PHYSICAL CHEMISTRY/ GUIDE STUDY NOTES
LATEST UPDATES/ WITH VERIFIED SOLUTIONS AND
CORRECT ACTUALIZATION.
Original
Fluorine forms compounds with many other elements.
(a) Fluorine reacts with bromine to form liquid bromine trifluoride (BrF3).State the type of bond
between Br and F in BrF3 and state how this bond is formed.
Covalent
Shared pair(s) of electrons / one electron from Br and one electron from F
Two molecules of BrF3 react to form ions as shown by the following equation.
2BrF3 -> BrF2+ + BrF4-
(i) Draw the shape of BrF3 and predict its bond angle.Include any lone pairs of electrons that influence
the shape.
Draw the shape of BrF4- and predict its bond angle.Include any lone pairs of electrons that influence the
shape.
BrF4- ions are also formed when potassium fluoride dissolves in liquid BrF3 to form KBrF4
Explain, in terms of bonding, why KBrF4 has a high melting point.
Ionic or (forces of) attraction between ions / bonds between ions
If molecules, IMF, metallic, CE =0
,If covalent bonds mentioned, 0/3, unless specified within the BrF4– ion and not broken
Strong (electrostatic) attraction / strong bonds / lots of energy needed to breakbonds
Between K+ and BrF4– ions/oppositely charged ions / + and – ions
If ions mentioned they must be correct
Strong bonds between + and – ions =3/3
Fluorine reacts with hydrogen to form hydrogen fluoride (HF).
(i) State the strongest type of intermolecular force between hydrogen fluoride molecules.
Hydrogen bonds/hydrogen bonding/H bonds/H bonding
Draw a diagram to show how two molecules of hydrogen fluoride are attracted to each other by the
type of intermolecular force that you stated in part (d)(i). Include all partial charges and all lone pairs of
electrons in your diagram.
The boiling points of fluorine and hydrogen fluoride are -188 °C and 19.5 °C respectively.Explain, in
terms of bonding, why the boiling point of fluorine is very low.
vdw / van der Waals forces between molecules
QoL
,Not vdw between HF molecules, CE = 0/2
vdw between atoms, CE = 0/2
If covalent, ionic, metallic, CE=0/2
IMF are weak / need little energy to break IMF / easy to overcome IMF
Phosphorus exists in several different forms, two of which are white phosphorus and red phosphorus.
White phosphorus consists of P4 molecules, and melts at 44°C. Red phosphorus is macromolecular, and
has a melting point above 550°C.
Explain what is meant by the term macromolecular. By considering the structure and bonding present in
these two forms of phosphorus, explain why their melting points are so different.
M1 macromolecule = a giant/massive/huge molecule/lattice/structurewith covalent bonding
(in words, not diagram)
(not just ‘very large’)
(not ‘molecules bonded together’/reference to ions)
M2 White: IMF = van der Waals’
M3 which are weak
(tied to ‘IMF’ or van der Waals’ in M2)
, (if H-bonding or dipole-dipole, treat as CE, M2 = M3 = 0)
M4 Red: (covalent) bonds must be broken/overcome
(not weakened / loosened)
M5 (covalent) bonds are strong [tied to M4]
Or there are many (covalent) bonds
Or much energy is required to.
The structure below shows the repeating unit of a polymer.
By considering the functional group formed during polymerisation, name this type of polymer and the
type of polymerisation involved in its formation.
polyamide or nylon (2,4)
(allow nylon without numbers but if numbers are present they must be correct)
Draw the structure of the species present in solid aminoethanoic acid, H2NCH2COOH
LATEST UPDATES/ WITH VERIFIED SOLUTIONS AND
CORRECT ACTUALIZATION.
Original
Fluorine forms compounds with many other elements.
(a) Fluorine reacts with bromine to form liquid bromine trifluoride (BrF3).State the type of bond
between Br and F in BrF3 and state how this bond is formed.
Covalent
Shared pair(s) of electrons / one electron from Br and one electron from F
Two molecules of BrF3 react to form ions as shown by the following equation.
2BrF3 -> BrF2+ + BrF4-
(i) Draw the shape of BrF3 and predict its bond angle.Include any lone pairs of electrons that influence
the shape.
Draw the shape of BrF4- and predict its bond angle.Include any lone pairs of electrons that influence the
shape.
BrF4- ions are also formed when potassium fluoride dissolves in liquid BrF3 to form KBrF4
Explain, in terms of bonding, why KBrF4 has a high melting point.
Ionic or (forces of) attraction between ions / bonds between ions
If molecules, IMF, metallic, CE =0
,If covalent bonds mentioned, 0/3, unless specified within the BrF4– ion and not broken
Strong (electrostatic) attraction / strong bonds / lots of energy needed to breakbonds
Between K+ and BrF4– ions/oppositely charged ions / + and – ions
If ions mentioned they must be correct
Strong bonds between + and – ions =3/3
Fluorine reacts with hydrogen to form hydrogen fluoride (HF).
(i) State the strongest type of intermolecular force between hydrogen fluoride molecules.
Hydrogen bonds/hydrogen bonding/H bonds/H bonding
Draw a diagram to show how two molecules of hydrogen fluoride are attracted to each other by the
type of intermolecular force that you stated in part (d)(i). Include all partial charges and all lone pairs of
electrons in your diagram.
The boiling points of fluorine and hydrogen fluoride are -188 °C and 19.5 °C respectively.Explain, in
terms of bonding, why the boiling point of fluorine is very low.
vdw / van der Waals forces between molecules
QoL
,Not vdw between HF molecules, CE = 0/2
vdw between atoms, CE = 0/2
If covalent, ionic, metallic, CE=0/2
IMF are weak / need little energy to break IMF / easy to overcome IMF
Phosphorus exists in several different forms, two of which are white phosphorus and red phosphorus.
White phosphorus consists of P4 molecules, and melts at 44°C. Red phosphorus is macromolecular, and
has a melting point above 550°C.
Explain what is meant by the term macromolecular. By considering the structure and bonding present in
these two forms of phosphorus, explain why their melting points are so different.
M1 macromolecule = a giant/massive/huge molecule/lattice/structurewith covalent bonding
(in words, not diagram)
(not just ‘very large’)
(not ‘molecules bonded together’/reference to ions)
M2 White: IMF = van der Waals’
M3 which are weak
(tied to ‘IMF’ or van der Waals’ in M2)
, (if H-bonding or dipole-dipole, treat as CE, M2 = M3 = 0)
M4 Red: (covalent) bonds must be broken/overcome
(not weakened / loosened)
M5 (covalent) bonds are strong [tied to M4]
Or there are many (covalent) bonds
Or much energy is required to.
The structure below shows the repeating unit of a polymer.
By considering the functional group formed during polymerisation, name this type of polymer and the
type of polymerisation involved in its formation.
polyamide or nylon (2,4)
(allow nylon without numbers but if numbers are present they must be correct)
Draw the structure of the species present in solid aminoethanoic acid, H2NCH2COOH
