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Definitions Flashcards

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1
Q

Standard électrode potential

A

The e.m.f. of a half-cell compared with a standard hydrogen half cell measured at 298K with solution concentrations of 1mol dm-3 and a gas pressure of 100kPa

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2
Q

Standard conditions

A

100kPa
298 K
1 moldm-3

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3
Q

End point

A

The point in a titration where the indicator changes colour

Indicates when the reaction is just complete

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4
Q

Equivalence point

A

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

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5
Q

Transition element

A

A d-block element that can form at least one stable ion with an incomplete d sub-shell

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6
Q

Why do transition elements have variable oxidation states?

A

The energy levels of the 4s and 3D sub shells are very close to each other

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7
Q

Why do transition elements and their compounds make good catalysts?

A

They can change oxidation states

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8
Q

What happens when you mix transition metal ions with aqueous sodium hydroxide or aqueous ammonia?

A

A coloured hydroxide precipitate forms

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9
Q

Colour change for copper II

A

Pale blue solution to a blue precipitate

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10
Q

What does [Cu(OH)2(H2O)4] s form when reacted in excess ammonia?

A

[Cu(NH3)4(H2O)2]2+ aq

Dark blue

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11
Q

What colour solution does iron II form?

A

Pale green solution to green ppt

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12
Q

Colour change for iron III

A

Yellow solution to an orange ppt

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13
Q

Manganèse II colour change

A

Pale pink solution to a pink ppt

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14
Q

Chromium III colour change

A

Green solution to grey-green precipitate

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15
Q

What happens to the green-grey chromium III precipitate in excess NaOH?

A

It forms an aqueous dark green coloured solution

Cr(OH)6 3-

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16
Q

What happens to what happens to the green grey ppt on excess ammonia?

A

It forms a purple coloured solution

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17
Q

Complex ion

A

A metal ion surrounded by coordinately bondés ligands

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18
Q

Coordinate bond

A

A covalent bond in which both electrons in the shared pair come from the same atom

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19
Q

Ligand

A

An atom, ion or molecule that donates a pair of electrons to a central metal atom/ion

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20
Q

Coordination number

A

The number of coordinate bonds that are formed with the central metal atom or ion

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21
Q

What must a ligand have?

A

At least one line pair of electrons

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22
Q

When does optical isomerism occur in complex ions?

A

Occurs in complex ions with three bidentate ligands attached to the central ion

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23
Q

What shaped ligands can show cis/trans isomerism?

A

Square planar and octahedral complex ions that have at least two pairs of ligands

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24
Q

What do cis isomers have?

A

The same groups on the same side

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25
Q

What do trans isomers have?

A

The same groups on opposite sides

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26
Q

What is cis-platin an example of?

A

An anti-cancer drug

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27
Q

What ligands can be found on cis-platin?

A

Two chloride ligands and two ammonia ligands

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28
Q

Which ligands on cis-platin are easy to replace?

A

The two chloride ligands

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29
Q

What are the chloride ligands on cis-platin replaced with?

A

Two nitrogen atoms on the DNA molecule of the cancerous cell causing the cell to die

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30
Q

What is a disadvantage of cis-platin?

A

It prevents normal cells from reproducing

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31
Q

What does ligand substitution usually cause?

A

A colour change

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32
Q

What happens to the coordination number in ligand substitution reactions if ligands are the same size?

A

It stays the same

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33
Q

What happens if the ligands in à ligand substitution are different sizes?

A

There’s a change in coordination number and a change in shape

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34
Q

What type of ion does haemophilia contain?

A

Fe 2+

35
Q

How many coordinate bonds do iron II ions form?

A

6

36
Q

Where do four of the lone pairs in the haemoglobin come from?

A

The nitrogen atoms in the haem group

37
Q

Where does the fifth line pair come from in haemoglobin?

A

A nitrogen atom on a protein (globin)

38
Q

Where does the final lone pair come from in haemoglobin?

A

The water ligand

39
Q

What happens to the haemoglobin in the lungs?

A

The oxygen concentration is high so the water ligand is substituted for an oxygen molecule.

40
Q

What is haemoglobin called when it contains oxygen?

A

Oxygaemoglobin

41
Q

What is carboxyhaemoglobin?

A

Haemoglobin with a CO ligand instead of water

42
Q

Why is carboxyhaemoglobin bad?

A

It is a string ligand so no the haemoglobin can no longer exchange oxygen anymore

43
Q

How is Fe 2+ oxidised to Fe 3+?

A

Acidified potassium manganate (VII)

44
Q

How is Fe 3+ reduced to Fe 2+?

A

By iodide ions

45
Q

How can the Cr 3+ ion in [Cr(OH)6] 3- be oxidised to chromate (VI) solution and what is the colour change?

