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A Level Chemistry > Developing Metals > Flashcards

Developing Metals Flashcards

1
Q

a transition metal is…

A

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

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2
Q

variable oxidation state means…

A

an element that can have multiple oxidation states

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3
Q

what oxidation states can iron exist as?

A

Fe 2+ and Fe3+

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4
Q

what oxidation states can copper exist as?

A

Cu+ and Cu2+

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5
Q

transition metals form _____ ions in solution

A

coloured

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6
Q

Fe 2+ ions in solution are…

A

pale green

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7
Q

Fe 3+ ions in solution are…

A

yellow

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8
Q

Cu2+ ions in solution are…

A

blue

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9
Q

metals have giant _____ _____structures

A

metallic lattice

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10
Q

how are metallic bonds created?

A

the electrons in the outer shell are delocalised and free to move, leaving a positive metal ion. this ion is attracted to delocalised electrons and form a sea of closely packed positive ions in a sea of delocalised electrons

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11
Q

explain the order of filling of the 3d and 4s sub shell in terms of every level and spin pairing

A

The electrons fill up sub shells from the lowest energy level first. The 4S sub shell has a lower energy level than the 3D sub shell, which means it fills up first

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12
Q

write the electron configuration for Fe2+

A

1s2 2s2 2p6 3s2 3p6 3d6

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13
Q

write the electron configuration for Cu2+

A

1s2 2s2 2p6 3s2 3p6 3d9

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14
Q

copper prefers to have a ___ 3d sub shell and just ___ electron in the ___ sub shell

A

full
one
4s

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15
Q

write a method to determine the concentration of Fe2+ ions in a solution of iron chloride by titration

A
  1. put 25cm3 of iron chloride in conical flasks using pipette
  2. fill burette with standard solution of KMnO4
  3. add KMnO4 until permanent colour change to pink
  4. Record volume added
  5. Repeat for concordant results
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16
Q

why is zinc not classified as a transition metal?

A

there are no zinc ions with an incomplete sub shell

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17
Q

what properties does a transition metal have?

A

•the existence of more than one oxidation state in its compounds
•the formation of coloured ions

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18
Q

a heterogenous catalyst is…

A

A catalyst that is in a different state to the reactants

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19
Q

a homogenous catalyst is…

A

A catalyst that is in the same state as the reactants

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20
Q

why are transition metals good catalysts?

A

they have multiple oxidation states so can easily gain an electron and then give it back or can easily lose an electron and gain it back

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21
Q

a ligand is…

A

a molecule or ion with an available lone pair of electrons to form a covalent bond

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22
Q

a complex ion is…

A

a transition metal ion surrounded by one or more ligands

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23
Q

a d-orbital is…

A

a space where you could find a pair of electrons in a D sub shell

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24
Q

Explain why transition metals in solution are coloured

A

ligands split the d-orbitals into slightly different energy levels, creating a small gap between energy levels. E=hv so this gap creates a wavelength in the visible range. visible frequencies absorbed and complimentary colours are transmitted

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25
Q

why are transition metal ions coloured when hydrated?

A

water off crystallisation acts as ligand causing d orbitals to split and cause a gap in energy levels in the visible range so complementary colour transmitted

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26
Q

why are transition metal ions not coloured when anhydrous?

A

anhydrous don’t have ligands so energy gap between levels is too large and out of the viable range so no cloud seen

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27
Q

explain why group 1 and 2 metals are not coloured

A

don’t have partially filled d sub shells so electrons can’t be promoted from one d orbital to another causing a split. Therefore the energy gap is too large and out of the visible range so not coloured

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28
Q

give the ionic equation for when Fe2+ reacts with NaOH solution

A

Fe2+ + 2OH- —> Fe(OH)2

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29
Q

what is observed when Fe2+ ions react with NaOH

A

green gelatinous precipitate

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30
Q

give the ionic equation for when Fe3+ reacts with NaOH solution

A

Fe3+ + 3OH- —> Fe (OH)3

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31
Q

what is observed when Fe3+ ions react with NaOH

A

orange/brown gelatinous precipitate

32
Q

give the ionic equation for when Cu2+ reacts with NaOH solution

A

Cu2+ + 2OH- —> Cu (OH)2

33
Q

what is observed when Cu2+ ions react with NaOH

A

blue gelatinous precipitate

34
Q

what is observed when Fe2+ ions react with ammonia solution

A

green gelatinous precipitate

35
Q

give the ionic equation for Fe2+ ions and ammonia solution and explain why

A

Fe2+ + 2OH- —> Fe (OH)2
the Fe 2+ doesn’t form a complex with NH3. NH3 is an alkali.

36
Q

give the ionic equation for Fe3+ ions and ammonia solution and explain why

A

Fe3+ + 3Oh- —> Fe (OH)3
the Fe 3+ doesn’t form a complex with NH3. NH3 is an alkali.

