy: 14.1.0
Heat of combustion, bomb calorimeter: 22.5.7
Heat of displacement, zinc with copper sulfate: 14.1.6
Heat of crystallization, heat of fusion: 24.1.9
Heat of neutralization with a calorimeter: 14.1.5
Heat of neutralization titration: 12.8.6
Heat of neutralization reactions: 3.82
Heat of reaction: 14.06
Heat of reaction, metals displace copper: 3.83
Heat of reaction, KMnO4 with glycerol: 14.1.7
Heat of rusting, steel wool: 14.1.4
Heat of solution: 3.17
Heat of solution of anhydrous CuSO4: 14.1.1
Heat pack, Sodium acetate heat pack: 14.1.11

Tests for heat
Tests for heat, heat-sensitive paper: #5.3.10H">5.3.10
Heat of reaction, chromium (VI) oxide with ethanol: 14.1.9
Heat of reaction, potassium permanganate with ethanol: 14.1.8
Heat of reaction, potassium permanganate with glycerol: 14.1.7
Heat of reaction, potassium with diethyl ether: 14.1.10

Heat up
Heat up, apply heat to something
Heat and temperature: 4.37
Prepare carbon dioxide: 3.2.0
Heat citric acid to form carbon: 12.6.2
Heat copper wire with iodine crystals: 12.2.2.2
Heat different substances (Primary): 2.21
Heat nitrogen tetroxide: 17.5.6.2
Heat fats, Smoke Point, Flash Point, Ignition Temperature, P/S Ratio: 3.9.5
Heat food with copper (II) oxide: 9.9.2
Heat hydrated iron chlorides: 14.8.30
Heat hydrogen bromide: 12.19.9.3a
Heat hydrogen carbonates: 13.7.7
Heat steel wool with iodine crystals: 12.2.2.3
Heat iron with sulfur: 12.2.2.1
Heat nitrogen tetroxide: 17.5.6.2
Heat sodium bicarbonate: 12.1.17
Heat hydrogen carbonates: 12.16.4
Heat sodium bicarbonate: 12.1.17
Heat sodium carbonate crystals: 12.1.24
Heat sodium thiosulfate crystals: 12.1.39
Heat sources: 8.1.0
Heat substances, sublimation, melting, decrepitation: 12.11.3.4
Heat substances that decompose when heated: 8.4.0
Heat sulfur to form sulfur dioxide: 8.2.15
Heat treatment of steel needles, annealing: 34.2.2
Heated air expands in a balloon: 20.1.1.2

Heavy metals
Heavy metals and "Chemical safety in schools": 7.9.31
Heavy metals safety: 7.9.31.1
Heavy metals recycling: 7.9.31.2
Heavy metals: 2.7.0 (Table of elements)
List of heavy metal compounds: 1.14

Helicoside
Helicoside, C29H36O17, phenylpropanoid, monomethoxyflavone, enzyme activities, anti-inflammatory, anti-asthmatic
It occurs in Che Qian Zi, (Plantago asiatica)

Helium, He
See: Helium, Table of Elements
See: Helium, RSC
Helium
Helium, He, (Greek helios sun, because emission line in sun spectrum), colourless, odourless, lightest noble gas, low cost, from party supplies shops (e.g. helium balloons)
Helium is a non-metal noble gas (inert gas), at room temperature and pressure.
Helium has no known compounds.
Helium has separate small molecules, 0.0005% of the air, superfluid at 2.2 K, lowest boiling point, and is obtained from natural gas wells.
It is used in diving gases, party balloons.
(Party balloons may travel over the oceans to fall and choke sea animals.)
Inert properties and high heat transfer make helium useful for welding as a shielding gas to protect the weld from oxygen and water when welding Cu, Mg alloys, and Al.
Large concentration of helium can asphyxiate, change of pitch of voice due to increased velocity of sound.
Helium has the lowest critical temperature, -268^oC.
Packaging gas, propellant gas E939. vapour density 0.14 compared to air
Atomic number: 2, Relative atomic mass: 4.00260, RD 0.147(4 K), MP = -270^oC, BP = -269^oC.
Specific heat capacity: 5.19 × 10³ J kg^-1 K^-1
Balloon as a sound lens, acoustic lens: 26.7.3
Balloon electroscope: 31.3.6
Critical point, critical temperature: 24.1.07, (See: Helium)
Density of gases, Helium (Table)
Helium balloon in a motor vehicle: 16.1.2.4.3
Helium, E939 Helium, (packaging gas, propellant)

Hentriacontane
Hentriacontane, n-Hentriacontane, Untriacontane, C31H64, CH3(CH2)29CH3, long-chain alkane hydrocarbon, antitubercular
It occurs in beeswax, peas (Pisum sativum), gum arabic Acacia senegal, Gymnema sylvestre, European black elderberry Sambucus nigra
Hentricontanol, Hentriacontan-1-ol, C31H64O, primary alcohol, (derived from hentriacontane hydride)

Heparin, C26H41NO34S4
Heparin, sulfated glycosaminoglycan, injectable anticoagulant
Heparin sulfate is a glycosaminoglycan covalently attached to core proteins to form proteoglycans.
It is produced primarily by mast cells in connective tissue and basiphils.
Enoxaparin, C26H40N2O36S5, low molecular weight injectable heparin, Xaparin

Ethyl butyl ketone, C7H14O
Ethyl butyl ketone, 2-Heptanone, C7H14O, CH3(CH2)4COCH3, ethyl butyl ketone
It is a colourless, flammable liquid, mild banana-like fruity odour, slightly soluble in water, soluble in organic solvents, irritant, floats on water.
It is used as solvent, ingredient in fragrances, synthetic flavouring, and occurs in garden mint.

