atomicity
atomicity [CHEM] The number of atoms in a molecule of a compound. { adəmis
əde¯ }
əde¯ }
31.12.16
atomic hydrogen
atomic hydrogen [CHEM] Gaseous hydrogen whose molecules are dissociated into
atoms. { əta¨mik hı¯drəjən }
atoms. { əta¨mik hı¯drəjən }
atomic heat capacity
atomic heat capacity [PHYS CHEM] The heat capacity of a gram-atomic weight of an
element. { ə ta¨m ik he¯t kə pas əd e¯ }
element. { ə ta¨m ik he¯t kə pas əd e¯ }
atomic fluorescence spectroscopy
atomic fluorescence spectroscopy [SPECT] A form of atomic spectroscopy in which
the sample atoms are first excited by absorbing radiation from an external source
containing the element to be detected, and the intensity of radiation emitted at
characteristic wavelengths during transitions of these atoms back to the ground
state is observed. { ə¦ta¨m ik flu˙ ¦res əns spek tra¨s kə pe¯ }
the sample atoms are first excited by absorbing radiation from an external source
containing the element to be detected, and the intensity of radiation emitted at
characteristic wavelengths during transitions of these atoms back to the ground
state is observed. { ə¦ta¨m ik flu˙ ¦res əns spek tra¨s kə pe¯ }
atomic connectivity
atomic connectivity [PHYS CHEM] The specific pattern of chemical bonds between
atoms in a molecule. { ə¦ta¨m ik kə nek tiv əd e¯ }
atoms in a molecule. { ə¦ta¨m ik kə nek tiv əd e¯ }
atomic absorption spectroscopy
atomic absorption spectroscopy [SPECT] An instrumental technique for detecting concentrations
of atoms to parts per million by measuring the amount of light absorbed
by atoms or ions vaporized in a flame or an electrical furnace. { ə¦ta¨ mik əb¦so¨ rp
shən spek tra¨s kə pe¯ }
of atoms to parts per million by measuring the amount of light absorbed
by atoms or ions vaporized in a flame or an electrical furnace. { ə¦ta¨ mik əb¦so¨ rp
shən spek tra¨s kə pe¯ }
atom cluster
atom cluster [PHYS CHEM] An assembly of between three and a few thousand atoms
or molecules that are weakly bound together and have properties intermediate
between those of the isolated atom or molecule and the bulk or solid-state material.
{ ad əm kləs tər }
or molecules that are weakly bound together and have properties intermediate
between those of the isolated atom or molecule and the bulk or solid-state material.
{ ad əm kləs tər }
asymmetry effect
asymmetry effect [PHYS CHEM] The asymmetrical distribution of the ion cloud around
an ion that results from the finite relaxation time for the ion cloud when a voltage
is applied; leads to a reduction in ion mobility. { a¯ sim ə tre¯ i fekt }
an ion that results from the finite relaxation time for the ion cloud when a voltage
is applied; leads to a reduction in ion mobility. { a¯ sim ə tre¯ i fekt }
asymmetric synthesis
asymmetric synthesis [ORG CHEM] Chemical synthesis of a pure enantiomer, or of an
enantiomorphic mixture in which one enantiomer predominates, without the use of
resolution. { ¦a¯ sə¦me trik sin thə səs }
enantiomorphic mixture in which one enantiomer predominates, without the use of
resolution. { ¦a¯ sə¦me trik sin thə səs }
asymmetric carbon atom
asymmetric carbon atom [ORG CHEM] A carbon atom with four different atoms or groups of atoms bonded to it. Also known as chiral carbon atom; stereogenic center. { ¦a¯ sə¦me trik ¦ka¨ r bən ad əm }
astronomical spectroscopy
astronomical spectroscopy [SPECT] The use of spectrographs in conjunction with telescopes
to obtain observational data on the velocities and physical conditions of
astronomical objects. { as trə na¨m ə kəl spek tra¨s kə pe¯ }
to obtain observational data on the velocities and physical conditions of
astronomical objects. { as trə na¨m ə kəl spek tra¨s kə pe¯ }
astronomical spectrograph
astronomical spectrograph [SPECT] An instrument used to photograph spectra of
stars. { as trə na¨m ə kəl spek trə graf }
stars. { as trə na¨m ə kəl spek trə graf }
astigmatic mounting
astigmatic mounting [SPECT] A mounting designed to minimize the astigmatism of a
concave diffraction grating. { ¦a stig mad ik mo˙ unt iŋ }
concave diffraction grating. { ¦a stig mad ik mo˙ unt iŋ }
association
association [CHEM] Combination or correlation of substances or functions. { ə so¯