37
Q

what is observed when Fe3+ ions react with ammonia solution

A

orange/brown gelatinous precipitate

38
Q

what is observed when Cu2+ ions react with a few drops of ammonia solution

A

blue precipitate

39
Q

give the ionic equation for Cu2+ ions with a few drops of ammonia solution

A

2H2O + 2NH3 —> 2NH4+ + 2OH-

40
Q

give the ionic equation for Cu2+ ions with excess of ammonia solution

A

[Cu(H2O)6]2+ + 6NH3 —> [Cu(H2O)4(OH)2] + 6H2O

41
Q

what is observed when Cu2+ ions react with excess of ammonia solution

A

darker blue solution

42
Q

describe how to set up an experiment to determine the concentration of a Cu2+ solution using colourimetry

A

1.choose a complimentary colour filter for the colourimeter
2.make a series of known concentrations of Cu2+ and test absorbance
3. use results to plot a calibration curve
4. test the absorbance of the unknown sample and use calibration curve to find its concentration

43
Q

define standard electrode potential

A

the voltage measured under standard conditions when the half cell is connected to a standard hydrogen electrode

44
Q

how do you calculate standard cell potential

A

more positive half cell voltage - more negative half cell voltage

45
Q

what is the electrochemical series?

A

list of redox equilibrium arranged from most -ve electrode potential at the bottom and more +be at the bottom

46
Q

what are standard conditions?

A

298k temp
100kPa pressure
solutions of 1.0 mol dm-3

47
Q

what are the limitations of predicting the feasibility of redox reactions using standard electrode potential data?

A
  1. electrode potential values are at standard conditions but not all reactions occur at standard conditions
  2. doesn’t consider activation energy
48
Q

what is a salt bridge made from?

A

filter paper soaked in KNO3

49
Q

define corrosion

A

damage to the metal caused by its reaction with the environment

50
Q

give the overall equation for the rusting of iron

A

2Fe + 3O2 + 2H2O —> Fe2O3•xH2O

51
Q

explain how painting prevents rusting

A

the paint creates a barrier between the iron and the oxygen

52
Q

explain how galvanising prevents rusting

A

coating of more reactive metal which reacts to form an oxide that seals the metal below from O2

53
Q

explain how sacrificial protection prevents rusting

A

a more reactive metal is attached and oxides first protecting the other metal

54
Q

explain how plating prevents rusting

A

coating the iron in an unreactive metal, sealing if from O2

55
Q

explain how impressed current prevents rusting

A

forces the metal to become a positive electrode, the system goes forwards not allowing them to oxidise

56
Q

in rusting,
give the half equation of the formation of Fe 2+ ions
and is this oxidation or reduction

A

Fe —> Fe2+ + 2e-
oxidation

57
Q

in rusting,
give the half equation for the formation of OH- ions
and is this oxidation or reduction

A

O2 + 2H2O + 4e- —> 4OH-
reduction

58
Q

give an ionic equation for the formation of green rust

A

Fe2+ + 2OH- —> Fe(OH)2

59
Q

give the oxidation state of red/brown rust

A

+3

60
Q

suggest why in some conditions green rust forms instead of red on steel underground pipes

A

low oxygen so Fe3+ isn’t oxidised further to Fe3+

61
Q

a ligand is….

A

a molecule with a lone pair that is available to form a coordinate bond

62
Q

a complex ion is…

A

metal surrounded by ligands that are co-ordinatley bonded by a ligand donating electron to the ion

63
Q

a co-ordinate bond is…

A

a dative covalent bond between a ligand and a central metal ion

64
Q

co-ordinate number is…

A

the number of coordinate bond in a complex ion

65
Q

bidentate is…

A

two lone pairs of a ligand to form 2 coordinate bonds with a TM ion

66
Q

multidentate

A

more than two lone pairs of ligand to form more than two coordinate bonds with TM ion

67
Q

what does a species need to act as a ligand?

A

available lone pair of electrons

68
Q

explain how a coordinate bond forms

A

a ligands forms a dative covalent bond with the central TM ion by donating both electrons in the shared pair

69
Q

what shape molecule is copper hexa aqua?

A

octahedral

70
Q

explain why [Cu (H2O)6]2+ has a charge of 2+

A

Cu2+ is the central metal ion
6 ligands all neutral
so overall charge 2+

71
Q

how many co ordinate bonds does EDTA form?

A

6

72
Q

how does EDTA form a polymer chain

A

it forms 6 co ordinate bonds. 3 form in each direction to the TM ion to form a polymer chain with repeating units

73
Q

bidente ligands have a ______ shape with a bond angle of ____

A

octahedral
90 degrees

74
Q

how would chemists dissolve a iron nail and make the solution up to 1 dm3?

A

dissolve the nail in warm sulfuric acid and transfer it to a 1dm3 volumetric flask and make it up to the mark

75
Q

when a ligand substitution occurs why is there a colour change?

A

a new ligand splits p-orbitals differently

76
Q

in a bidentate ligand the shape is… and bond angle is …..

A

octahedral
90 degrees

A Level Chemistry (12 decks)

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