Hexa-
Hexachlorobenzene, Lindane: 4.3.3
Hexachloroplatinic acid, H2PtCl6.6H2O
Hexadecan-1-ol, Cetyl alcohol: Cetyl alcohol
Hexadecanoic acid, CH3(CH2)14CO2H, palmitic acid, saturated fatty acid, palm oil, palm kernel oil, coconut oil, animals and plants
Hexahydrobenzene, C6H12, cyclohexane, hexahydrobenzene, colourless liquid, ethereal odour, toxic, Highly flammable
Hexahydrophenol, C6H11OH, cyclohexanol, cyclohexyl alcohol, hexahydrobenzene, hexalin, toxic
Hexahydrothymol, C10H20O, menthol
Hexamethyl diisocyanate, OCN(CH2)6NCO, HMDI, 1,6-diisocyanatohexane, polyurethane adhesive or surface coating, irritant
Hexanal, C6H12O, hexaldehyde (used to prepare fruity flavours)
Hexane, C6H14

Hexanoic acid, C6H12O2
Hexanoic acid, caproic acid, hexoic acid, hexylic acid, C6H12O2 or CH3(CH2)4COOH, straight-chain medium-chain saturated fatty acid
It is a white crystalline solid or colourless to light yellow oily liquid, unpleasant odour like cheese, irritates skin, eyes and mucous membranes, toxic.
It is used to make perfumes, as an acidulating agent in foods, animal fats and oils.
It occurs in goat fat, Cocos nucifera and other palm oils, as glucose ester in Datura, non-toxic medium chain triglycerides, foods, drugs, and cosmetics

Hexanol, C6H14O
Hexanol, C6H14O, CH3(CH2)5OH, CH3(CH2)5OH, CH3(CH2)4CH2OH, n-hexanol, hexyl alcohol, n-hexyl alcohol, 1-hexanol, (pharmacy preparations), toxic, flammable
Hexan-1-ol, Solution < 25% Not hazardous

Hispidulin, C16H12O6
Hispidulin, Dinatin, Scutellarein 6-methyl ether, a trihydroxyflavone, apoptosis inducer, anti-inflammatory, antioxidant, anticonvulsant, antineoplastic, irritant.
It occurs in Citrus sidachii, Digitalis orientalis, Grindelia argentina, Arrabidaea chica, Saussurea involucrate, Crossostephium chinense, Artemisia species.

Holmium, Ho
See: Holmium, Table of the Elements
See: Holmium, RSC
Holmium, Ho, (Latin Holmia, Stockholm), silver metal lanthanide, rare earth
Holmium chips, foil, ingot, Ho
Holmium (III) acetate hydrate, C6H9HoO6.xH2O
Holmium (III) bromide, (Br3Ho
Holmium (III) chloride, Cl3Ho
Holmium (III) chloride hexahydrate, Cl3Ho.6H2O
Holmium (III) fluoride, F3Ho
Holmium (III) nitrate pentahydrate, HoN3O9.5H2O
Holmium (III) oxide nanoparticles, Ho2O3
Holmium (III) perchlorate, H2Cl3HoO13
Holmium (III) phosphate, HoO4P
Holmium (III) sulfate, Ho2O12S3
Holmium (III) trifluoromethanesulfonate, C3F9HoO9S3

Honey
Float cork, wax and wood in different density liquids: 11.4.6.0, (See: 2.)
Rayleigh-Taylor instability: 13.4.6
Honeybee, Bees, honeybee
Experiments
Viscosity of honey: 17.3.20
Yeast population, bakers' yeast: 9.205, (See: 1.)
Use honey to condition hair and prevent split ends and frizzy hair, dress wounds and burns, with lemon soothe sore throat and relieve coughing, substitute for cooking sugar.

