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This question is about shapes of molecules and ions.
1.
Draw the shape of NCl3 and of NCl4+
Include any lone pairs of electrons that influence the shape.
Name the shape of NCl3
State and explain the bond angle in NCl4+
Shape of NCl3 Shape of NCl4+
Name of shape of NCl3 ___________________________________________________
Bond angle in NCl4+ ______________________________________________________
Explanation of bond angle in NCl4+ __________________________________________
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(Total 5 marks)
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This question is about structure and bonding.
2.
(a) Draw a diagram to show the strongest type of interaction between two molecules of ethanol
(C2H5OH) in the liquid phase.
Include all lone pairs and partial charges in your diagram.
(3)
(c) Methoxymethane (CH3OCH3) is an isomer of ethanol.
The table shows the boiling points of ethanol and methoxymethane.
Compound Boiling point / °C
ethanol 78
methoxymethane −24
In terms of the intermolecular forces involved, explain the difference in boiling points.
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(3)
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(c) Draw the shape of the POCl3 molecule and the shape of the ClF4⁻ ion.
Include any lone pairs of electrons that influence the shapes.
In a POCl3 molecule the oxygen atom is attached to the phosphorus atom by a double
bond that uses two electrons from phosphorus.
Name each shape.
Suggest a value for the bond angle in ClF4⁻
Shape of POCl3 Shape of ClF4⁻
Name of shape of POCl3 ______________________________________________
Name of shape of ClF4⁻ _______________________________________________
Bond angle in ClF4⁻ __________________________________________________
(5)
(Total 11 marks)
Sodium thiosulfate reacts with dilute hydrochloric acid as shown.
3.
Na2S2O3(aq) + 2 HCl(aq) → 2 NaCl(aq) + SO2 (g) + S(s) + H2O(l)
(a) Give the simplest ionic equation for this reaction.
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(1)
(b) The gas SO2 is a pollutant.
State the property of SO2 that causes pollution when it enters rivers.
Give an equation to show the reaction of SO2 with water.
Property ___________________________________________________________
Equation __________________________________________________________
(2)
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(c) Draw a diagram to show the shape of a molecule of H2O
Include any lone pairs of electrons.
State the H-O-H bond angle.
Explain this shape and bond angle.
Diagram
Bond angle _________________________________________________________
Explanation _________________________________________________________
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(4)
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(d) The initial rate of the reaction between sodium thiosulfate and hydrochloric acid can be
monitored by measuring the time taken for a fixed amount of sulfur to be produced.
Describe an experiment to investigate the effect of temperature on the initial rate of this
reaction.
Include
• a brief outline of your method
• how you will measure the time taken for a fixed amount of sulfur to be formed
• how you will present your results in graphical form
• a sketch of the graph that you would expect.
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(6)
(Total 13 marks)
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This question is about compounds containing fluorine.
4.
(a) Draw the shape of a molecule of krypton difluoride (KrF2).
Include in your answer any lone pairs of electrons that influence the shape.
Name the shape produced by the atoms in a KrF2 molecule and suggest a bond angle.
Name of shape ______________________________________________________
Bond angle _________________________________________________________
(3)
(b) There are two lone pairs of electrons on the oxygen atom in a molecule of oxygen difluoride
(OF2).
Explain how the lone pairs of electrons on the oxygen atom influence the bond angle in
oxygen difluoride.
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(2)
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(c) Silicon tetrafluoride (SiF4) is a tetrahedral molecule.
Deduce the type of intermolecular forces in SiF4
Explain how this type of intermolecular force arises and why no other type of intermolecular
force exists in a sample of SiF4
Intermolecular forces in SiF4 ____________________________________________
Explanation _________________________________________________________
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(3)
(Total 8 marks)
This question is about intermolecular forces.
5.
(a) Give the meaning of the term electronegativity.
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(1)
(b) Explain how permanent dipole-dipole forces arise between hydrogen chloride molecules.
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(2)
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(c) Complete the table by naming the shape of each molecule.
Place a tick (✔) in the final column if the molecule has a permanent dipole.
✔) if molecule has a
Tick (✔
Molecule Name of shape
permanent dipole
SiH4
PH3
BeCl2
CH3Cl
(4)
(Total 7 marks)
Aluminium and thallium are elements in Group 3 of the Periodic Table.
6. Both elements form compounds and ions containing chlorine and bromine.
(a) Write an equation for the formation of aluminium chloride from its elements.
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(1)
(b) An aluminium chloride molecule reacts with a chloride ion to form the AlCl4− ion.
Name the type of bond formed in this reaction. Explain how this type of bond is formed in
the AlCl4− ion.
Type of bond ________________________________________________________
Explanation _________________________________________________________
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(2)
(c) Aluminium chloride has a relative molecular mass of 267 in the gas phase.
Deduce the formula of the aluminium compound that has a relative molecular mass of 267
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(1)
(d) Deduce the name or formula of a compound that has the same number of atoms, the same
number of electrons and the same shape as the AlCl4− ion.
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(1)
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(e) Draw and name the shape of the TlBr52− ion.
Shape of the TlBr52− ion.
Name of shape ______________________________________________________
(2)
(f) (i) Draw the shape of the TlCl2+ ion.
(1)
(ii) Explain why the TlCl2+ ion has the shape that you have drawn in part (f)(i).
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(1)
(g) Which one of the first, second or third ionisations of thallium produces an ion with the
electron configuration [Xe] 5d106s1?
Tick ( ) one box.
First
Second
Third
(1)
(Total 10 marks)
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