se¯ a¯ shən }
se¯ a¯ shən }
ascending chromatography
ascending chromatography [ANALY CHEM] A technique for the analysis of mixtures of
two or more compounds in which the mobile phase (sample and carrier) rises through
the fixed phase. { ə send iŋ kro¯ mə ta¨g rə fe¯ }
two or more compounds in which the mobile phase (sample and carrier) rises through
the fixed phase. { ə send iŋ kro¯ mə ta¨g rə fe¯ }
ascaridole
ascaridole [ORG CHEM] C10H16O2 A terpene peroxide, explosive when heated; used as
an initiator in polymerization. { ə skar ə do¯ l }
an initiator in polymerization. { ə skar ə do¯ l }
aryloxy compound
aryloxy compound [ORG CHEM] One of a group of compounds useful as organic weed
killers, such as 2,4-dichlorophenoxyacetic acid (2,4-D). { ¦ar əl¦a¨ k se¯ ka¨m pau˙ nd }
killers, such as 2,4-dichlorophenoxyacetic acid (2,4-D). { ¦ar əl¦a¨ k se¯ ka¨m pau˙ nd }
aryl halide
aryl halide [ORG CHEM] An aromatic derivative in which a ring hydrogen has been
replaced by a halide atom. { ar əl hal ı¯d }
replaced by a halide atom. { ar əl hal ı¯d }
30.12.16
aryl diazo compound
aryl diazo compound [ORG CHEM] A diazo compound bonded to the ring structure
characteristic of benzene or any other aromatic derivative. { arəl dı¯a¯ zo¯
ka¨mpau˙ nd }
characteristic of benzene or any other aromatic derivative. { arəl dı¯a¯ zo¯
ka¨mpau˙ nd }
aryl compound
aryl compound [ORG CHEM] Molecules with the six-carbon aromatic ring structure
characteristic of benzene or compounds derived from aromatics. { arəl
ka¨mpau˙ nd }
characteristic of benzene or compounds derived from aromatics. { arəl
ka¨mpau˙ nd }
arsonic acid
arsonic acid [INORG CHEM] An acid derived from orthoarsenic acid, OAs(OH)3; the type
formula is generally considered to be RAsO(OH)2; an example is para-aminobenzenearsonic
acid, NH2C6H4AsO(OH)2. {a¨ r¦sa¨nik asəd }
formula is generally considered to be RAsO(OH)2; an example is para-aminobenzenearsonic
acid, NH2C6H4AsO(OH)2. {a¨ r¦sa¨nik asəd }
arsinic acid
arsinic acid [INORG CHEM] An acid of general formula R2AsO2H; derived from trivalent
arsenic; an example is cacodylic acid, or dimethylarsinic acid, (CH3)2AsO2H. { a¨ r¦sin
ik asəd }
arsenic; an example is cacodylic acid, or dimethylarsinic acid, (CH3)2AsO2H. { a¨ r¦sin
ik asəd }
arseno compound
arseno compound [ORGCHEM] A compound containing an As-As bond with the general
formula (RAs)n, where R represents a functional group; structures are cyclic or longchain
polymers. { a¨ rs ən o¯ ka¨m pau˙ nd }
formula (RAs)n, where R represents a functional group; structures are cyclic or longchain
polymers. { a¨ rs ən o¯ ka¨m pau˙ nd }
arsenobenzene
arsenobenzene [ORG CHEM] C6H5As:AsC6H5 White needles that melt at 212 C; insoluble
in cold water, soluble in benzene; derivatives have some use in medicine. { a¨ rs
ən o¯ ben ze¯n }
in cold water, soluble in benzene; derivatives have some use in medicine. { a¨ rs
ən o¯ ben ze¯n }
arseno compound
arseno compound [ORGCHEM] A compound containing an As-As bond with the general
formula (RAs)n, where R represents a functional group; structures are cyclic or longchain
polymers. { a¨ rs ən o¯ ka¨m pau˙ nd }
formula (RAs)n, where R represents a functional group; structures are cyclic or longchain
polymers. { a¨ rs ən o¯ ka¨m pau˙ nd }
arsenobenzene
arsenobenzene [ORG CHEM] C6H5As:AsC6H5 White needles that melt at 212 C; insoluble
in cold water, soluble in benzene; derivatives have some use in medicine. { a¨ rs
ən o¯ ben ze¯n }
in cold water, soluble in benzene; derivatives have some use in medicine. { a¨ rs
ən o¯ ben ze¯n }
arsenic trisulfide
arsenic trisulfide [INORG CHEM] As2S3 An acidic compound in the form of yellow or
red monoclinic crystals with a melting point at 300 C; occurs as the mineral orpiment;
used as a pigment. { a¨ rs ən ik tri səl fı¯d }
red monoclinic crystals with a melting point at 300 C; occurs as the mineral orpiment;
used as a pigment. { a¨ rs ən ik tri səl fı¯d }
arsenic trioxide
arsenic trioxide [INORG CHEM] As2O3 A toxic compound, slightly soluble in water; octahedral
crystals change to the monoclinic form by heating at 200 C; occurs naturally
as arsenolite and claudetite; used in small quantities in some medicinal preparations.
