Concise Glossary Of Safety Engineering

Concise Glossary Of Safety Engineering:

Sr.No	Name	Meaning
1	Absolute humidity	The amount of water vapour present in the atmosphere, defined in terms of number of kilograms (or grams) of water in one cubic metre of air. The relative humidity is usually expressed as a percentage, the ratio of the pressure of the water vapour actually present in the atmosphere to the pressure of the vapour that would be present if the vapour was saturated at the same temperature.
2	Activated	Carbon Charcoal treated to remove hydrocarbons and to increase its powers of absorption. Used in many processes for recovering valuable materials out of gaseous mixtures, as a deodorant, and in & as masks.
3	Acute Effect	Immediate effect (Acid burn, Ammonia or Chlorine inhalation) .
4	Addition compound	A chemical compound formed by the addition of an atom to a; molecule, e.g. phosgene Co+Cl2 = CoCl2.
5	Acid	A compound which yields hydrogen ions in solution.
6	Activity	Ease of undergoing chemical change.
7	Alloy	Metallic solid resulting from dissolving two or more molten metals in each other, possessing properties different from any of its constituents.
8	Amalgam	An alloy of a metal and mercury.
9	Analysis	The determination of the composition of a substance; the decomposition of a substance.
10	Atom	The smallest quantity of an element that enters into chemical combination. It has a very small, dense nucleus, positively charged. Negative particles called electrons rotate around the nucleus.
11	Aero metal	A casting alloy of AI, Zn and Cu.
12	Affinity	Chemical attraction, the force binding atoms together.
13	Alkali	A soluble hydroxide of a metal, particularly the alkali metal. Alkali metals-univalent metals lithium, sodium, potassium, rubidium, and caesium (Group IA of the periodic table). Alkaline earth metals bivalent metals beryllium, magnesium, calcium, strontium, barium and radium (Group 2A of the table).
14	Alcoholates	Metallic salts of alcohol, formed by replacement of hydrogen atoms in, the hydroxyl groups of the latter by metals e.g. sodium ethanolate C2H5ONa.
15	Alcohol	A class of organic compounds derived from the hydrocarbons, one or more hydrogen atoms in molecules of the latter being replaced by hydroxyl groups - e.g. ethanol C2H5OH .
16	Aldehydes	A class of organic compounds of the type R.CO.H where R is an alkyl or aryl radical.
17	Alicylic compound	A type of organic compound that is essentially aliphatic, although it, contains a saturated ring of carbon atoms.
18	Aliphatic compounds	Organic compounds containing open chains of carbon atoms, in contradistinction to the closed rings of carbon atoms of the aromatic compounds.
19	Aromatic compounds	The original concept of aromatic compounds as derivatives of benzene has been extended to certain other organic compounds.
20	Alkaloids	A group of basic organic substances of plant origin, containing at least one nitrogen atom in a ring structure in the molecule. Many have important physiological actions and are used in medicine, e.g. codeine, cocaine, nicotine, quinine, morphine.
21	Alkanes	A homologous series of saturated' hydrocarbons having the general formula Cn2n+2. They are chemically inert, stable and inflammable. The first four members of the series (methane, ethane, propane, butane) are gases at ordinary temperatures, the next eleven are liquids and form the main constituents of paraffin oil, the higher members are solids.
22	Alkenes Olefins,	A homologous series of unsaturated hydrocarbons having .the general formula CnH2n.
23	Alkynes	A homologous series of unsaturated hydrocarbons having the general formula CnH2n-2 and containing a triple bond between two of the carbon atoms in the molecule, e.g. acetylene.
24	Aklylarene	An arene (e.g. benzene) with one or more hydrogen atoms in the I molecule replaced by alkyl groups, e.g. ethylbenzene.
25	Amides	A group of organic compounds formed by replacing hydrogen atoms of ammonia NH3 by radicals, e.g. acetamide CH3CONH2. The general formula is RCONH2 where CONH2 is the amide group.
26	Amines	Compounds formed by replacing hydrogen atoms of ammonia NH3 by organic radicals. Classified into primary amines of the type NH2R1 secondary NHR2 and tertiary NR3.
27	Amorphous	Non-crystalline, having no definite ;form or shape.
28	Amphoteric	Chemically reacting as acidic for strong bases and as basic towards strong acids, e.g. amphoteric oxide, zinc oxide, gives rise to zinc salts of strong acids and zincates of the alkali metals.
29	Anhydride	The anhydride of a substance is that which when chemically combined with water, gives that substances. A basic anhydride is the oxide of a metal and forms a base with water (Na2O+H2O = 2NaOH), and acidic anhydride is the oxide of a nonmetal and forms an acid with water (SO2+H2O)=H2SO4).
30	Anhydrite	A naturally occurring form of calcium sulphate .
31	Anhydrous	Without water, often applied to salts without water of crystallization.
32	Base metals	In contradistinction to the noble metals, metals that corrode, tarnish or oxidise on exposure to air, moisture or heat.
33	Binary compound	A chemical compound of two elements only. Denoted by the suffix- ide, e.g. calcium carbide CaC2.
34	Base	The hydroxide of a metal. An alkali.
35	Boiling	Point The temperature at which the pressure of the vapour of a substance equal that of its surrounding, atmosphere.
36	Boiling	Ebullition. The state of a liquid at its boiling point when the maximum vapour pressure of the liquid is equal to the external pressure to which the liquid is subject, and .the liquid is freely converted into vapour. Boiling point is the temperature at which the liquid boils freely under standard atmospheric pressure i.e. 760 mm of Hg.
37	Carbocyclic	Compounds A class of organic compounds containing closed rings of carbon atoms in their molecules. It includes alicyclic (e.g. cyclohexane) and aromatic (e.. benzene) compounds.
