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A Level Chemistry (OCR) - Memorise > A2 Definitions > Flashcards

A2 Definitions Flashcards

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1
Q

Adic dissociation constant Ka

A

The equilibrium constant that shows the externt of dissociation of a weak acid.
For a weak acid HA,
Ka=[H+(aq)][A-]/[HA(aq)]

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2
Q

Acid-base pair

A

A pair of two species that transform into each other by gain or loss of a proton

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3
Q

Bronsted-Lowry acid

A

A species that is a proton, H+, donor

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4
Q

Bronsted-Lowry base

A

A species that is a proton, H+, acceptopr

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5
Q

Buffer solution

A

A system that minimises pH changes on addition of small amounts of an acid or a base

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6
Q

Chemical shift

A

A scale, in ppm, that compares the frequency of an NMR absorption with the frequencey of the reference TMS at delta=0ppm.

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7
Q

Chiral Carbon

A

A carbon atom attached to four different atoms or groups of atoms

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8
Q

Chromatogram

A

A visible record showing the result of separation of the components of a mixture by chromatography

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9
Q

Complex ion

A

A transition metal ion bonded to ligands by coordinate bonds (Dative covalent bonds)

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10
Q

Concentration

A

The amount of solute, in moles, dissolved in 1dm^3 (1000cm^3) of solution

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11
Q

Condensation reaction

A

A reaction in qhich two small molecules react together to form a larger molecule with elimination of a small molecule such as water

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12
Q

COnjugate acid

A

A species that releases a proton to form a conjugate base

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13
Q

Conjugate base

A

A species that accepts a proton to form a conjugate acid

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14
Q

Coordination number

A

The total number of coordinate bonds formed between a central metal ion and ligandsa

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15
Q

Electrophilic substitution

A

A type of substitution reaction in which an electrophile is attracted to an electron-rich centre or atom, where it accepts a pair of electrons to form a new covalent bond,

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16
Q

Ethantiomers

A

Stereoisomers that are non-superimposable mirror images of each other
ALSO KNOWN AS OPTICAL ISOMERS

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17
Q

End point

A

The point in a titreation where the indicator changes colour’ the end point indicates when the reaction is just complete

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18
Q

Entropy S

A

The used for the dispersal of energy and disorder within the chemicals making up a chemical sustem

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19
Q

Equivalence point

A

The point in a titration atr which the volume of one solution has reacted exactly with the volume of the second solution

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20
Q

Esterification

A

A reaction in which a carboxylic acid reacts with an alcohol to form an ester and water

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21
Q

First electron affinity

A

The enthalpy change that takes place when one electron is added to each atom in one mole of gaseous atoms to form one mole of gasesous 1- ions

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22
Q

First ionisation energy

A

The energy reqwuired to remove one electron from each atom in one mole of gaseous atoms of an element to form one mole og gaseous 1+ ions

23
Q

First ionisation energy

A

The energy required to remove one electron from each atom in one mole of gaseous atoms of an element to form one mole og gaseous 1+ ions

24
Q

Free energy change DeltaG

A

The balance between enthalpy, entroly and temperature for a process gfiven by
DeltaG=DeltaH-TDeltaS
PROCESS IS FEASIBLE WHEN DELTAG<0

25
Q

Half life3

A

The time taken for the concentration of a reactant t decrease by halg

26
Q

Heterogeneous equilibrium

A

An equilibrium uin which the species making up the reactants and products have different physical states

27
Q

Homogeneous equilibrium

A

An equilibrium in which all the species making up the reactants and products have the same physical state

28
Q

Hydrolysis

A

A rA reaction with water that breaks a chemical compound into two compounds, the H and OH in a water molecule becomes incorporated into the two compounds

29
Q

Initial rate of reaction

A

The change inconcentration of a reactant or product per unit time at the start of the reaction t=0

30
Q

Ionic product of water Kw

A

The product of the ions formed in the partial dissociation of water given by K1=[H+(aq)][OH-(aq)]

31
Q

Lattice enthalpy

A

The enthalpy change that accompanies the formatio of one mole of an ionic compound from its gaseous ions under standard conditions

32
Q

Ligand

A

A molecule or ion that cvan donate a pair of electrons to the transitino metal ion

33
Q

Ligand substritution

A

A reaction in which one or more ligands in a complex ion are replaced by different ligands

34
Q

Mobile phase

A

The phase that moves in chromatography

35
Q

Optical isomers

A

Stereoisomers that arae non superimposable mirror images of each other
ALSO CALLED ENANTIOMERSS

36
Q

Order

A

The power to which the concentration of a reactant is raised in the rate equation

37
Q

Overall order

A

The sum of the individual orders of reactants in the rate equation m+n

38
Q

pH

A

The expression

pH=-log[H+(aq)]

39
Q

Precipitation reaction

A

The formation of a solid from a solution during a chemical reaction. Precipitates are often formed when two aqueous solutions are mixed together

40
Q

Rate constant k

A

The constant that links the rate of reaction with the concentrations of the reactants raised to the powers of their orders in the rate equation

41
Q

Rate equation

A

For a reaction: A+B->C with orders m for A and n for B, the rate equation is given by
rate=k[A]^m[B]^n

42
Q

Rate=determining step

A

The slowest step in the reaction mechanism of a multi-step reaction

43
Q

Retention time

A

In gas chromatography, the time for a component to pass from the column inlet to the detector

44
Q

Rf value

A

Distance moved by component divided by the distance moved by solvent
component/solvent

45
Q

Second electron affinity

A

The enthalpy chgange that takes place when one elecvtron is added to each ion in one mole og gaseous 1- ions to form one mole of gaseous 2- ions

46
Q

Second ionisation energy

A

The energy required to remove one electron from each ion in one mole of gaseous 1+ ions of an element to form one mole of gaseous 2+ ions

47
Q

Spin-spin coupling

A

In an NMR spectrum, the interaction between spin states of non-equivalent nuclei that results in the splitting of a signal

48
Q

Standard conditions

A

A pressure of 100kPa, a stated temperature, usually 298K (25degreesC) and a concentration of 1 moldm-3 and a gas pressure of 100kPa

49
Q

Standard enthalpy chgange of atomisation

A

The enthalpy change that takes place when one mole of gaseous atoms form s frrom the element in its standard state

50
Q

Standard enthalpy change of formation DeltafH

A

The enthalpyu change that takes place when one mole of a compound is formed from its consitituent elements in their standard states uinder standar5d condition

51
Q

Standard enthalpu change of hydration

A

The enthalpy change that takes place when one mole of isolated gaseous ions is dissolbed in water forming one mole of aqueous ions under standard conditions

52
Q

Standard enthalpyu change of solution

A

The enthalpy change that takes place when one mole of a compound is completely dissolved in watrerr under standard conditions

53
Q

Stationary phase

A

The phase that does not move in chromatography

54
Q

Transition element

A

A d-block elemtnt which forms an ion with an incomplete d sub-shell

A Level Chemistry (OCR) - Memorise (3 decks)

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