Also known as arsenic oxide; arsenious acid. { a¨ rs ən ik tri a¨ k sı¯d }
crystals change to the monoclinic form by heating at 200 C; occurs naturally
as arsenolite and claudetite; used in small quantities in some medicinal preparations.
Also known as arsenic oxide; arsenious acid. { a¨ rs ən ik tri a¨ k sı¯d }
arsenic trichloride
arsenic trichloride [INORG CHEM] AsCl3 An oily, colorless liquid that dissolves in water;
used in ceramics, organic chemical syntheses, and in the preparation of pharmaceuticals.
{ a¨ rs ən ik tri klo˙ r ı¯d }
used in ceramics, organic chemical syntheses, and in the preparation of pharmaceuticals.
{ a¨ rs ən ik tri klo˙ r ı¯d }
arsenic pentoxide
arsenic pentoxide [INORG CHEM] As2
O5 A white, deliquescent compound that decomposes
by heat and is soluble in water. Also known as arsenic oxide. { a¨ rs ən
ik pent a¨ k sı¯d }
O5 A white, deliquescent compound that decomposes
by heat and is soluble in water. Also known as arsenic oxide. { a¨ rs ən
ik pent a¨ k sı¯d }
arsenic pentasulfide
arsenic pentasulfide [INORG CHEM] As2
S5 Yellow crystals that are insoluble in water
and readily decompose to the trisulfide and sulfur; used as a pigment. { a¨ rs ən
ik pent ə səl fı¯d }
S5 Yellow crystals that are insoluble in water
and readily decompose to the trisulfide and sulfur; used as a pigment. { a¨ rs ən
ik pent ə səl fı¯d }
arsenic oxide
arsenic oxide [INORG CHEM] 1. An oxide of arsenic. 2. See arsenic pentoxide; arsenic
trioxide. { a¨ rs ən ik a¨ k sı¯d }
trioxide. { a¨ rs ən ik a¨ k sı¯d }
arsenic disulfide
arsenic disulfide [INORG CHEM] As2
S2 Red, orange, or black monoclinic crystals, insoluble
in water; used in fireworks; occurs naturally as realgar. { a¨ rs ən ik dı¯ səl fı¯d }
S2 Red, orange, or black monoclinic crystals, insoluble
in water; used in fireworks; occurs naturally as realgar. { a¨ rs ən ik dı¯ səl fı¯d }
arsenic acid
arsenic acid [INORG CHEM] H3AsO41/2H2O White, poisonous crystals, soluble in water
and alcohol; used in manufacturing insecticides, glass, and arsenates and as a
defoliant. Also known as orthoarsenic acid. { a¨ rsenik asəd }
and alcohol; used in manufacturing insecticides, glass, and arsenates and as a
defoliant. Also known as orthoarsenic acid. { a¨ rsenik asəd }
Arrhenius equation
Arrhenius equation [PHYS CHEM] The relationship that the specific reaction rate constant
k equals the frequency factor constant s times exp (Hact /RT), where Hact
is the heat of activation, R the gas constant, and T the absolute temperature. { arra¯
ne¯ əs ikwa¯ zhən }
k equals the frequency factor constant s times exp (Hact /RT), where Hact
is the heat of activation, R the gas constant, and T the absolute temperature. { arra¯
ne¯ əs ikwa¯ zhən }
aroylation
aroylation [ORG CHEM] A reaction in which the aroyl group is incorporated into a
molecule by substitution. { arəwəla¯ shən }
molecule by substitution. { arəwəla¯ shən }
aromatic nucleus
aromatic nucleus [ORG CHEM] The six-carbon ring characteristic of benzene and related
series, or condensed six-carbon rings of naphthalene, anthracene, and so forth.