38	Carbohydrates	A large group of organic compounds composed of carbon, hydrogen and oxygen only with general formula Cx ( H2O)y.
39	Carcinogen	A substance capable of producing cancer (carcinoma).
40	Caustic	Corrosive towards organic matter (but not applied to acids), e.g. caustic soda, caustic alkali-sodium or potassium hydroxide, caustic potash - KOH, caustic soda - NaOH.
41	Celluloid	A thermoplastic material made from cellulose nitrate and camphor.
42	Cellulose	A polysaccharide that occurs widely in nature in fibrous form as the structural tissue in the cell walls of plants.
43	Chemical change	A change m a substance involving an alteration in its chemical composition, due to an increase, decrease or rearrangement of atoms within its molecules.
44	Chemical energy	That part of the energy stored within an atom or molecule that can be released by a chemical reaction.
45	Chloracne	A disfiguring skin disease that is caused by certain chlorinated aromatic hydrocarbons. It can result from contact, ingestion or inhalation of the chemicals.
46	Chromophore	Any chemical group, such as the azo group, that causes a compound to have a distinctive colour.
47	Chronic	Effect Effect after prolonged exposure (poisoning due to lead, chromium, j mercury etc.)
48	Coalgas	Fuel gas manufactured by the destructive distillation of coal in closed iron retorts, often' supplemented with watergas or natural gas. Coal-tar is a thick black oily liquid obtained as a by-product of coal- gas manufacture. Coke is a greyish porous brittle solid i containing @ 80% carbon. Obtained 'as a residue in the manufacture of coal-gas (gas-coke), also made specially in coke ovens, in which the coal is treated at lower temperatures ;than in pas manufacture.
49	Corrosive	Liquids Acid, Alkalis, Ammonia liquor, iCarbamate solution, caustic solution, amines etc.
50	Critical pressure,	Critical pressure is the pressure of the saturated vapour of a substance temperature and volume at the critical temperature, above ; which a gas cannot be liquefied by pressure alone. Critical volume is 'the volume occupied by unit mass of a substance at its critical; temperature and critical pressure.
51	Critical Velocity	The velocity at which the flow of a liquid ceases to be streamlined and becomes turbulent.
52	Crystals	A solid in which the particles (molecules, atoms, ions) are arranged in a definite patter in space.
53	Cryostat	A vessel in which a specified low temperature may be maintained.
54	Culture medium	A preparation used for growing and cultivating micro-organisms for experimental purposes.
55	Deliquescent	Having the property of picking up moisture from the air to such an extent as to dissolve in it, becoming liquid on exposure to air.
56	Density	The mass of unit volume of a substance, e.g. kg/m3 .
57	Derivative	A compound derived from (but not necessarily prepared from) some other compound, usually retaining the general structure of the parent compound, e.g. nitrobenzene C6H5NO3 is a derivative of benzene C6H6, one hydrogen atom in the molecule of the latter being replaced by a nitro group.
58	Detergents	Cleaning agents, products used in solution for washing or cleaning by action other than simple dissolution, usually with the aid of surface- active agents. Unlike soaps, they are effective in hard water and do not form a scum.
59	Decomposition	The process of breaking down a substance into a simpler one.
60	Deliquescence	The absorption of water from the air by a substance to the extent that the substance is dissolved in the absorbed water.
61	Desiccant	Drying agent absorbs moisture from its surroundings.
62	Distillate	The condensed liquid obtained by a distilling process.
63	Diazo	Compounds Like azo compounds, diazo compounds contain two adjacent nitrogen atoms which may form and azo group, but only one is attached I to a carbon atom e.g. diazomethane CH2=N
64	Diazonium	Compounds Organic compounds of the general formula RN2X, where R is an aryl radical, RN2 is a cation and X is an anion.
65	Dihydric	Containing two hydroxyl groups in a molecule, e.g. a diol.
66	Dyes	Coloured substances that can be fixed firmly to a material to be dyed so as to be more or less fast to water, light and soap. Types - acid Idyes, azo dyes, direct dyes, mordents, vat dyes.
67	Electrode	The plate or terminal of an electric system.
68	Electrolyte	A substance which will conduct a current when melted, or in solution. A substance decomposable by an electric current.
69	Electron	A constituent of an atom possessing a unit negative electrical charge and having negligible mass from a chemical point of view.
70	Element	The simplest form of matter.
71	Energy	The ability to do work. All changes involve loss or gain of energy.
72	Equation	A concise statement of a chemical reaction using the symbols and formula of the reactants and products.
73	Equilibrium	Condition in which two processes proceed simultaneously in opposite Directions at the same rate.
74	Emulsion	A two-phase system in which the disperse phase consists of minute droplets of liquid .
75	Enthalpy	Heat content H. A thermodynamic property of a substance given by H, == U+pV, where U is the internal energy, p the pressure, and V the volume.
76	Entropy	S. A quantity introduced in the first i place to facilitate the calculations and to give clear expression to the! results of thermodynamics.
77	Enzyme	A large group of proteins produced by living cells, which act as catalysts in the chemical reactions upon which life depends.
78	Ergonomics	The engineering aspects of the study .of the relation between human workers and their working environment.
79	Esters	Organic compound's corresponding to inorganic salts, derived by replacing hydrogen of an acid by an organic radical or group e.g. ethyl acetate CH3COOC2H5 is the ethyl ester of acetic acid CH2COOH.
80	Ethers	A group of organic compounds with the general formula R-O-R' formed by the condensation of two alcohol molecules.