Honokiol, C18H18O2
Honokiol, small-molecule polyphenol, in Magnolia, with other polyphenols, e.g. Magnolol, antiangiogenic, antiinflammatory, antitumor, central muscle relaxation, inhibits thrombosis, scavenger for hydroxyl radicals, in Asian herbal teas, e.g. houpo and saiboku-tu

Household, home, kitchen items
Beauty and skin care products: 19.1.0
Cooking: 19.2.0
Food
Household chemicals 1: 19.3.0
Household chemicals 2: 19.1.0
Household fabrics: 19.4.0
Household products: 19.5.0
Kitchen scale, Single pan balance: 3.19
Microwaves, microwave cooking: 19.3.5

HPLC
HPLC, High-performance liquid chromatography, high-pressure liquid chromatography, used to separate and identify components in a mixture,
may show concentration, e.g. 16.3.6.7 [6]-Gingerol = 95% (HPLC)

Humulone, C21H30O5
Humulone, (α-lupulic acid), cyclic ketone, an aromatic ketone, bitter, antibacterial, antioxidant
It occurs in hops (Humulus lupulus) resin
See diagram 16.1.1.2.2: Humulone

Hydrazine, N2H4
Hydrazine, diazine, toxic by all routes
Hydrazine hydrate, NH2NH2.xH2O, hydrazine monohydrate, toxic
Hydrazine hydrate, Solution < 1%, Not hazardous
Hydrazine hydrochloride, NH2NH2.HCl hydraziumchloride, hydrazine monohydrochloride, toxic by all routes
Hydrazine sulfate, NH2NH2.H2SO4, hydrazium sulfate, toxic, reacts violently with oxidizing agents

Hydriodic acid, HI
Hydriodic acid, HI, conc. 5.5 M, solution <5 M (47%), toxic by all routes
Hydriodic acid is pure HI in water, but may be sold as 57%by mass Hydriodic acid, Solution < 1%, Not hazardous

Hydrobromic acid, HBr
Hydrobromic acid, bromic acid, hydrobromic acid solution, hydrogen bromide solution, 9 M (48%), toxic by all routes
Hydrobromic acid, Solution > 2M (10%), Not hazardous

Hydrocarbons
Hydrocarbons, hydrocarbon chains, -C-C-C-, bond angle 109.5^o, -CH2-CH2-CH2-
Hydrocarbyl groups, methyl -CH3. ethyl -C2H5, phenyl -C6H5
Hydrocarbon solvents, Flammable: 7.9.22, (See 6.)
Tests for gases from burning hydrocarbons: 16.4.6.0
Tests for unsaturated hydrocarbons: 9.4.9.0, acidified potassium manganate (VII) solution
Tests for unsaturated hydrocarbons: 9.4.8.1, alkaline potassium manganate (VII) solution
Tests for unsaturated hydrocarbons: 9.4.7.0, bromine water test
Tests for unsaturated hydrocarbons: 9.4.8.2, Baeyer's test
Tests for unsaturated hydrocarbons: 9.4.7.2, ignition test
See diagram 16.1.1: Alkanes, alkenes, alkynes

Hydrochloric acid, HCl
Hydrochloric acid is an aqueous solution of hydrogen chloride gas.
Hydrochloric acid dissolves most metals to form chlorides and hydrogen gas.
Hydrochloric acid is available as 5.0 M, 4.0 M, 2.0 M, 1.0 M and 0.5 M volumetric solutions.
Minimum assay 36% solution density 1.17 g cm^-3 at 20^oC
36% "ANALAR" solution
Hydrochloric acid is sold as "muriatic acid", and used in the building trades.
Hydrochloric acid, HCl: 11.0.0 Hydrochloric acid, HCl
Hydrochloric acid, (COR 1789), hydrochloric acid, 37%, spirits of salts, muriatic acid, spiritus salis
Hydrochloric acid, concentrated, 10 M, 35%, 200 mL of concentrated solution for 1 litre of 2 M solution
Hydrochloric acid, 37%, AR grade, CAS Number 7647-01-0, Molecular Weight 36.46 (1.19 g/mL, 12.08 M)
Hydrochloric acid, concentrated, > 10 M (32%), toxic, Corrosive, lung irritant
Hydrochloric acid, < 10 M (35%) > 4 M (14%), toxic, Corrosive, lung irritant
Hydrochloric acid, < 4 M (14%) > 0.2 M (1%), toxic, Corrosive, lung irritant
Hydrochloric acid, < 0.2 M (1%), Not hazardous, skin irritant
Hydrochloric acid, 3 M, dilute 258 mL of 11.6 M acid to 1 litre of water, 35% hydrochloric acid)
Hydrochloric acid, 4 M, dilute 400 mL of 10 M acid to 1 litre of water
Hydrochloric acid test, effervescence test: 35.1.8, (Geology)
Aqua regia, "royal water", dissolves gold (3 vols concentrated HCl + 1 vol concentrated HNO3)
Copper (II) sulfate solution with concentrated hydrochloric acid, ligand substitution: 1.1
Dilute hydrochloric acid with marble chips, balloons: 17.1.4
Dilute HCl with:
Muriatic acid
Prepare hydrogen chloride / hydrochloric acid: 3.42.0
Prepare hydrochloric acid with sodium chloride: 12.2.30

Rates of reaction of HCl
Reverse colour change, KI and HCl: 17.3.5
Sodium thiosulfate with dilute hydrochloric acid: 12.1.47
Titrate dilute HCl with NaOH, using a burette 1. 12.8.4.0
Titrate dilute HCl with NaOH, using a burette 2. 12.8.4.1
Tests for substances with dilute hydrochloric acid: 12.11.3.5
Tests for hydrogen chloride: 3.42.1.0
Tests for hydrogen gas: 13.4.4
Tests for hydrogen sulfide solution: 3.43.1