{ ¦ar ə¦mad ik nu¨ kle¯ əs }
series, or condensed six-carbon rings of naphthalene, anthracene, and so forth.
{ ¦ar ə¦mad ik nu¨ kle¯ əs }
aromatic ketone
aromatic ketone [ORG CHEM] An aromatic compound containing the CO radical, such
as acetophenone. { ¦ar ə¦mad ik ke¯ to¯n }
as acetophenone. { ¦ar ə¦mad ik ke¯ to¯n }
aromatic hydrocarbon
aromatic hydrocarbon [ORG CHEM] A member of the class of hydrocarbons, of which
benzene is the first member, consisting of assemblages of cyclic conjugated carbon
atoms and characterized by large resonance energies. Also known as arene. { ¦ar
ə¦mad ik ¦hı¯ drə ka¨ r bən }
benzene is the first member, consisting of assemblages of cyclic conjugated carbon
atoms and characterized by large resonance energies. Also known as arene. { ¦ar
ə¦mad ik ¦hı¯ drə ka¨ r bən }
aromatic amine
aromatic amine [ORG CHEM] An organic compound that contains one or more amino
groups joined to an aromatic structure. { ¦ar ə¦mad ik am e¯n }
groups joined to an aromatic structure. { ¦ar ə¦mad ik am e¯n }
29.12.16
aromatic aldehyde
aromatic aldehyde [ORG CHEM] An aromatic compound containing the CHO radical,
such as benzaldehyde. { ¦ar ə¦mad ik al də hı¯d }
such as benzaldehyde. { ¦ar ə¦mad ik al də hı¯d }
aromatic alcohol
aromatic alcohol [ORG CHEM] Any of the compounds containing the hydroxyl group
in a side chain to a benzene ring, such as benzyl alcohol. { ¦ar ə¦mad ik al kə ho˙ l }
in a side chain to a benzene ring, such as benzyl alcohol. { ¦ar ə¦mad ik al kə ho˙ l }
Arndt-Eistert synthesis
Arndt-Eistert synthesis [ORG CHEM] A method of increasing the length of an aliphatic
acid by one carbon by reacting diazomethane with acid chloride. { ¦a¨ rnt ¦ı¯ stərt sin
thə səs }
acid by one carbon by reacting diazomethane with acid chloride. { ¦a¨ rnt ¦ı¯ stərt sin
thə səs }
armchair nanotube
armchair nanotube [PHYS CHEM] A carbon nanotube formed from a graphite sheet that
is rolled up so that the edge is in the shape of armchairs. { a¨rm cha¯ r nan o¯ tu¨b }
is rolled up so that the edge is in the shape of armchairs. { a¨rm cha¯ r nan o¯ tu¨b }
aristolochic acid
aristolochic acid [ORG CHEM] C17H11NO7 Crystals in the form of shiny brown leaflets
that decompose at 281–286 C; soluble in alcohol, chloroform, acetone, ether, acetic
acid, and aniline; used as an aromatic bitter. Also known as aristolochine. { ə¦ris
tə¦la¨ k ik as əd }
that decompose at 281–286 C; soluble in alcohol, chloroform, acetone, ether, acetic
acid, and aniline; used as an aromatic bitter. Also known as aristolochine. { ə¦ris
tə¦la¨ k ik as əd }
argentometry
argentometry [ANALY CHEM] A volumetric analysis that employs precipitation of insoluble
silver salts; the salts may be chromates or chlorides. { a¨ r jən ta¨m ə tre¯ }
silver salts; the salts may be chromates or chlorides. { a¨ r jən ta¨m ə tre¯ }
argentocyanides
argentocyanides [INORG CHEM] Complexes formed, for example, in the cyanidation of
silver ores and in electroplating, when silver cyanide reacts with solutions of soluble
metal cyanides. Also known as dicyanoargentates. { a¨ r jen to¯ sı¯ ə nı¯dz }
silver ores and in electroplating, when silver cyanide reacts with solutions of soluble
metal cyanides. Also known as dicyanoargentates. { a¨ r jen to¯ sı¯ ə nı¯dz }
arc spectrum
arc spectrum [SPECT] The spectrum of a neutral atom, as opposed to that of a molecule or an ion; it is usually produced by vaporizing the substance in an electric arc;
designated by the roman numeral I following the symbol for the element, for example,
HeI. { a¨ rk spek trəm }
designated by the roman numeral I following the symbol for the element, for example,
HeI. { a¨ rk spek trəm }
aqueous solution
aqueous solution [CHEM] A solution with the solvent as water. { a¯ k we¯ əs sə lu¨