81	Explosion	A violent and rapid increase of pressure in a confined space. It may be caused by an external source of; energy (heat) or by an internal exothermic reaction in which: relatively large volumes of gases areproduced.
82	Explosives	Substances that undergo a rapid chemical change with production of gas on being, heated or struck .
83	Fatigue of Metals	The deterioration of metals owing to repeated stresses above a certain critical value, it is accompanied by changes in the crystalline structure of the metal.
84	Filtrate	The liquid obtained after filtration.
85	Flux	Material which permits another substance to melt more easily.
86	Formula	The composition of a substance indicated by symbols of each element present and subscript numbers showing the number of each type of atom involved.
87	Freezing	Point Temperature at which a liquid changes to a solid.
88	Fertilisers	Materials put into 'the soil to; provide compounds of elements essential to plant life more I particularly nitrogen, phosphorus and potassium.
89	Fire	A chemical reaction accompanied by the evolution of heat, light and flame (i.e. a glowing mass of gas). It is generally applied to the chemical combination with oxygen 'of carbon and other elements' constituting the substance being burnt.
90	Flammable	Substances with flash point < 80 °FJ i Those having P.P. > 80 °F are called' combustibles. Flash Point The lowest temperature at which a I substance gives off sufficient inflammable vapour to produce a momentary flash when a small flame is applied.
91	Flue	Gas The gaseous products of combustion from a boiler furnace consisting predo-minantly of CO2, CO, O2, N2 and steam. Analysis of the flue ~ gases is used to check the efficiency of the furnace.
92	Fluid	A substance that takes the shape of the shape of the vessel containing it, a liquid or gas.
93	Fuel	A substance used for producing heat energy, either by means or the release of its chemical energy by combustion or its nuclear energy by nuclear fission.
94	Fungicide	A substance capable of destroying I harmful fungi, such as moulds and mildews.
95	Gas	A substance whose physical state (the gaseous state) is such that it always occupies the whole of the ; space in which it is contained.
96	Gas	Mask Respirator a device for protecting the face and breathing organs against poisonous gases. Germicide A substance capable of destroying bacteria.
97	Halide	A binary compound of one of the halogen elements (fluorine, chlorine, bromine or iodine), a salt of the hydride of one of these elements.
99	Heat	Energy possessed by a substance in the form of kinetic energy of atomic or molecular translation, rotation or vibration. The heat contained by a body is the product of its mass, temperature and specific heat capacity. It is expressed in joules, calories or B.Th. U. Heat is transmitted by conduction,; convection and radiation. Its physical effects are rise in temperature, change of state from solid to liquid (melting), solid to gas (sublimation), liquid to gas (evaporation), boiling, expansion and electrical effects.
100	Heat exchanger	Any device that transfers heat from one. fluid to another without allowing the fluids to come into contact with each other.
101	Heat of reaction	The quantity of heat given out (exothermic) or absorbed in (endothermic) a chemical reaction usually per mole of reacting substances.
102	Herbicides	Substances that kill plants or inhibit their growth. Selective herbicides affect only particular plant types, making it possible to attack weed growing among cultivated plants.
103	Heterocyclic compounds	Organic compounds containing e compounds ring structure of atoms in the molecule, the ring including atoms of elements other than carbon e.g. C5H5N.
104	Homocyclic compounds	Organic compounds the molecules compounds of which contain a ring structure of atoms of the same kind (usually carbon), e.g. benzene C6H6.
105	Homologous	Series A series of chemical compounds of uniform chemical type, showing a regular gradation in physical [properties and represented by a general molecular formula, the! molecule of each member of the series differing from the preceding one by a definite constant group of atoms, e.g. the alkanes. Members of the same homologous series are called homologous, e.g. methane CH4, and ethane C2H6.
106	Hydrocarbons	Organic compounds that contain only carbon and hydrogen. They are classified as either aliphatic or aromatic compounds (or a combination of both). Hydrocarbons may be either saturated or unsaturated compounds.
107	Imide	Imido compound , a compound derived from ammonia, containing the imido group. NH, in which the two hydrogen atoms of ammonia are replaced by non acidic organic radicals.
108	Inert or noble gases	Rare gases, helium, neon, argon, gases krypton, xenon, radon. They are all chemically inactive, though some compounds have been reported.
109	Ion	An atom which has acquired an electrical charge as a result of the gain or loss of electrons; a charged atom or radical.
110	Isotopes	Atoms of an element having the same chemical properties but differing in mass number are different isotopes of the element.
111	Insecticide	A substance used for killing insect pests.
112	Isomerism	The existence of two or more chemical compounds with the same molecular formula but having different properties owing to a different arrangement of atoms within the molecule, e.g. ammonium cyanate NH4CNO and urea CO (NH2)2 are isomers.
113	Latent heat	The quantity of heat absorbed or released in an isothermal transformation of phase.
114	Liquid	A state of matter intermediate between a solid and a gas, in which the molecules are relatively free to move with respect to each other but are restricted by cohesive I forces to the extent that the liquid maintains a fixed volume. Liquids assume the shape of the vessel containing them, but are only slightly compressible.
115	Local effect	Effect confined to affected part (chemical burn, dermatitis) .
