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AQA - Chemistry Unit 4 > Definitions > Flashcards

Definitions Flashcards

(57 cards)

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1
Q

Achiral molecule

A

A molecule that can be superimposed on its mirror image

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2
Q

Acid anhydride

A

A molecule formed from two identical carboxylic acid molecules joined via an oxygen atom

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3
Q

Acid dissociation constant (Ka)

A

An equilibrium constant specific to weak acids that relates the acid concentration to the concentration of [H⁺] ions.
Ka = [H⁺]{HA⁻] ÷ [HA]

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4
Q

Acidic buffer

A

A buffer with pH of less than 7 made by mixing a weak acid with one of its salts.

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5
Q

Acyl chloride

A

A molecule which contains the functional group COCl

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6
Q

Addition polymer

A

A type of polymer formed by joining small alkenes together

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7
Q

Amide

A

A carboxylic acid derivative which contains the functional group CONH₂

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8
Q

Amine

A

A molecule where one or more of the hydrogen atoms in ammonia have been replaced with an organic functional group

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9
Q

Amino acid

A

A molecule with an amino group (NH₂) and a carboxyl group (COOH)

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10
Q

Basic buffer

A

A buffer with pH of more than 7 made by mixing a weak base with one of its salts

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11
Q

Biodiesel

A

A mixture of methyl esters of fatty acids which can be used as a carbon neutral fuel

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12
Q

Cationic surfactant

A

A surfactant which is positively charged

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13
Q

Chemical shift

A

Nuclei in different environments absorb energy of different frequencies. NMR spectroscopy measures these differences relative to a standard substance - this difference is called the chemical shift.

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14
Q

Chromatography

A

An analytical technique which uses a mobile phase and a stationary phase to separate out mixtures

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15
Q

Deuterated solvent

A

A solvent which has had all of its hydrogen atoms exchanged for deuterium atoms.

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16
Q

Deuterium

A

An isotope of hydrogen. It contains one neutron, one proton and one electron.

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17
Q

Electrophile

A

An electron deficient (usually positively charged) species which is attracted to regions of high electron density

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18
Q

Electrophilic substitution

A

A reaction mechanism when an electrophile substitutes for a hydrogen atom in a molecule

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19
Q

Enantiomer

A

A molecule that has the same structural formula as another molecule but with four groups arranged around a chiral carbon compound atom so that it is a non-superimposable mirror image of the other molecule.

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20
Q

Ester

A

A molecule that contains the functional group RCOOR

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21
Q

Esterification

A

Forming an ester by heating a carboxylic acid and an alcohol in the presence of a strong acid catalyst

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22
Q

Equilibrium constant Kc

A

A ratio worked out from the concentration of the products and reactants once a reversible reaction has reached equilibrium

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23
Q

Fatty acid

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A

A long chain carboxylic acid which can combine with glycerol to for a fat or an oil

24
Q

Fragment ion

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A

A charged fragment produced when a molecular ion breaks up inside a mass spectrometer

25
Infrared (IR) spectroscopy
An analytical technique used to identify the functional groups present in a molecule by measuring the frequency of energy absorbed by its bonds
26
Integration trace
A line on an ¹H NMR spectrum that has a change in height that is proportional to the area of the peak it's next to
27
Ionic product of water Kw
A constant generated by multiplying the Hc for the dissociation of water by [H₂O] Kw = [H⁺][OH⁻]
28
Isoelectric point
The pH at which the average overall charge on a molecule is zero
29
M peak
The peak on a mass spectrum that is caused my the molecular ion
30
Mass spectrometry
An analytical technique used to find the structure of a molecule by looking at the pattern of ions it produces when it is bombarded with electrons
31
Mass spectrum
A chart produced by a mass spectrometer giving information on relative isotopic mass and relative abundance of isotopes.
32
Mobile phase
A liquid or gas in chromatography which contains molecules that can move
33
n+1 rule
Peaks on a ¹H NMR spectrum always split into the number of hydrogens on the neighbouring carbon, plus one
34
N-substituted amides
A amide where one of the hydrogens attached to the nitrogen has been substituted with another functional group
35
Nitration
A reaction in which a nitro group (NO₂) is added to a molecule
36
Nuclear Magnetic Resonance (NMR) spectroscopy
An analytical technique which uses the nuclear spin of a nucleus to determine the relative environment of the nucleus in a compound.
37
Nuclear spin
Any nucleus that contains an odd number of protons and neutrons will spin on its axis creating a weak magnetic field.
38
Nucleophile
A species that forms a bond with an electrophile by donating a pair of electrons
39
Nucleophilic addition
A reaction mechanism where a nucleophile adds on to the partially positive carbon atom of a carbonyl compound
40
Nucleophilic addition-elimination
A reaction mechanism where a nucleophile adds onto the partially positive carbon atom of a carbonyl compound and another nucleophile is eliminated.
41
Nucleophilic substitution
A reaction mechanism where a nucleophile substitutes for an atom (or group of atoms) in a molecules
42
Optical isomer
A molecule that has the same structural formula as another molecule but with four groups arranged around a chiral carbon atom that is a non-superimposable mirror image of the other molecule
43
Paper chromatography
A technique which can used to separate out mixtures of different compounds
44
pH
A measure of the hydrogen ion concentration in solution | pH = -log[H⁺]
45
Plane-polarised light
Light in which all the waves are vibrating in the same plane
46
Polyamide
A polymer formed from reactions between dicarboxylic acids and diamines
47
Polyester
A polymer formed from reactions between dicarboxylic acids and diols
48
Polypeptide
A polymer formed from reactions between amino acids
49
Racemate
A mixture that contains equal quantities of each enantiomer of an optically active compound
50
Rate constant (k)
A constant in the rate equation. The larger it is, the after the rate of reaction.
51
Rate determining step
The slowest step in a reaction mechanism which determines to overall rate of reaction
52
Retention
The process of being adsorbed onto the stationary phase in chromatography
53
Retention time
The time taken for a component of a mixture to pass through a chromatography column to the detector at the other end
54
Splitting pattern
Peaks in ¹H NMR spectra may be split into further peaks. The resultant group of peaks is called a splitting pattern
55
Stationary phase
A solid, or a liquid held in a solid, used in chromatography which contains molecules that can't move
56
Surfactant
A compound which is partly soluble and partly insoluble in water
57
Zwitterion
A dipolar ion which has both a negative and a positive charge in different parts of the molecule.

AQA - Chemistry Unit 4 (1 decks)

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