shən }
shən }
aqua regia
aqua regia [INORG CHEM] A fuming, highly corrosive, volatile liquid with a suffocating
odor made by mixing 1 part concentrated nitric acid and 3 parts concentrated
hydrochloric acid; reacts with all metals, including silver and gold. { ¦a¨ k wə re¯ jə }
odor made by mixing 1 part concentrated nitric acid and 3 parts concentrated
hydrochloric acid; reacts with all metals, including silver and gold. { ¦a¨ k wə re¯ jə }
aprotic solvent
aprotic solvent [CHEM] A solvent that does not yield or accept a proton. { a¯ pra¨d ik
sa¨ l vənt }
sa¨ l vənt }
apparent concentration
apparent concentration [ANALY CHEM] The value of analyte concentration obtained
when the interference is not considered. { ə par ənt ka¨n sən tra¯ shən }
when the interference is not considered. { ə par ənt ka¨n sən tra¯ shən }
apodization
apodization [SPECT] A mathematical transformation carried out on data received from
an interferometer to alter the instrument’s response function before the Fourier
transformation is calculated to obtain the spectrum. { a pə də za¯ shən }
an interferometer to alter the instrument’s response function before the Fourier
transformation is calculated to obtain the spectrum. { a pə də za¯ shən }
apoatropine
apoatropine [ORG CHEM] C17H21NO2 An alkaloid melting at 61 C with decomposition
of the compound; highly toxic; obtained by dehydrating atropine. { ap o¯ a trə pe¯n }
of the compound; highly toxic; obtained by dehydrating atropine. { ap o¯ a trə pe¯n }
anti-Stokes lines
anti-Stokes lines [SPECT] Lines of radiated frequencies which are higher than the
frequency of the exciting incident light. { an te¯ sto¯ ks lı¯nz }
frequency of the exciting incident light. { an te¯ sto¯ ks lı¯nz }
antioxidant
antioxidant [PHYS CHEM] A substance that, when present at a lower concentration than
that of the oxidizable substrate, significantly inhibits or delays oxidative processes,
while being itself oxidized. In primary antioxidants, antioxidative activity is implemented
by the donation of an electron or hydrogen atom to a radical derivative,
and in secondary antioxidants by the removal of an oxidative catalyst and the
consequent prevention of the initiation of oxidation. Antioxidants are used in polymers
to prevent degradation, and in foods, beverages, and cosmetic products to
inhibit deterioration and spoilage. { an te¯ a¨ k sə dənt }
that of the oxidizable substrate, significantly inhibits or delays oxidative processes,
while being itself oxidized. In primary antioxidants, antioxidative activity is implemented
by the donation of an electron or hydrogen atom to a radical derivative,
and in secondary antioxidants by the removal of an oxidative catalyst and the
consequent prevention of the initiation of oxidation. Antioxidants are used in polymers
to prevent degradation, and in foods, beverages, and cosmetic products to
inhibit deterioration and spoilage. { an te¯ a¨ k sə dənt }
antimony trisulfide
antimony trisulfide [INORG CHEM] Sb2S3 Black and orange-red rhombic crystals; soluble
in concentrated hydrochloric acid and sulfide solutions, insoluble in water; melting
point 546 C; used as a pigment, and in matches and pyrotechnics. { an tə mo¯
ne¯ trı¯ səl fı¯d }
in concentrated hydrochloric acid and sulfide solutions, insoluble in water; melting
point 546 C; used as a pigment, and in matches and pyrotechnics. { an tə mo¯
ne¯ trı¯ səl fı¯d }
antimony trichloride
antimony trichloride [INORG CHEM] SbCl3 Hygroscopic, colorless, crystalline mass;
fumes slightly in air, is soluble in alcohol and acetone, and forms antimony oxychloride
in water; used as a mordant, as a chlorinating agent, and in fireproofing textiles.