116	Malleability	The ability to be hammered out into thin sheets.
117	Matter	A specialised form of energy that has the attributes of mass and extension in space and time.
118	Melting point	The constant temperature at which the solid and liquid phase of a substance are in equilibrium at a given pressure. Melting points are normally quoted for standard atmospheric pressure.
119	Metalv	Element which readily loses electrons to form positive ions; conductor of electricity.
120	Metalloid	Element possessing characteristics of both metals and non-metals .
121	Mixture	A combination of substances held together by physical rather than by chemical means.
123	Molecule	Smallest particle of a compound capable of having the properties of the compound.
124	Monomer	A chemical compound consisting of single molecules, as opposed to a polymer, the molecules of which are built up by the repeated union of monomer molecules.
125	Noble metals	Metals such as silver, gold and platinum, that do not corrode or tarnish in air or water and are not easily attacked by acids.
126	Non-metal	Element which readily gains electrons to form negative ions; nonconductor of electricity.
127	Pesticides	Substances that kill pests. They include insecticides.
128	pH.	Logarithm of the reciprocal of the I molar concentration of the hydrogen ion; a scale indicating the acidity of a solution; if pH is less than 7 solution is acidic, if pH is 7 solution, is neutral, if pH is greater than 7 solution is alkaline.
129	Physical change	An alteration of the properties of a substance without affecting the substance itself.
130	Precipitate	A solid which forms in and settles out from a solution.
131	Products	The substances formed as a result of a chemical change.
132	Petrochemicals	Chemical substances derived from petroleum (or natural gas).
133	Petroleum	Mineral oil. A natural mixture of hydrocarbons and other organic compounds. Fractional disti-llation yields petrol, paraffin oil, lubricating oil, petrolatum and paraffin wax.
134	Plasticizer	(1) A non-volatile liquid added to I paints and varnishes to prevent brittleness of the dried film. (2) A liquid or solid substance added to synthetic or natural resins to modify their flow properties.
135	Polymerisation	The chemical union of two or more molecules of the same compound to form larger molecules, resulting in the formation of a new compound of the same imperial formula but of greater molecular weight, e.g. Paraldehyde (CH,CHO), is formed by the polymerisation of acetaldehyde CH,CHO monomer. It includes addition polymerisation, condensation polymerisation and copolymerisation. Many important products such as plastics and textile fibres consist of polymeric substance, either natural (e.g. cellulose) or synthetic (e.g. nylon).
136	Pressure	The force per unit area acting on a surface. Absolute pressure is the pressure measured with respect to zero pressure. Gauge pressure is the pressure measured by a gauge in excess of the pressure of atmosphere.
137	Radical	A group of elements bonded together which behave chemically as a single atom.
138	Radioactivity	The breakdown of the nucleus of an atom through the emission of alpha, beta and gamma rays.
139	Reducing agent	A substance that removes oxygen from, or adds hydrogen to, another substance.
140	Refrigerant	A fluid used in the refrigerating cycle of a refrigerator, usually of a liquid that will vaporise at a low temperature, e.g. freon or ammonia.
141	Relative density	Specific gravity. The ratio of the density of solid or liquid at a specified temperature (often 20°C) to the density of water at the temperature of its maximum density (4oC).
142	Salt	Compound which ionises, but which produces neither hydrogen nor hydroxide ions in solution.
145	Solubility	The extent to which a solute can dissolve in a solvent; the concentration of a saturated solution of a given solute.
146	Solution	Homogeneous, non-setting mixture of two ingredients, solute and solvent.
147	Solvent	The medium in which a substance is dissolved.
148	Stable	Relatively inert; hard to decompose.
149	Synthesis	The formation of a compound by combining elements or more simple compounds.
150	Skin Poisons	Cause dermatitis and ulcer to skin (Chromates, Naphtha, Amines, Aniline etc.,)
151	Soda	Washing soda Na2CO3, backing soda, NaHCO3, caustic soda NaOH.
152	Soda ash	The common name for anhydrous Na2CO3.
153	Soda lime	A solid mixture of NaOH and Ca(OH)2
154	Specific heat capacity	Specific heat capacity divided by mass. The quantity of heat required to raise the temperature of unit mass of a substance by one degree.
155	Systemic effect	Effect on one complete or more than one systems, (exposure to CO, H2S, Benzene, Aniline, Methanol etc.)
156	Temperature	Temperature is a measure of hotness of a body. It can be defined as a property determining the rate at which heat will be transferred to or from it. Temperature is thus a measure of the kinetic energy of the molecules, atoms or ions of which matter is composed.
157	Thermo-dynamics	The study of the general laws governing processes that involve heat changes and the conservation of energy.
158	Toxic	Poisonous, toxicology - the study of poison, toxin-poison.
159	Toxic dusts	Dust of asbestos, silica, coal, cotton, iron, lead, sugarcane hay can cause lung diseases.
160	Toxicity	Ability of a chemical to cause internal or external injury on human body.
161	Vapour	A substance in the gaseous state that can be liquefied by increasing the pressure without altering the temperature. A gas below its critical. temperature.
162	Vapour density	A measure of the density of a gas or vapour, usually, given relative to Oxygen or hydrogen or air.
163	Vermicide	A substance used to kill worms.
164	Viscosity	The property of a fluid whereby it tends to resist relative motion within itself.
165	Volatile	Forms a gas with case.
156	Water gas	A fuel gas obtained by the action of steam on glowing hot coke. It consists of CO and H.

