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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
What do trans isomers have?
The same groups on opposite sides
26
What is cis-platin an example of?
An anti-cancer drug
27
What ligands can be found on cis-platin?
Two chloride ligands and two ammonia ligands
28
Which ligands on cis-platin are easy to replace?
The two chloride ligands
29
What are the chloride ligands on cis-platin replaced with?
Two nitrogen atoms on the DNA molecule of the cancerous cell causing the cell to die
30
What is a disadvantage of cis-platin?
It prevents normal cells from reproducing
31
What does ligand substitution usually cause?
A colour change
32
What happens to the coordination number in ligand substitution reactions if ligands are the same size?
It stays the same
33
What happens if the ligands in à ligand substitution are different sizes?
There’s a change in coordination number and a change in shape
34
What type of ion does haemophilia contain?
Fe 2+
35
How many coordinate bonds do iron II ions form?
6
36
Where do four of the lone pairs in the haemoglobin come from?
The nitrogen atoms in the haem group
37
Where does the fifth line pair come from in haemoglobin?
A nitrogen atom on a protein (globin)
38
Where does the final lone pair come from in haemoglobin?
The water ligand
39
What happens to the haemoglobin in the lungs?
The oxygen concentration is high so the water ligand is substituted for an oxygen molecule.
40
What is haemoglobin called when it contains oxygen?
Oxygaemoglobin
41
What is carboxyhaemoglobin?
Haemoglobin with a CO ligand instead of water
42
Why is carboxyhaemoglobin bad?
It is a string ligand so no the haemoglobin can no longer exchange oxygen anymore
43
How is Fe 2+ oxidised to Fe 3+?
Acidified potassium manganate (VII)
44
How is Fe 3+ reduced to Fe 2+?
By iodide ions
45
How can the Cr 3+ ion in [Cr(OH)6] 3- be oxidised to chromate (VI) solution and what is the colour change?
Warm hydrogen peroxide solution in alkaline conditions | Dark green to yellow
46
What happens when dilute sulfureux acid is added to the chromate (VI) solution?
It produces orange dichromate (VI) solution
47
How is dichromate (VI) solution reduced to Cr 3+? | Give the colour change
Acidified zinc | Orange to green
48
How is Cu 2+ reduces to copper (I) iodide? | Give the colour change
Using aqueous iodide ions | Pale blue to off white ppt
49
What does Cu+ do?
It is unstable and spontaneously disproportionate to produce Cu solid and Cu2+ aqueous
50
How can you identify transition metal ions with sodium hydroxide?
Ass NaOH solution drop wise from a pipette to a test tube
51
What colour is the Cu 2+ ion when sodium hydroxide is added?
Blue ppt
52
What colour are Fe 2+ ions in NaOH?
Green ppt
53
What colour are Fe 3+ ions in NaOH?
Orange ppt
54
What colour are Mn 2+ ions in NaOH?
Pink ppt
55
What colour are Cr 3+ ions in NaOH?
Grey-green ppt
56
What is the test for a carbonate?
Add nitric acid to the test compound | Bubble any has given off through limewater
57
What is the observation for the carbonate test?
Limewater turns from clear to cloudy if carbonate is present due to CO2 gas
58
How do you test for halides?
Add silver nitrate to the test compound
59
What colour observations do you get when testing for halides?
Chloride gives a white ppt Bromide gives a cream ppt Iodide gives a yellow ppt
60
How do you test for a sulfate ion?
Add barium nitrate or barium chloride
61
What observation can be seen if a sulfate is present?
White ppt forms
62
How can you test for ammonium ions?
Add cold NaOH to the test compound and warm | Hold red litmus paper over the solution
63
What observation can be seen when testing for ammonium ions?
Red litmus paper turns blue in the presence of ammonia
64
What is in a hydrogen half cell?
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
First ionisation energy
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
Factors that affect ionisation energy
Atomic radius Nuclear charge Electron shielding
67
Second ionisation energy
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
First electron affinity
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
Why are ionisation energies endothermic?
Energy is required to overcome the attraction between a negative electron and the positive nucleus.
70
Why are first electron affinities exothermic?
The electron being added is attracted to the nucleus
71
Why are second electron affinities endothermic?
The negative ion repels the second electron | Energy is needed to force the negatively charged electron into the negative ion
72
Effect of ionic size on lattice enthalpy
Ionic radius increases down the group Attraction between ions decreases Lattice energy less negative Melting point decreases
73
Effect of ionic charge on lattice enthalpy
Ionic charge increases Attraction between ions increases Lattice energy becomes more negative Melting point increases
74
Effect of ionic size on enthalpy of hydration
Ionic radius increases Attraction between ion and water molecules decreases Hydration enthalpy less negative
75
Effect of ionic charge on hydration enthalpy
Ionic charge increases Attraction with water molecules increases Hydration energy becomes more negative
76
Is bond breaking exo or endothermic?
Energy is required to break bonds | Bond breaking is endothermic
77
Is bond making exo or endothermic?
Energy is released when making bonds | Bond making is exothermic
78
Covalent bonding
The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
79
Ionic bonding
The electrostatic attraction between positive and negative ions
80
Dative covalent bond
A covalent bond in which the shared pair of electrons has been supplied by one of the bonding atoms only
81
What electronegativity difference gives an ionic bond?
Greater than 1.8
82
How does the conjugate base remove acid in the buffer solution?
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
How does the weak acid in the buffer solution remove added alkali?
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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