Dilute HCl with
Acids with sodium carbonate: 12.1.25
Calcium carbonate: 12.3.9.1
Galvanic cell, Voltaic cell: 33.84.1
Heat of neutralization reactions: 3.82
Hydroxides: 12.3.7.2
Metals, acids with metals: 12.3.2
Sodium carbonate: 12.3.9.1
Sodium hydroxide: 12.8.2
Sodium hydroxide, heat of neutralization: 14.1.5.1

Muriatic acid, HCl
Muriatic acid, hydrochloric acid, spirits of salt, acidum salis in hardware shops, builders for clogged drains, 37% muriatic acid (about 12 M), also use about 15%, for lowering swimming pool pH), about 30% for cleaning or etching concrete

Rates of reaction of HCl
Concentration of reactants, HCl with Mg: 17.2.2.1
Count bubbles, dilute HCl with Zn: 17.1.1
Gas burette, dilute HCl with marble chips: 17.1.3
Magnesium with HCl: 17.5.4.1
Particle size, dilute HCl with marble chips: 17.2.1
Volume of gas, dilute HCl with Zn: 17.1.2

Hyaluronic acid, (C14H21NO11)n
Hyaluronic acid, Hyaluronan, acidic, mucopolysaccharide, glycosaminoglycan, long unbranched polysaccharide, repeating disaccharide units, anionic
It occurs in nonsulfated glycosaminoglycan, in plasma membranes, in cartilage, and used for wound healing.
Hyaluronic acid sodium salt is obtained from from bovine vitreous humor.
(It fills the space between the lens and the retina within the eye.)

Hydrogen, H
See: Hydrogen, Table of Elements
Deuterium, isotope, ²H
Hydrogen bonds: 11.2.5
Hydrogen gas
Hydrogen bromide, HBr
Prepare hydrogen chloride / hydrochloric acid: 3.42.0
13.7.1 Hydrogen cyanide
Hydrogen fluoride, HF
Hydrogen sulfide, H2S
Hydrogencarbonate, (-HCO3^-)
Hydrogenation
12.19.6.1 Prepare hydrogen iodide, HI
Hydrogen peroxide
12.6.0.0 Hydrogen sulfate ion (HSO4^-), Sulfuric acid, ionization of hydrogen sulfate ion
16.6.19 Tests for hydrogen gas:
3.5.1 Hydrogen sulfide waste bottle

13.1.1 Hydrogen gas
Hydrogen, Table of Elements
13.4.1 Hydrogen gas, "Green" hydrogen gas generation
13.4.3 Prepare hydrogen gas
13.4.4 Tests for hydrogen gas
3.8.5 Hydrogen gas, hazards
13.4.2 Burn hydrogen gas
12.2.1 Acid-base reactions, (hydrogen ions, H+)
12.7.7 Alkalis with metals, sodium hydroxide, (See 2.)
12.3.4 Aluminium with acids, [3H2 (g)]
12.3.5 Aluminium with sodium hydroxide, [3H2 (g)]
12.3.2H Aluminium chloride with water, [3H+ (aq)]
Coal gas, (50% hydrogen gas)
12.4.8 Dilute acids with metals, hydrochloric acid, H2 (g)
8.0.0 Direct union of elements to form compounds, H2 +
12.12.10 Drain cleaners, + 3H2
15.5.4 Electrolysis of water
7.9.22 Flammable, (See: 4.)
7.9.28 Fuel cell, H2
33.1.3.11 Galvanic cell, Voltaic cell
14.1.10 Heat of reaction, potassium with diethyl ether
4.47 "Human" water (hydrogen boy, oxygen girl), (Primary)
11.2.5 Hydrogen bonds
33.1.7.5 Lemon cell
12.2.3.3 Metals displace hydrogen from acids
19.1.20 Packaging gases, E949
12.3.6 pH
13.4.3 Prepare hydrogen gas
12.15.3 Reactions of metals with steam
12.15.1 Reactions of metals with water
13.4.4 Tests for hydrogen gas
12.11.3.5 Tests for substances with dilute hydrochloric acid, (See: 2.)
Hydrogen bromide, HBr
13.7.1 Hydrogen cyanide
Hydrogen fluoride, HF