{ an tə mo¯ ne¯ trı¯ klo˙ r ı¯d }
fumes slightly in air, is soluble in alcohol and acetone, and forms antimony oxychloride
in water; used as a mordant, as a chlorinating agent, and in fireproofing textiles.
{ an tə mo¯ ne¯ trı¯ klo˙ r ı¯d }
antimony sulfate
antimony sulfate [INORG CHEM] Sb2(SO4)3 Antimony(III) sulfate, a white, deliquescent
powder; soluble in acids. { an tə mo¯ ne¯ səl fa¯t }
powder; soluble in acids. { an tə mo¯ ne¯ səl fa¯t }
antimony pentasulfide
antimony pentasulfide [INORG CHEM] Sb2S5 An orange-yellow powder; soluble in alkali,
soluble in concentrated hydrochloric acid, with hydrogen sulfide as a by-product,
and insoluble in water; used as a red pigment. Also known as antimony persulfide;
antimony red; golden antimony sulfide. { an tə mo¯ ne¯ pent ə səl fı¯d }
soluble in concentrated hydrochloric acid, with hydrogen sulfide as a by-product,
and insoluble in water; used as a red pigment. Also known as antimony persulfide;
antimony red; golden antimony sulfide. { an tə mo¯ ne¯ pent ə səl fı¯d }
antimony pentafluoride
antimony pentafluoride [INORG CHEM] SbF5 A corrosive, hygroscopic, moderately viscous
fluid; reacts violently with water; forms a clear solution with glacial acetic acid;
used in the fluorination of organic compounds. { an tə mo¯ ne¯ pent ə flu˙ r ı¯d }
fluid; reacts violently with water; forms a clear solution with glacial acetic acid;
used in the fluorination of organic compounds. { an tə mo¯ ne¯ pent ə flu˙ r ı¯d }
antimony pentachloride
antimony pentachloride [INORG CHEM] SbCl5 A reddish-yellow, oily liquid; hygroscopic,
it solidifies after moisture is absorbed and decomposes in excess water; soluble in
hydrochloric acid and chloroform; used in analytical testing for cesium and alkaloids,
for dyeing, and as an intermediary in synthesis. Also known as antimony perchloride.
{ an tə mo¯ ne¯ pent ə klo˙ r ı¯d }
it solidifies after moisture is absorbed and decomposes in excess water; soluble in
hydrochloric acid and chloroform; used in analytical testing for cesium and alkaloids,
for dyeing, and as an intermediary in synthesis. Also known as antimony perchloride.
{ an tə mo¯ ne¯ pent ə klo˙ r ı¯d }
antimony(III) oxide
antimony(III) oxide [INORG CHEM] Sb2O3 Colorless, rhombic crystals, melting at 656 C;
insoluble in water; powerful reducing agent. { an tə mo¯ ne¯ thre¯ a¨ k sı¯d }
insoluble in water; powerful reducing agent. { an tə mo¯ ne¯ thre¯ a¨ k sı¯d }
antimonous
antimonous [CHEM] Pertaining to antinomy, especially trivalent antimony. { an tə
mə nəs }
mə nəs }
antimonide
antimonide [INORG CHEM] A binary compound of antimony with a more positive compound,
for example, H5Sb. Also known as stibide. { an tə mə nı¯d }
for example, H5Sb. Also known as stibide. { an tə mə nı¯d }
antimonate
antimonate [CHEM] The radical [Sb(OH)6] in salts derived from antimony pentoxide,
Sb4O10, and bases. { an tə mə na¯t }
Sb4O10, and bases. { an tə mə na¯t }
antifreeze
antifreeze [CHEM] A substance added to a liquid to lower its freezing point; the principal
automotive antifreeze component is ethylene glycol. { an te¯ fre¯z }
automotive antifreeze component is ethylene glycol. { an te¯ fre¯z }
antifoaming agent
antifoaming agent [ORG CHEM] A substance, such as silicones, organic phosphates,
and alcohols, that inhibits the formation of bubbles in a liquid during its agitation
by reducing its surface tension. { ¦an te¯ ¦fo¯m iŋ a¯ jənt }