Sr.No

Name

Meaning

Absolute humidity

The amount of water vapour present in the atmosphere, defined in terms of number of kilograms (or grams) of water in one cubic metre of air. The relative humidity is usually expressed as a percentage, the ratio of the pressure of the water vapour actually present in the atmosphere to the pressure of the vapour that would be present if the vapour was saturated at the same temperature.

Activated

Carbon Charcoal treated to remove hydrocarbons and to increase its powers of absorption. Used in many processes for recovering valuable materials out of gaseous mixtures, as a deodorant, and in & as masks.

Acute Effect

Immediate effect (Acid burn, Ammonia or Chlorine inhalation) .

Addition compound

A chemical compound formed by the addition of an atom to a; molecule, e.g. phosgene Co+Cl2 = CoCl2.

Acid

A compound which yields hydrogen ions in solution.

Activity

Ease of undergoing chemical change.

Alloy

Metallic solid resulting from dissolving two or more molten metals in each other, possessing properties different from any of its constituents.

Amalgam

An alloy of a metal and mercury.

Analysis

The determination of the composition of a substance; the decomposition of a substance.

Atom

The smallest quantity of an element that enters into chemical combination. It has a very small, dense nucleus, positively charged. Negative particles called electrons rotate around the nucleus.

Aero metal

A casting alloy of AI, Zn and Cu.

Affinity

Chemical attraction, the force binding atoms together.

Alkali

A soluble hydroxide of a metal, particularly the alkali metal. Alkali metals-univalent metals lithium, sodium, potassium, rubidium, and caesium (Group IA of the periodic table). Alkaline earth metals bivalent metals beryllium, magnesium, calcium, strontium, barium and radium (Group 2A of the table).

Alcoholates

Metallic salts of alcohol, formed by replacement of hydrogen atoms in, the hydroxyl groups of the latter by metals e.g. sodium ethanolate C2H5ONa.

Alcohol

A class of organic compounds derived from the hydrocarbons, one or more hydrogen atoms in molecules of the latter being replaced by hydroxyl groups - e.g. ethanol C2H5OH .

Aldehydes

A class of organic compounds of the type R.CO.H where R is an alkyl or aryl radical.

Alicylic compound

A type of organic compound that is essentially aliphatic, although it, contains a saturated ring of carbon atoms.

Aliphatic compounds

Organic compounds containing open chains of carbon atoms, in contradistinction to the closed rings of carbon atoms of the aromatic compounds.

Aromatic compounds

The original concept of aromatic compounds as derivatives of benzene has been extended to certain other organic compounds.

Alkaloids

A group of basic organic substances of plant origin, containing at least one nitrogen atom in a ring structure in the molecule. Many have important physiological actions and are used in medicine, e.g. codeine, cocaine, nicotine, quinine, morphine.

Alkanes

A homologous series of saturated' hydrocarbons having the general formula Cn2n+2. They are chemically inert, stable and inflammable. The first four members of the series (methane, ethane, propane, butane) are gases at ordinary temperatures, the next eleven are liquids and form the main constituents of paraffin oil, the higher members are solids.

Alkenes Olefins,

A homologous series of unsaturated hydrocarbons having .the general formula CnH2n.

Alkynes

A homologous series of unsaturated hydrocarbons having the general formula CnH2n-2 and containing a triple bond between two of the carbon atoms in the molecule, e.g. acetylene.

Aklylarene

An arene (e.g. benzene) with one or more hydrogen atoms in the I molecule replaced by alkyl groups, e.g. ethylbenzene.

Amides

A group of organic compounds formed by replacing hydrogen atoms of ammonia NH3 by radicals, e.g. acetamide CH3CONH2. The general formula is RCONH2 where CONH2 is the amide group.

Amines

Compounds formed by replacing hydrogen atoms of ammonia NH3 by organic radicals. Classified into primary amines of the type NH2R1 secondary NHR2 and tertiary NR3.

Amorphous

Non-crystalline, having no definite ;form or shape.

Amphoteric

Chemically reacting as acidic for strong bases and as basic towards strong acids, e.g. amphoteric oxide, zinc oxide, gives rise to zinc salts of strong acids and zincates of the alkali metals.

Anhydride

The anhydride of a substance is that which when chemically combined with water, gives that substances. A basic anhydride is the oxide of a metal and forms a base with water (Na2O+H2O = 2NaOH), and acidic anhydride is the oxide of a nonmetal and forms an acid with water (SO2+H2O)=H2SO4).

Anhydrite

A naturally occurring form of calcium sulphate .

Anhydrous

Without water, often applied to salts without water of crystallization.

Base metals

In contradistinction to the noble metals, metals that corrode, tarnish or oxidise on exposure to air, moisture or heat.

Binary compound

A chemical compound of two elements only. Denoted by the suffix- ide, e.g. calcium carbide CaC2.

Base

The hydroxide of a metal. An alkali.

Boiling

Point The temperature at which the pressure of the vapour of a substance equal that of its surrounding, atmosphere.

Boiling

Ebullition. The state of a liquid at its boiling point when the maximum vapour pressure of the liquid is equal to the external pressure to which the liquid is subject, and .the liquid is freely converted into vapour. Boiling point is the temperature at which the liquid boils freely under standard atmospheric pressure i.e. 760 mm of Hg.

Carbocyclic

Compounds A class of organic compounds containing closed rings of carbon atoms in their molecules. It includes alicyclic (e.g. cyclohexane) and aromatic (e.. benzene) compounds.

Carbohydrates

A large group of organic compounds composed of carbon, hydrogen and oxygen only with general formula Cx ( H2O)y.

Carcinogen

A substance capable of producing cancer (carcinoma).

Caustic

Corrosive towards organic matter (but not applied to acids), e.g. caustic soda, caustic alkali-sodium or potassium hydroxide, caustic potash - KOH, caustic soda - NaOH.