3.42.0 Hydrogen chloride / hydrochloric acid
Be careful!
Prepare hydrogen chloride gas, HCl, in a fume hood!
Hydrogen sulfide, H2S
Hydrogencarbonate, (-HCO3^-)
Hydrogenation
33.3.4 Lemon battery, lemon cell, electricity from a lemon
3.74 Metals displace hydrogen from acids
19.4.22 Packaging gases, E949
12.3.0.4 pH
13.4.3 Prepare hydrogen gas
12.15.3 Reactions of metals with steam
12.15.1 Reactions of metals with water
13.4.4 Tests for hydrogen gas
12.11.3.5 Tests for substances with dilute hydrochloric acid
13.5.1 Prepare hydrogen chloride
13.5.2 Prepare hydrochloric acid with sodium chloride
3.7.5 Decomposition of chlorides
14.0 Electrophiles and nucleophiles, HCl
12.19.5.0 CFCs, chlorofluorocarbons, "Freons"
Density of gases, Hydrogen chloride, (Table)
3.8.6 Hydrogen chloride, anhydrous, hazards
Experiments
31.1.3 Aluminium foil precipitator
3.6 Ammonium chloride smoke screen
10.1.3 Diffusion rates of ammonia and hydrogen chloride gases
17.5.5 Effect of temperature on chemical equilibrium
14.8.30 Heat hydrated iron chlorides
12.13.8 Phosphorus trichloride with water
12.19.8.3 Prepare iron (III) chloride, (See 2.)
12.20.2 Prepare tin (IV) chloride12.19.8.1 Reactions of sodium chloride
12.18.5.2 Sulfuric acid displaces acids from salts
18.6.0.3 Tests for air pollution from burning refuse
13.5.4 Tests for hydrogen chloride
12.11.3.6 Tests for gases with hot concentrated sulfuric acid
12.14.14 Zinc with copper in sulfuric acid

Hydrogen bromide, HBr
Heat hydrogen bromide: 12.19.9.3a
Prepare hydrogen bromide: 12.19.9.3
Reactions of hydrogen bromide: 12.19.9.4
Tests for substances hot conc. H2SO⁴: 12.11.3.6

Hydrogen fluoride, HF
Hydrogen fluoride, hydrofluoric acid, conc. 29 M, Very toxic, Not permitted in schools
Prepare hydrogen fluoride, HF: 12.19.7.1
Halide salts with hot conc. H2SO4: 12.19.3.1

13.1.3 Hydrogen sulfide
Acids react with sulfides to produce hydrogen sulfide, (rotten egg gas), and a salt.
Be careful!
Prepare hydrogen sulfide in a fume cupboard!
Coal gas
Density of gases, Hydrogen sulfide, (Table)
19.1.1 Hair products
3.8.7 Hydrogen sulfide, hazards
3.3.2 Hydrogen sulfide waste bottle
18.2.2.2 Iron in drinking water
8.4 Oxygenic phototropic bacteria
12.3.9 Acids with salts (See: with sulfides)
17.7.3 Hydrogen peroxide as oxidizing agent
15.5.7 Hydrogen sulfide as reducing agent
18.6.5 Smell of water, hydrogen sulfide, (rotten egg gas)
3.7.16 Sulfides, hazards
16.2.8.2 Sulfides: RSR (where R is not H)
Experiments
12.2.10.5 Heat iron with sulfur, synthesis reaction --> FeS
12.19.6.1 Prepare hydrogen iodide, HI (See 5.)
13.6.1 Prepare hydrogen sulfide
12.18.2.0 Prepare sulfides S2-, (See 3.)
5.32 Protect mangroves (See 5. ) (Primary)
18.6.5 Smell of water, hydrogen sulfide
13.6.2 Tests for hydrogen sulfide solution
11.3.3 Tests for solubility, prepare group analysis
12.11.3.5 Tests for substances with dilute hydrochloric acid
9.9.18.6 Use of freshwater algae for hydroponics

Hydrogencarbonate, (-HCO3^-)
Bicarbonate, hydrogen carbonate, HCO3^-, sodium hydrogen carbonate, bicarbonate of soda indicator solution
3.30.2Decomposition, hydrogen carbonates
Dilute acids with CaHCO3: 12.3.10.1
Dilute acids with NaHCO3: 2.3.10.0
Heat a hydrogen carbonate, NaHCO3: 12.16.4
Prepare carbon dioxide, NaHCO3: 3.34.2.0
Tests for bicarbonates: 12.11.5.4
Thermal decomposition, bicarbonates: 3.30.2

Hydrogenation
13.4.1 Hydrogen gas
Hydrogenation, cis-trans fatty acids: 3.9.8
Formation of alkanes: 16.4.1.1
Hydrogenation is a reduction reaction which results in an addition of hydrogen, H2.
Hydrogenated organic compounds become more saturated with hydrogen atoms.
For example, trans fatty acid (trans fat), is a fatty acid, formed as a result of hydrogenation.
Hydrogenation is the addition of hydrogen to a molecule to convert unsaturated organic molecules to saturated molecules and reducing double bonds to single bonds.
For example: (H2C=CH2 + H2) --> (CH3CH3)
alkene + hydrogen --> alkane

Hydrolysis of
Ammonium chloride: 12.10.3.2
Antimony chloride, reversible reactions: 17.5.5.2
Bismuth chloride, reversible reactions: 17.5.5.1
Esters, Hydrolysis of esters: 16.5.4
Ethyl acetate, autocatalytic hydrolysis: 17.3.15
Hydrolysis of starch by dilute HCl: 9.129
Hydrolysis of starch by salivary amylase: 9.130
Hydrolysis of sucrose by dilute acids: 9.131
Iron (III) chloride, iron chloride: 12.10.5
Salts: 12.10.3
Sodium hydrogen carbonate: 12.10.3.1
Starch by dilute hydrochloric acid: 9.129
Starch by salivary amylase (ptyalin): 9.130
Tests for hydrolysis of starch (dilute hydrochloric acid): 9.129
Test for hydrolysis of starch, iodine test, Fehling's solution: 16.10.1
Tests for hydrolysis of starch (salivary amylase): 9.130
Tests for, hydrolysis of sucrose, by dilute acids): 9.131
Tests for hydroxides: 12.11.5.11
Hydrolysis
Hydrolysis is the splitting of molecule using a reaction with water AB + H2O --> AH + BOH.
In the above equation, compound AB is decomposed and the hydrogen and hydroxyl group of water is attached to the separate chemical products, AH and BOH.