and alcohols, that inhibits the formation of bubbles in a liquid during its agitation
by reducing its surface tension. { ¦an te¯ ¦fo¯m iŋ a¯ jənt }
anticatalyst
anticatalyst [CHEM] A material that slows down the action of a catalyst; an example
is lead, which inhibits the action of platinum. { ¦an te¯ kad əl ist }
is lead, which inhibits the action of platinum. { ¦an te¯ kad əl ist }
antiaromatic
antiaromatic [CHEM] A cyclic compound with delocalized electrons that does not obey
Hu¨ ckel’s rule, and is much less stable than similar nonaromatic compounds. { an
te¯ ar ə mad ik }
Hu¨ ckel’s rule, and is much less stable than similar nonaromatic compounds. { an
te¯ ar ə mad ik }
anthraquinone
anthraquinone [ORG CHEM] C6H4(CO)2C6H4 Yellow crystalline diketone that is insoluble
in water; used in the manufacture of dyes. { an thrə kwi no¯n }
in water; used in the manufacture of dyes. { an thrə kwi no¯n }
anthrapurpurin
anthrapurpurin [ORG CHEM] C6H3OH(CO)2C6H2(OH)2 Orange-yellow, crystalline needles
with a melting point of 369 C; soluble in alcohol and alkalies; used in dyeing.
{ an thrə pər pə rin }
with a melting point of 369 C; soluble in alcohol and alkalies; used in dyeing.
{ an thrə pər pə rin }
anthranilic acid
anthranilic acid [ORG CHEM] o-NH2C6H4COOH A white or pale yellow, crystalline acid
melting at 146 C; used as an intermediate in the manufacture of dyes, pharmaceuticals,
and perfumes. { ¦an thrə¦lin ik as əd }
melting at 146 C; used as an intermediate in the manufacture of dyes, pharmaceuticals,
and perfumes. { ¦an thrə¦lin ik as əd }
anthraciferous coal
anthraciferous coal [ORG CHEM] Anthracite-hard coal containing or yielding anthracene.
{ an thrə sif ə rəs ko¯ l }
{ an thrə sif ə rəs ko¯ l }
anthracene
anthracene [ORG CHEM] C14H10 A crystalline tricyclic aromatic hydrocarbon, colorless
when pure, melting at 218 C and boiling at 342 C; obtained in the distillation of
coal tar; used as an important source of dyestuffs, and in coating applications.
{ an thrə se¯n }
when pure, melting at 218 C and boiling at 342 C; obtained in the distillation of
coal tar; used as an important source of dyestuffs, and in coating applications.
{ an thrə se¯n }
antarafacial
antarafacial [ORG CHEM] The stereochemistry when, simultaneously, two sigma bonds
are formed or broken on the opposite faces of the component pi systems, such as
in a cycloaddition reaction. { an tə rə fa¯ shəl }
are formed or broken on the opposite faces of the component pi systems, such as
in a cycloaddition reaction. { an tə rə fa¯ shəl }
anomalous Zeeman effect
anomalous Zeeman effect [SPECT] A type of splitting of spectral lines of a light source
in a magnetic field which occurs for any line arising from a combination of terms
of multiplicity greater than one; due to a nonclassical magnetic behavior of the
electron spin. { ə na¨m ə ləs za¯ ma¨n i fekt }
in a magnetic field which occurs for any line arising from a combination of terms
of multiplicity greater than one; due to a nonclassical magnetic behavior of the
electron spin. { ə na¨m ə ləs za¯ ma¨n i fekt }
anodic polarization
anodic polarization [PHYSCHEM] The change in potential of an anode caused by current
flow. { ə na¨d ik po¯ lə rə za¯ shən }
flow. { ə na¨d ik po¯ lə rə za¯ shən }
anode film
anode film [CHEM] The portion of solution in immediate contact with the anode.