Celluloid

A thermoplastic material made from cellulose nitrate and camphor.

Cellulose

A polysaccharide that occurs widely in nature in fibrous form as the structural tissue in the cell walls of plants.

Chemical change

A change m a substance involving an alteration in its chemical composition, due to an increase, decrease or rearrangement of atoms within its molecules.

Chemical energy

That part of the energy stored within an atom or molecule that can be released by a chemical reaction.

Chloracne

A disfiguring skin disease that is caused by certain chlorinated aromatic hydrocarbons. It can result from contact, ingestion or inhalation of the chemicals.

Chromophore

Any chemical group, such as the azo group, that causes a compound to have a distinctive colour.

Chronic

Effect Effect after prolonged exposure (poisoning due to lead, chromium, j mercury etc.)

Coalgas

Fuel gas manufactured by the destructive distillation of coal in closed iron retorts, often' supplemented with watergas or natural gas. Coal-tar is a thick black oily liquid obtained as a by-product of coal- gas manufacture. Coke is a greyish porous brittle solid i containing @ 80% carbon. Obtained 'as a residue in the manufacture of coal-gas (gas-coke), also made specially in coke ovens, in which the coal is treated at lower temperatures ;than in pas manufacture.

Corrosive

Liquids Acid, Alkalis, Ammonia liquor, iCarbamate solution, caustic solution, amines etc.

Critical pressure,

Critical pressure is the pressure of the saturated vapour of a substance temperature and volume at the critical temperature, above ; which a gas cannot be liquefied by pressure alone. Critical volume is 'the volume occupied by unit mass of a substance at its critical; temperature and critical pressure.

Critical Velocity

The velocity at which the flow of a liquid ceases to be streamlined and becomes turbulent.

Crystals

A solid in which the particles (molecules, atoms, ions) are arranged in a definite patter in space.

Cryostat

A vessel in which a specified low temperature may be maintained.

Culture medium

A preparation used for growing and cultivating micro-organisms for experimental purposes.

Deliquescent

Having the property of picking up moisture from the air to such an extent as to dissolve in it, becoming liquid on exposure to air.

Density

The mass of unit volume of a substance, e.g. kg/m3 .

Derivative

A compound derived from (but not necessarily prepared from) some other compound, usually retaining the general structure of the parent compound, e.g. nitrobenzene C6H5NO3 is a derivative of benzene C6H6, one hydrogen atom in the molecule of the latter being replaced by a nitro group.

Detergents

Cleaning agents, products used in solution for washing or cleaning by action other than simple dissolution, usually with the aid of surface- active agents. Unlike soaps, they are effective in hard water and do not form a scum.

Decomposition

The process of breaking down a substance into a simpler one.

Deliquescence

The absorption of water from the air by a substance to the extent that the substance is dissolved in the absorbed water.

Desiccant

Drying agent absorbs moisture from its surroundings.

Distillate

The condensed liquid obtained by a distilling process.

Diazo

Compounds Like azo compounds, diazo compounds contain two adjacent nitrogen atoms which may form and azo group, but only one is attached I to a carbon atom e.g. diazomethane CH2=N

Diazonium

Compounds Organic compounds of the general formula RN2X, where R is an aryl radical, RN2 is a cation and X is an anion.

Dihydric

Containing two hydroxyl groups in a molecule, e.g. a diol.

Dyes

Coloured substances that can be fixed firmly to a material to be dyed so as to be more or less fast to water, light and soap. Types - acid Idyes, azo dyes, direct dyes, mordents, vat dyes.

Electrode

The plate or terminal of an electric system.

Electrolyte

A substance which will conduct a current when melted, or in solution. A substance decomposable by an electric current.

Electron

A constituent of an atom possessing a unit negative electrical charge and having negligible mass from a chemical point of view.

Element

The simplest form of matter.

Energy

The ability to do work. All changes involve loss or gain of energy.

Equation

A concise statement of a chemical reaction using the symbols and formula of the reactants and products.

Equilibrium

Condition in which two processes proceed simultaneously in opposite Directions at the same rate.

Emulsion

A two-phase system in which the disperse phase consists of minute droplets of liquid .

Enthalpy

Heat content H. A thermodynamic property of a substance given by H, == U+pV, where U is the internal energy, p the pressure, and V the volume.

Entropy

S. A quantity introduced in the first i place to facilitate the calculations and to give clear expression to the! results of thermodynamics.

Enzyme

A large group of proteins produced by living cells, which act as catalysts in the chemical reactions upon which life depends.

Ergonomics

The engineering aspects of the study .of the relation between human workers and their working environment.

Esters

Organic compound's corresponding to inorganic salts, derived by replacing hydrogen of an acid by an organic radical or group e.g. ethyl acetate CH3COOC2H5 is the ethyl ester of acetic acid CH2COOH.

Ethers

A group of organic compounds with the general formula R-O-R' formed by the condensation of two alcohol molecules.

Explosion

A violent and rapid increase of pressure in a confined space. It may be caused by an external source of; energy (heat) or by an internal exothermic reaction in which: relatively large volumes of gases areproduced.

Explosives

Substances that undergo a rapid chemical change with production of gas on being, heated or struck .

Fatigue of Metals

The deterioration of metals owing to repeated stresses above a certain critical value, it is accompanied by changes in the crystalline structure of the metal.

Filtrate

The liquid obtained after filtration.

Flux

Material which permits another substance to melt more easily.

Formula

The composition of a substance indicated by symbols of each element present and subscript numbers showing the number of each type of atom involved.