Hydroxides
Hydroxide , HO-, hydroxide ion, hydroxyl ion, hydroxide anion, an oxygen hydride, a conjugate base of a water.
An hydroxide is a compound of a metal with the hydroxide ion, OH-
Hydroxyl group -OH functional group (sodium hydroxide, Na⁺+ OH^-)
Hydroxyl ions
Alkalis and amphoteric oxides and hydroxides: 12.7.7
Alkalis with salts, hydroxides: 12.7.4
Decomposition of hydroxides: 3.30.3
Dilute acids with hydroxides, Mg(OH)2: 12.3.6
Dilute acids with hydroxides, NaOH: 12.3.7
Hydroxide (hydroxo), O-H-, monodentate ligand
Prepare hydroxides by precipitation: 12.1.33
Prepare hydroxides with ammonia solution: 3.33.2.1
Tests for ammonia, ammonium ions, "NH4OH": 12.11.3.11
Tests for hydroxides: 12.11.5.11
Tests for hydroxyl ions, ammonia solution: 13.6.5
Thermal decomposition of hydroxides: 3.30.3

Hydronium ion, H3O⁺
Hydronium ion, H3O⁺, hydroxonium ion, oxonium ion
Hydrogen bonds: 11.2.5
Hydronium ion (hydroxonium ion): 7.9.32
Hydronium ion, Acid-base reactions: 12.2.5.0
Hydronium ion, Oxides and Periodic Table: 12.17.1.1
Hydronium ion
An hydronium ion H3O⁺ is formed when acids dissociate in water IUPAC prefers "oxonium ion", i.e. an ion with a trivalent oxygen cation, and allows "hydroxonium ion", but "hydronium ion" seems to be the most popular way of referring to "H3O⁺".

Hydroxyapatite
Hydroxyapatite, Ca3(PO4)3OH, Ca10(PO4)6(OH)2, Ca5[OH(PO4)3, durapatite, mineral, occurs in “phosphate rock”, human bone and artificial skeletons
. It may be prepared from calcium nitrate and potassium dihydrogen phosphate and from other methods for pure forms.
.

Hydroxy compounds
Hydroxyapatite, (Geology)
Hydroxybenzaldehydes
4-Hydroxybenzaldehyde, C7H6O2, Gallic aldehyde, C7H6O4: Anisaldehyde
Protocatechuic aldehyde, C7H6O3, Syringaldehyde, C9H10O4: Vanillin
Hydroxybenzoic acids
Gallic acid 4-O-glucoside, C13H16O10, Gentisic acid, C7H6O4, Lambertianin C, C123H80O78, Protocatechuic acid, C7H6O4
Punicalagin, C48H28O30, Sanguiin H-6, C82H54O52: Syringic acid, C9H10O5
Valoneic acid dilactone, C21H10O13, Vanillic acid, C8H8O4
Hydroxybenzoketones
2,3-Dihydroxy-1-guaiacylpropanone, C10H12O5 | (3-Methoxyacetophenone), C9H10O2
Hydroxycinnamaldehydes
Ferulaldehyde, C10H10O3, Sinapaldehyde, C11H12O4
Hydroxycinnamic acids
| Caffeic acid | Chlorogenic acid
| Cichoric acid
| Cinnamic Acid
| Coumaric acid
| Ferulic acid
| Phaseolic acid
| Rosmarinic Acid
| Sinapinic acid
Hydroxycoumarins
| Coumarin | Eculetin | Esculin
Hydroxyphenylacetic acids
3,4-Dihydroxyphenylacetic acid, C8H8O4 | 4-Hydroxyphenylacetic acid, C8H8O3 | Homovanillic acid, C9H10O4
Homoveratric acid, C10H12O4 | Methoxyphenylacetic acid, C9H10O3
Hydroxyphenylpropenes
Acetyl eugenol, C12H14O3
Anethole, C10H12O, monoterpene
Estragole, C10H12O, methyl chavicol
Eugenol, C10H12O2
Gingerol, C17H32O4
Hydroxyphenylpropionic acids
Dihydrocaffeic acid, C9H10O4
Hydroxyphenylpropanoic acids
Dihydro-p-coumaric acid, C9H10O3 | Dihydrocaffeic acid, C9H10O4

Hydrozincite
Hydrozincite, Zn5(CO3)2(OH)6, Zn[(OH)3CO3], zinc bloom, basic zinc carbonate, white to yellow, tiny translucent crystals, fluoresces in UV light

Hypolaetin
Hypolaetin, hypoletin, (8-Hydroxyluteolin) 1655, C15H10O7, a pentahydroxyflavone, anti-inflammatory, cytoprotective
It occurs in common thyme, Italian corn salad Valerianella eriocarpa, and Hypolaena fastigiata.