A

Warm hydrogen peroxide solution in alkaline conditions

Dark green to yellow

46
Q

What happens when dilute sulfureux acid is added to the chromate (VI) solution?

A

It produces orange dichromate (VI) solution

47
Q

How is dichromate (VI) solution reduced to Cr 3+?

Give the colour change

A

Acidified zinc

Orange to green

48
Q

How is Cu 2+ reduces to copper (I) iodide?

Give the colour change

A

Using aqueous iodide ions

Pale blue to off white ppt

49
Q

What does Cu+ do?

A

It is unstable and spontaneously disproportionate to produce Cu solid and Cu2+ aqueous

50
Q

How can you identify transition metal ions with sodium hydroxide?

A

Ass NaOH solution drop wise from a pipette to a test tube

51
Q

What colour is the Cu 2+ ion when sodium hydroxide is added?

A

Blue ppt

52
Q

What colour are Fe 2+ ions in NaOH?

A

Green ppt

53
Q

What colour are Fe 3+ ions in NaOH?

A

Orange ppt

54
Q

What colour are Mn 2+ ions in NaOH?

A

Pink ppt

55
Q

What colour are Cr 3+ ions in NaOH?

A

Grey-green ppt

56
Q

What is the test for a carbonate?

A

Add nitric acid to the test compound

Bubble any has given off through limewater

57
Q

What is the observation for the carbonate test?

A

Limewater turns from clear to cloudy if carbonate is present due to CO2 gas

58
Q

How do you test for halides?

A

Add silver nitrate to the test compound

59
Q

What colour observations do you get when testing for halides?

A

Chloride gives a white ppt
Bromide gives a cream ppt
Iodide gives a yellow ppt

60
Q

How do you test for a sulfate ion?

A

Add barium nitrate or barium chloride

61
Q

What observation can be seen if a sulfate is present?

A

White ppt forms

62
Q

How can you test for ammonium ions?

A

Add cold NaOH to the test compound and warm

Hold red litmus paper over the solution

63
Q

What observation can be seen when testing for ammonium ions?

A

Red litmus paper turns blue in the presence of ammonia

64
Q

What is in a hydrogen half cell?

A

H2 (g) at 298K and 100kPa
Platinum electrode
Glass tube with holes to allow H2 gas bubbles to escape
Acid solution containing 1.0 mol dm-3 H+ aqueous

65
Q

First ionisation energy

A

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

66
Q

Factors that affect ionisation energy

A

Atomic radius
Nuclear charge
Electron shielding

67
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 gaseous 2+ ions

68
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 gaseous 1- ions

69
Q

Why are ionisation energies endothermic?

A

Energy is required to overcome the attraction between a negative electron and the positive nucleus.

70
Q

Why are first electron affinities exothermic?

A

The electron being added is attracted to the nucleus

71
Q

Why are second electron affinities endothermic?

A

The negative ion repels the second electron

Energy is needed to force the negatively charged electron into the negative ion

72
Q

Effect of ionic size on lattice enthalpy

A

Ionic radius increases down the group
Attraction between ions decreases
Lattice energy less negative
Melting point decreases

73
Q

Effect of ionic charge on lattice enthalpy

A

Ionic charge increases
Attraction between ions increases
Lattice energy becomes more negative
Melting point increases

74
Q

Effect of ionic size on enthalpy of hydration

A

Ionic radius increases
Attraction between ion and water molecules decreases
Hydration enthalpy less negative

75
Q

Effect of ionic charge on hydration enthalpy

A

Ionic charge increases
Attraction with water molecules increases
Hydration energy becomes more negative

76
Q

Is bond breaking exo or endothermic?

A

Energy is required to break bonds

Bond breaking is endothermic

77
Q

Is bond making exo or endothermic?

A

Energy is released when making bonds

Bond making is exothermic

78
Q

Covalent bonding

A

The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

79
Q

Ionic bonding

A

The electrostatic attraction between positive and negative ions

80
Q

Dative covalent bond

A

A covalent bond in which the shared pair of electrons has been supplied by one of the bonding atoms only

81
Q

What electronegativity difference gives an ionic bond?

A

Greater than 1.8

82
Q

How does the conjugate base remove acid in the buffer solution?

A

On the addition of acid, the hydrogen ion concentration increases
The hydrogen ions react with the conjugate base
The equilibrium position shifts to the left, removing most of the hydrogen ions

83
Q

How does the weak acid in the buffer solution remove added alkali?

A

The hydroxide ion concentration increases
The small concentration of hydrogen ions reacts with the hydroxide ions to form water
HA dissociates, shifting the position of equilibrium to the right to restore most of the hydrogen ions

Chemistry (5 decks)

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