Freezing

Point Temperature at which a liquid changes to a solid.

Fertilisers

Materials put into 'the soil to; provide compounds of elements essential to plant life more I particularly nitrogen, phosphorus and potassium.

Fire

A chemical reaction accompanied by the evolution of heat, light and flame (i.e. a glowing mass of gas). It is generally applied to the chemical combination with oxygen 'of carbon and other elements' constituting the substance being burnt.

Flammable

Substances with flash point < 80 °FJ i Those having P.P. > 80 °F are called' combustibles. Flash Point The lowest temperature at which a I substance gives off sufficient inflammable vapour to produce a momentary flash when a small flame is applied.

Flue

Gas The gaseous products of combustion from a boiler furnace consisting predo-minantly of CO2, CO, O2, N2 and steam. Analysis of the flue ~ gases is used to check the efficiency of the furnace.

Fluid

A substance that takes the shape of the shape of the vessel containing it, a liquid or gas.

Fuel

A substance used for producing heat energy, either by means or the release of its chemical energy by combustion or its nuclear energy by nuclear fission.

Fungicide

A substance capable of destroying I harmful fungi, such as moulds and mildews.

Gas

A substance whose physical state (the gaseous state) is such that it always occupies the whole of the ; space in which it is contained.

Gas

Mask Respirator a device for protecting the face and breathing organs against poisonous gases. Germicide A substance capable of destroying bacteria.

Halide

A binary compound of one of the halogen elements (fluorine, chlorine, bromine or iodine), a salt of the hydride of one of these elements.

Heat

Energy possessed by a substance in the form of kinetic energy of atomic or molecular translation, rotation or vibration. The heat contained by a body is the product of its mass, temperature and specific heat capacity. It is expressed in joules, calories or B.Th. U. Heat is transmitted by conduction,; convection and radiation. Its physical effects are rise in temperature, change of state from solid to liquid (melting), solid to gas (sublimation), liquid to gas (evaporation), boiling, expansion and electrical effects.

100

Heat exchanger

Any device that transfers heat from one. fluid to another without allowing the fluids to come into contact with each other.

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Heat of reaction

The quantity of heat given out (exothermic) or absorbed in (endothermic) a chemical reaction usually per mole of reacting substances.

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Herbicides

Substances that kill plants or inhibit their growth. Selective herbicides affect only particular plant types, making it possible to attack weed growing among cultivated plants.

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Heterocyclic compounds

Organic compounds containing e compounds ring structure of atoms in the molecule, the ring including atoms of elements other than carbon e.g. C5H5N.

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Homocyclic compounds

Organic compounds the molecules compounds of which contain a ring structure of atoms of the same kind (usually carbon), e.g. benzene C6H6.

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Homologous

Series A series of chemical compounds of uniform chemical type, showing a regular gradation in physical [properties and represented by a general molecular formula, the! molecule of each member of the series differing from the preceding one by a definite constant group of atoms, e.g. the alkanes. Members of the same homologous series are called homologous, e.g. methane CH4, and ethane C2H6.

106

Hydrocarbons

Organic compounds that contain only carbon and hydrogen. They are classified as either aliphatic or aromatic compounds (or a combination of both). Hydrocarbons may be either saturated or unsaturated compounds.

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Imide

Imido compound , a compound derived from ammonia, containing the imido group. NH, in which the two hydrogen atoms of ammonia are replaced by non acidic organic radicals.

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Inert or noble gases

Rare gases, helium, neon, argon, gases krypton, xenon, radon. They are all chemically inactive, though some compounds have been reported.

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Ion

An atom which has acquired an electrical charge as a result of the gain or loss of electrons; a charged atom or radical.

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Isotopes

Atoms of an element having the same chemical properties but differing in mass number are different isotopes of the element.

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Insecticide

A substance used for killing insect pests.

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Isomerism

The existence of two or more chemical compounds with the same molecular formula but having different properties owing to a different arrangement of atoms within the molecule, e.g. ammonium cyanate NH4CNO and urea CO (NH2)2 are isomers.

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Latent heat

The quantity of heat absorbed or released in an isothermal transformation of phase.

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Liquid

A state of matter intermediate between a solid and a gas, in which the molecules are relatively free to move with respect to each other but are restricted by cohesive I forces to the extent that the liquid maintains a fixed volume. Liquids assume the shape of the vessel containing them, but are only slightly compressible.

115

Local effect

Effect confined to affected part (chemical burn, dermatitis) .

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Malleability

The ability to be hammered out into thin sheets.

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Matter

A specialised form of energy that has the attributes of mass and extension in space and time.

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Melting point

The constant temperature at which the solid and liquid phase of a substance are in equilibrium at a given pressure. Melting points are normally quoted for standard atmospheric pressure.

119

Metalv

Element which readily loses electrons to form positive ions; conductor of electricity.

120

Metalloid

Element possessing characteristics of both metals and non-metals .

121

Mixture

A combination of substances held together by physical rather than by chemical means.

123

Molecule

Smallest particle of a compound capable of having the properties of the compound.

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Monomer

A chemical compound consisting of single molecules, as opposed to a polymer, the molecules of which are built up by the repeated union of monomer molecules.

125

Noble metals

Metals such as silver, gold and platinum, that do not corrode or tarnish in air or water and are not easily attacked by acids.

126

Non-metal

Element which readily gains electrons to form negative ions; nonconductor of electricity.

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Pesticides

Substances that kill pests. They include insecticides.

128

pH.