Hygroscopic
Hygroscopic, deliquescent and efflorescent substances
3.0 Hygroscopic polymers
1.0 Hygroscopic substances
Deliquescent substances
2.0 Silica gel
Efflorescent substances
4.0 Expose different salts to the air
3.4.13.5 Storing hygroscopic and deliquescent substances
Hygroscopic substances absorb water from the air
The hygroscopic solids absorb water without liquefaction.
Hygroscopic substances absorb water from the air under some conditions of humidity and temperature.
Hygroscopic chemicals include the following:
| Anhydrous calcium chloride CaCl2 | Ethanol ("absolute alcohol", C2H5OH | Glycerol (glycerine, glycerin, CH2OH.CHOH.CH2OH | Iron (II) sulfate-7-water FeSO4.7H2O | Concentrated nitric acid HNO3 |
| Potassium carbonate K2CO3 | Potassium chloride KCl (slight) | Concentrated potassium hydroxide KOH | Potassium iodide KI (slight) | Silica gel desiccant SiO2 | Anhydrous sodium carbonate Na2CO3 |
| Concentrated sodium hydroxide NaOH | Sodium nitrite NaNO2 | Anhydrous sodium sulfate Na2SO4 | Concentrated sulfuric acid H2SO4 |
* Silica gel, SiO2
Dry silica gel SiO2, is hygroscopic.
It absorbs water from the air, but does not dissolve in the water.
It occurs naturally and is manufactured as beads to be used as a desiccant in laboratory glass vacuum desiccators and in silica gel packets packed with equipment, e.g. microscopes, food products and toilet products.
Be careful! The packets may usually bear a warnings not to eat the contents, so children should not have access to them, thinking they are packets of lollies!
* Hygroscopic polymers
"Fortune Teller Fish" (child's toy)
Hygroscopic polymers, including nylon, ABS, polycarbonate, cellulose, and Poly(methyl methacrylate)
Some forms of hygroscopic red cellophane used in novelties are flat on a warm dry surface, but curl up in the hand when they absorb sweat and evaporate moisture.
Experiments
Expose different salts to the air
Put equal volumes of different salts on separate watch glasses, e.g. dry calcium chloride, copper (II) sulfate-5-water, iron (II) sulfate-7-water, potassium carbonate, dry silica gel, pure sodium chloride, and sodium sulfate-10-water.
Examine the salts after one hour and after one day.
Expose sodium carbonate decahydrate to the air
The relative molecular mass of sodium carbonate-10-water = 286.15.
The relative molecular mass of anhydrous sodium carbonate = 105.99.
The relative molecular mass of sodium carbonate in sodium carbonate crystals = (105.99/286.15) X 100 = 37%.
Open an unopened packet of washing soda.
Put 10 g of washing soda in an evaporating basin.
Record the time for the crystals to change into a white powder.
Leave the basin for two days.
Record the time for all the crystals to change into a white powder.
Weigh the powder.
Calculate the weight of the powder expressed as the percentage of the original weight of the crystals.

Hypochlorite, ClO^-
Calcium hypochlorite, Ca(OCl)2: 18.7.2.2.1
Calcium hypochlorite, Ca(OCl)2: Calcium hypochlorite
Electrolysis of sodium chloride solution to prepare sodium hypochlorite: 15.5.12.6
Hypochlorites, hazards: 3.7.7
Inorganic hypochlorites: 18.7.2.2
Pass chlorine through water: 12.4.9
Prepare chlorine: 12.4.1.0
Prepare chlorine water: 12.4.2
Prepare sodium hypochlorite: 12.1.13
Sodium hypochlorite
Sodium hypochlorite decomposition, cobalt sulfate catalyst: 17.3.14
Swimming pools, checklist: 3.9.2

