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Chemistry Definitions > Definitions > Flashcards

Definitions Flashcards

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1
Q

Endothermic

A

A reaction in which the enthalpy of the products is greater than the enthalpy of the reactants

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2
Q

Exothermic

A

A reaction in which the enthalpy of the products is less than the enthalpy of reactants

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3
Q

Conservation of Energy

A

Energy can neither be created or destroyed, it can only be transformed from one form to another

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4
Q

Hess’ law

A

The enthalpy change of a reaction is independent of the route taken provided initial and final conditions remain the same

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5
Q

Standard Conditions

A

298K, 100Kpa

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6
Q

Standard enthalpy change

A

Heat energy change at constant pressure under standard conditions

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7
Q

Enthalpy of formation

A

Enthalpy change when one mole of compound is formed from its constituent elements under standard condtions (100kpa, 298K)

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8
Q

Enthalpy of combustion

A

Enthalpy change when one mole of substance is burnt completely in oxygen under standard conditions (298k, 100kpa)

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9
Q

Enthalpy of neutralisation

A

Enthalpy change when one mole of water is produced in a neutralisation reaction under standard conditions (298k, 100kpa)

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10
Q

1st ionisation reaction

A

Energy change when one mole of gaseous atoms is converted into gaseous ions with a singly positive charge.

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11
Q

1st electron affinity

A

Energy change when one mole of gaseous atoms is converted into gaseous ions with a singly negative charge

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12
Q

Bond dissociation energy

A

energy change required to break one mole of a specific bond

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13
Q

average bond enthalpy

A

energy change required to break one mole of a specific bond averaged over many compounds

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14
Q

Enthalpy of atomisation

A

enthalpy change when one mole of gaseous atoms is formed from its element in its standard state under standard conditions

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15
Q

Lattice enthalpy

A

Enthalpy change when one mole of ionic compound is converted into gaseous ions

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16
Q

Enthalpy of solution

A

Enthalpy change when one mole of solute dissolves in water

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17
Q

Enthalpy of hydration

A

Enthalpy change when one mole of gaseous ions is converted into one mole of aqueous ions.

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18
Q

Feasible/aqueous

A

A reaction for which ^G<0

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19
Q

Entropy(s)

A

a measure of disorder/ randomness

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20
Q

Gibbs free energy

A

^G= ^H - T^S

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21
Q

Isomers

A

Compounds with same formula but a different arrangement of atoms within compound

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22
Q

Structural isomers

A

Compounds with same molecular formula but different structural formula

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23
Q

Stereoisomers

A

same structural formula but a different arrangement of atoms in space

24
Q

Geometric isomers

A

same structural formula but a different arrangement of atoms in space due to the presence of at least 1 C=C

25
Q

E/Z or Cis/Trans isomerism

A

Restricted rotation around the C=C bonds in the compound. each atom of C=C has 2 different atoms/ groups of atoms attached.

26
Q

Optical isomers

A

super-imposable mirror images of one another, have an asymmetric centre.

27
Q

Asymmetric/ chiral centre

A

atom bonded to 4 different atoms/groups of atoms in a tetrahedral arrangement.

28
Q

optically active

A

sample which rotates the plane of plane polarised light

29
Q

Racemic mixture

A

50;50 mixture of 2 optical isomers

30
Q

optically inactive

A

optical isomers are in a 50;50 mixture, they rotate the plane of plane polarised light in equal but opposite directions.

31
Q

Stereospecific

A

active site only bonds when the molecules have a particular orientation/ shape.

32
Q

reflux

A

repeated boiling and condensing of a reaction mixture

33
Q

hydrolysis

A

breaking up molecules by their reaction with water

34
Q

nucleophile

A

molecule with a lone pair of electrons, which attacks regions of low electron density

35
Q

hydrogenation

A

addition of a hydrogen molecule across C=C

36
Q

elimination

A

a reaction in which a smaller molecule is removed from a larger molecule

37
Q

electrophile

A

ion/molecule which attacks regions of high electron density

38
Q

substitution

A

replacement of an atom/ group of atoms with another atom/ group of atoms

39
Q

delocalisation (arenes)

A

pie electrons are spread over several atoms

40
Q

chromophore

A

group of atoms and electrons forming part of an organic molecule which causes it to be coloured

41
Q

conjugation

A

special stability associated with 3 or more adjacent, parallel, overlapping p orbitals, resulting in increased electron delocalisation and longer electron wavelength.

42
Q

Reduction

A

Loss of oxygen, gain of hydrogen

43
Q

Nucleophile

A

Ion/molecule with a lone pair of electrons which attacks regions of low electron density

44
Q

Addition

A

Pie bond of double bond broken and species added

45
Q

Hydrolysis

A

Splitting bonds using water

46
Q

Monoester

A

Ester which contains only one ester group

47
Q

Transesterification

A

Reaction where alkyl group of an ester is exchanged with alkyl group of an alcohol

48
Q

Biodiesel

A

Fuel similar to diesel, made from vegetable sources eg; the reaction of rapeseed oil and methanol

49
Q

Delocalisation

A

Pie electrons spread over several atoms

50
Q

Hydrolysis

A

Breaking up molecules by their reaction with water

51
Q

Hydrogenation

A

Addition of hydrogen molecules across C=C

52
Q

Condensation reaction

A

2 molecules combine to form one large molecule while releasing a small molecule eg; H2O, HCl

53
Q

Triglyceride

A

Chemical compound which contains 1 molecule of glycerol and 3 fatty acids

54
Q

Saturated

A

Contains no C=C or C triple bond C

55
Q

Monounsaturated

A

Molecule contains one C=C per molecule

56
Q

Polyunsaturated

A

Molecule contains 2 or more C=C per molecule

57
Q

Saponification

A

Alkaline hydrolysis of a fat/oil

Chemistry Definitions (2 decks)

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