Logarithm of the reciprocal of the I molar concentration of the hydrogen ion; a scale indicating the acidity of a solution; if pH is less than 7 solution is acidic, if pH is 7 solution, is neutral, if pH is greater than 7 solution is alkaline.

129

Physical change

An alteration of the properties of a substance without affecting the substance itself.

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Precipitate

A solid which forms in and settles out from a solution.

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Products

The substances formed as a result of a chemical change.

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Petrochemicals

Chemical substances derived from petroleum (or natural gas).

133

Petroleum

Mineral oil. A natural mixture of hydrocarbons and other organic compounds. Fractional disti-llation yields petrol, paraffin oil, lubricating oil, petrolatum and paraffin wax.

134

Plasticizer

(1) A non-volatile liquid added to I paints and varnishes to prevent brittleness of the dried film.
(2) A liquid or solid substance added to synthetic or natural resins to modify their flow properties.

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Polymerisation

The chemical union of two or more molecules of the same compound to form larger molecules, resulting in the formation of a new compound of the same imperial formula but of greater molecular weight, e.g. Paraldehyde (CH,CHO), is formed by the polymerisation of acetaldehyde CH,CHO monomer. It includes addition polymerisation, condensation polymerisation and copolymerisation. Many important products such as plastics and textile fibres consist of polymeric substance, either natural (e.g. cellulose) or synthetic (e.g. nylon).

136

Pressure

The force per unit area acting on a surface. Absolute pressure is the pressure measured with respect to zero pressure. Gauge pressure is the pressure measured by a gauge in excess of the pressure of atmosphere.

137

Radical

A group of elements bonded together which behave chemically as a single atom.

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Radioactivity

The breakdown of the nucleus of an atom through the emission of alpha, beta and gamma rays.

139

Reducing agent

A substance that removes oxygen from, or adds hydrogen to, another substance.

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Refrigerant

A fluid used in the refrigerating cycle of a refrigerator, usually of a liquid that will vaporise at a low temperature, e.g. freon or ammonia.

141

Relative density

Specific gravity. The ratio of the density of solid or liquid at a specified temperature (often 20°C) to the density of water at the temperature of its maximum density (4oC).

142

Salt

Compound which ionises, but which produces neither hydrogen nor hydroxide ions in solution.

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Solubility

The extent to which a solute can dissolve in a solvent; the concentration of a saturated solution of a given solute.

146

Solution

Homogeneous, non-setting mixture of two ingredients, solute and solvent.

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Solvent

The medium in which a substance is dissolved.

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Stable

Relatively inert; hard to decompose.

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Synthesis

The formation of a compound by combining elements or more simple compounds.

150

Skin Poisons

Cause dermatitis and ulcer to skin (Chromates, Naphtha, Amines, Aniline etc.,)

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Soda

Washing soda Na2CO3, backing soda, NaHCO3, caustic soda NaOH.

152

Soda ash

The common name for anhydrous Na2CO3.

153

Soda lime

A solid mixture of NaOH and Ca(OH)2

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Specific heat capacity

Specific heat capacity divided by mass. The quantity of heat required to raise the temperature of unit mass of a substance by one degree.

155

Systemic effect

Effect on one complete or more than one systems, (exposure to CO, H2S, Benzene, Aniline, Methanol etc.)

156

Temperature

Temperature is a measure of hotness of a body. It can be defined as a property determining the rate at which heat will be transferred to or from it. Temperature is thus a measure of the kinetic energy of the molecules, atoms or ions of which matter is composed.

157

Thermo-dynamics

The study of the general laws governing processes that involve heat changes and the conservation of energy.

158

Toxic

Poisonous, toxicology - the study of poison, toxin-poison.

159

Toxic dusts

Dust of asbestos, silica, coal, cotton, iron, lead, sugarcane hay can cause lung diseases.

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Toxicity

Ability of a chemical to cause internal or external injury on human body.

161

Vapour

A substance in the gaseous state that can be liquefied by increasing the pressure without altering the temperature. A gas below its critical. temperature.

162

Vapour density

A measure of the density of a gas or vapour, usually, given relative to Oxygen or hydrogen or air.

163

Vermicide

A substance used to kill worms.

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Viscosity

The property of a fluid whereby it tends to resist relative motion within itself.

165

Volatile

Forms a gas with case.

156

Water gas

A fuel gas obtained by the action of steam on glowing hot coke. It consists of CO and H.

23st feb 2024 by admin

Fire Prevention

The main factors for combustions are presence of oxygen, availability of combustible materials and rise of temperature to the ignition point for the material The cause of fire accidents may be electric-short circuit.

23st feb 2024 by admin

Personal Protective Equipment

23st feb 2024 by admin

Health Hazards and control measures in Industrial Areas

Effects of dusts, fumes, heat, noise and vibration due to hot and cold working of metals and crush and other injuries due to machine tools are discussed earlier.

24st feb 2024 by admin

First Aid

sometimes accidents may also occur in industries. After major or minor accidents, an injured worker requires immediate preliminary treatment in the absence of same his condition may become highly critical.

24st feb 2024 by admin

Cupola Furnace

sA Cupola furnace is utilized for melting recycled metal or pig iron to manufacture diverse cast irons. Crucial factors in choosing cupolas include melting capability, shell diameter with or without lining, and spark arrestor.

24st feb 2024 by admin

Antidotes for some common Chemicals

Antidotes are therapeutic agents used to counteract the toxic effects of specific xenobiotics. These are heterogenous group of substances consisting of pharmaceuticals, biological agents and immunoglobulin fragments.

21st feb, 2024 by admin