19.4.1Household chemicals checklist
Abrasives, carbides
Acetic acid, vinegar
Acetone, nail polish remover
Albumen, egg white
Alcohol, ethanol
Adhesives, list of adhesives, glue
Algicide, control of algae in swimming pool
Ammonia, ammonia solution, "cloudy ammonia"
Alums, potassium alum
Aluminium, beverage can, aluminium foil
Ammonium carbonate, smelling salts
Ammonium chloride, solder flux
Ammonium sulfate, fertilizer
Antifreeze, ethylene glycol, ethane-1,2-diol
Aspirin, ASA
Baking powder, leavening agent
Baking soda, bicarb
Bakelite, plastic
Bean curd, tofu
Bitumen, asphalt
Bleach, Ca hypochlorite
35.13.3.1 Borax, (Geology)
Boric acid, Boracic acid
Calcium carbonate, egg shell
Ca hydroxide, limewater
Ca hypochlorite, bleaching powder
Calcium oxide, garden lime, quicklime
Calcium sulfate, school chalk
Candles, wax candles
Carbonated beverages
3.34, Carbon dioxide
Carbon tetrachloride, dry cleaning fluid
Cement
18.2.0, Chlorine used in swimming pools
Chromium, plating
Citric acid, lemon juice
Clay, soil mineral, (Geology)
Cooking oils
Copper, wire
Corn flour
Copper (II) sulfate, bluestone
Bordeaux mixture, fungicide
Cream of tartar
Creosote
Cyanoacrylate, glue
Detergents
Dry cells, torch battery
Dyes
Fruit salts
Emulsions, face cream
Fat, lipids
Formic acid, ant poison
Gas-Pak, gas
Gelatine, jelly
Glass, window
Glucose, jellybean
Gluten, bread
Hydrogen peroxide, "peroxide"
Ice, ice lolly
Ink, fingerprints
Iodine, tincture of iodine
Iron, nails
Kerosene, paraffin oil
Lead, fishing sinker
Lemon juice, citric acid
Lime, garden lime
Linseed oil
Magnesium hydroxide, magnesia
Magnesium sulfate, Epsom salts, medicine
Methylated spirits, "metho"
Milk, ice cream
Oil, lubricating oil
Oils
Petrol, gasoline, gas, (Geology)
Petrolatum, "Vaseline"
Paraffin
Polymers and plastics, ball point pen
Potassium permanganate, Condys crystals
Putty, window putty
PVAC glue
Red Lead, paint
Rusting
Silica, quartz
Silicones
Soap
Sodium bicarbonate, "carb soda"
Sodium carbonate, washing soda
Sodium chloride, table salt
Sodium hydroxide, caustic soda
Sodium metabisulfite, sterilizer
Sodium silicate
Solders, flux
Starch
Sucrose, sugar
Sulfur
Talc, tailor's chalk, (Geology)
Tin, tin can
Turpentine, turps
Urea, fertilizer
Water, (Chemistry)
Water, (Physics)
Water glass
Yeast, bread
Zinc. zinc- carbon battery casing

Hydroxyglucobrassicin Hydroxyglucobrassicin, , C16H20N2O10S2^-, (4-Hydroxyglucobrassicin), indolylmethylglucosinolic acid, indolyl carbohydrate,
It occurs in rapeseed Brassica napus var. midas, and in other Brassica species if mechanical damage or insect damage

Hydroxykynurenic acid
Hydroxykynurenic acid, C10H7NO4, (6-Hydroxykynurenic acid), amino acid, quinoline, in fats and oils
It occurs in ginkgo, Ginkgo biloba.

Hydrozincite
Hydrozincite, Zn5(CO3)2(OH)6, Zn[(OH)3CO3], zinc bloom, basic zinc carbonate, white to yellow, tiny translucent crystals, fluoresces in UV light

Hyperin
Hyperoside, C21H20O12, hyperoside, Quercetin 3-galactoside, flavonol O-glycoside, phenolic compound, antibacterial
It occurs in St John's wort, (Hypericum perforatum), Cuscuta chinensis, Camptotheca acuminata, Carpobrotus edulis, Drosera, Prunella, Rumex, Stachys

34.7 Heat treatment of metals
Heating steel material to "red heat" then cooling it slowly is called annealing.
Putting steel material heated to red heat into cold liquid to cool it quickly is called quenching.
Reheated steel material is quenched to the temperature slightly lower than "red heat" temperature, then cooled slowly, called tempering.
Annealing, quenching and tempering are heat treatings to change rigidity, brittleness and toughness, by changing the arrangement of iron atoms.
Annealing is a form of heat treatment to soften a metal and make it easier to work.
Annealing is often used to soften steel to relax its inner stress to change its shape by forging, pressing and machining.
Experiment
34.7.1 Annealing
34.7.2 Heat treatment of needles
34.7.3 Heat treatment of razor blades or steel knitting needles
34.7.4. Heat treatment of steel needles, annealing, quenching, tempering
34.7.5 Quenching
34.7.6 Tempering

Scopolamine, (C17H21NO4), Tropane Alkaloid
Scopolamine, hyoscine, Hyoscine, Skopolamin, Oscine, syrup, narcotic ("truth drug"), "Devil's breath",sedative
Scopolamine less toxic than Hyoscyamine, used for anaesthetic premedication, treat urinary incontinence, motion sickness, antispasmodic, anticholinergic, anti-emetic and antivertigo properties, used control the secretion of saliva and gastric acid, to slow gut motility, mild nausea, motion sickness and prevent vomiting
It occurs in in Atropa belladonna, in Datura ferox, in Duboisia myoporoidesi, Duboisia leichhardtii.
See diagram: Scopolamine.
(-)-Scopolamine hydrobromide trihydrate, (C17H21NO4.HBr.3H2O), hyoscine hypobromide

Securinine, (C13H15NO2), Unclassified Alkaloid
Securinine, Securinin, occurs in Securinega, in Phyllanthus, indolizine alkaloid.
See diagram: Securinine.