{ a no¯ d film }
{ a no¯ d film }
anode effect
anode effect [PHYS CHEM] A condition produced by polarization of the anode in the
electrolysis of fused salts and characterized by a sudden increase in voltage and a
corresponding decrease in amperage. { a no¯d i fekt }
electrolysis of fused salts and characterized by a sudden increase in voltage and a
corresponding decrease in amperage. { a no¯d i fekt }
anode-corrosion efficiency
anode-corrosion efficiency [PHYS CHEM] The ratio of actual weight loss of an anode
due to corrosion to the theoretical loss as calculated by Faraday’s law.
{ a no¯ d kə¦ro¯ zhən i fish ən se¯ }
due to corrosion to the theoretical loss as calculated by Faraday’s law.
{ a no¯ d kə¦ro¯ zhən i fish ən se¯ }
annular atoms
annular atoms [ORG CHEM] The atoms in a cyclic compound that are members of the
ring. { an yə lər ad əmz }
ring. { an yə lər ad əmz }
anisic alcohol
anisic alcohol [ORG CHEM] C8H10O2 A colorless liquid that boils in the range 255–265 C;
it is obtained by reduction of anisic aldehyde; used in perfumery, and as an intermediate
in the manufacture of pharmaceuticals. { ə nis ik al kə ho˙ l }
it is obtained by reduction of anisic aldehyde; used in perfumery, and as an intermediate
in the manufacture of pharmaceuticals. { ə nis ik al kə ho˙ l }
anisic acid
anisic acid [ORG CHEM] CH3OC6H4COOH White crystals or powder with a melting point
of 184 C; soluble in alcohol and ether; used in medicine and as an insect repellent
and ovicide. { ə nis ik as əd }
of 184 C; soluble in alcohol and ether; used in medicine and as an insect repellent
and ovicide. { ə nis ik as əd }
anisaldehyde
anisaldehyde [ORG CHEM] C6H4(OCH3)CHO A compound with melting point 2.5 C,
boiling point 249.5 C; insoluble in water, soluble in alcohol and ether; used in
perfumery and flavoring, and as an intermediate in production of antihistamines.
{ ¦a nəs al də hı¯d }
boiling point 249.5 C; insoluble in water, soluble in alcohol and ether; used in
perfumery and flavoring, and as an intermediate in production of antihistamines.
{ ¦a nəs al də hı¯d }
anionotropy
anionotropy [CHEM] The breaking off of an ion such as hydroxyl or bromide from a
molecule so that a positive ion remains in a state of dynamic equilibrium. { ¦a nı¯
ə na¨ trə pe¯ }
molecule so that a positive ion remains in a state of dynamic equilibrium. { ¦a nı¯
ə na¨ trə pe¯ }
anionic polymerization
anionic polymerization [ORG CHEM] A type of polymerization in which Lewis bases,
such as alkali metals and metallic alkyls, act as catalysts. { ¦a nı¯¦a¨n ik pə lim ə
rə za¯ shən }
such as alkali metals and metallic alkyls, act as catalysts. { ¦a nı¯¦a¨n ik pə lim ə
rə za¯ shən }
Determination of Barium: Direct Titration using Methyl Thymol Blue as indicator
Determination of Barium: Direct Titration using Methyl Thymol Blue as indicator
can you determine the barium ion by EDTA titration
determine the concentration of barium ions in a solution by direct titration with methyl thymol blue
you can determine the barium ion in sulfate by determination of barium sulfate,determination of barium sulphate, determination of barium in water and determination of barium in drinking water by this method
PRINCIPLE:
Complexometric titration of Barium(II) ions directly with EDTA can only be
effected in alkaline solution since the complex is broken down in acidic media. Methyl
Thymol Blue is used as indicator which is grey when it is free (H4ln) and blue when
complexed with Barium.
REAGENTS:
1- Barium ions solution (analyte)
2- 1M sodium hydroxide solution (pH 12)
3- Methyl Thymol Blue indicator
4- 0.01 M EDTA solution
PROCEDURE:
1- Pipette 25.0 mL of Barium ions solution into a 250.0 mL and dilute to about
100mL with de-ionised water. Adjust the pH of the solution to 12 by the
addition of 3-6 mL of 1M sodium hydroxide solution.
2- Add 50 mg of methyl thymol blue indicator.
3- Titrate with 0.01 M EDTA until the color changes from blue to grey. Record
the used volume (as VEDTA).
4- Repeat the titration twice
Atomic weight of Barium = 137.34 g/mol
.....................................
source : Yallascience.com
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