Unit 1 – Ionic Bonding
Unit 1 - Jan 2009
Q1.
 Which equation represents the reaction for which the enthalpy change is the lattice energy of sodium fluoride, NaF?
   A     Na(s) + ½F2(g) → NaF(s)
   B     Na(g) + F(g) → NaF(s)
   C     Na+(g) + F−(g) → NaF(s)
   D     Na(g) + ½F2(g) → NaF(s)
(Total for question = 1 mark)

Q2.
(a)  (i)   Complete the electronic configuration of the magnesium atom.
(1)
1s2
 ............................................................................................................................................. 
(ii)   Complete the electronic configuration of the chlorine atom.
(1)
1s2
 ............................................................................................................................................. 
(b)  (i)   Write the equation, including state symbols, for the reaction of magnesium with chlorine.
(2)

(ii)  Name the type of bonding present in magnesium chloride.
(1)
 ............................................................................................................................................. 
(iii)   Draw a diagram (using dots or crosses) to show the bonding in magnesium chloride.  Include ALL the electrons in each species and the charges present.
(3)

(c)  State the type of bonding that exists in solid magnesium.
(1)
Type
 ............................................................................................................................................. 
*(d)  Explain fully why the melting temperature of magnesium is higher than that of
         sodium.
(3)
............................................................................................................................................. 
 ............................................................................................................................................. 

(Total for question = 12 marks)
Q3.

Which of the following graphs shows the variation in the ionic radius of the Group 2 elements?

(Total for question = 1 mark)

Q4.
Theoretical lattice energies can be calculated from electrostatic theory.  Which of the
 following affects the magnitude of the theoretical lattice energy of an alkali metal halide,
 M+X− ?
   A     The first electron affinity of X.
   B     The first ionization energy of M.
   C     The enthalpy of atomization of M.
   D     The radius of the X− ion.
(Total for question = 1 mark)

Unit 1 - Jun 2009
Q5.
 The Born-Haber cycle for the formation of sodium chloride from sodium and chlorine may be represented by a series of steps labelled A to F as shown.

(a)  (i)  Complete the table below by adding the letters A to F next to the corresponding             energy changes.
(3)

(ii)  Calculate the first electron affinity of chlorine, in kJ mol−1, from the data given.
(2)

(b)  Lattice energies can be calculated from electrostatic theory (theoretical values) as well as by Born-Haber cycles (experimental values).

(i)  Comment on the fact that there is close agreement between the values for
      sodium chloride, NaCl.
(1)
 ............................................................................................................................................. 
............................................................................................................................................. 
*(ii)  Explain, in terms of chemical bonding, why the experimental value for silver iodide, AgI, is more exothermic than the value calculated theoretically for the same compound.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
*(c)  Suggest why the first ionization energies of the Group 1 elements decrease down the group.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 (Total for question = 10 marks)
Q6.
Which of the following does not have exactly 10 electrons?
   A     An ion of fluorine, F−
   B     A molecule of methane, CH4
   C     A molecule of nitrogen, N2
   D     An ion of sodium, Na+
(Total for question = 1 mark)

Unit 1 - Jan 2010
Q7.
The first ionization energies, in kJ mol-1, of four elements with consecutive atomic numbers are shown below.
A    1680
B    2080
C    496
D    738
(a) Which element could be an inert gas?
(1)
   A      
   B      
   C      
   D      

(b) Which element could be X in a covalent compound with formula HX?
(1)
   A      
   B      
   C      
   D      

(c) Which element could be Y in an ionic compound with formula YH2?
(1)
   A      
   B      
   C      
   D      
(Total for question = 3 marks)

Q8.
 The bonding in magnesium oxide, MgO, is
   A      ionic.
   B      metallic and ionic.
   C      ionic and covalent.
   D      metallic and covalent.
(Total for question = 1 mark)

Q9.
A drop of concentrated nickel(II) sulfate solution, which is green, is placed on moist filter paper on a microscope slide and the ends of the slide are connected to a 24 V DC power supply. After ten minutes,
   A      a blue colour has moved towards the negative terminal and a yellow colour towards the positive terminal.
   B      a blue colour has moved towards the positive terminal and a yellow colour towards the negative terminal.
   C      a green colour has moved towards the negative terminal but there is no other visible change.
   D      a green colour has moved towards the positive terminal but there is no other visible change.
(Total for question = 1 mark)

Q10.
Going down Group 1 from lithium to rubidium
   A      the radius of the atom decreases.
   B      the radius of the ion decreases.
   C      the first ionization energy decreases.
   D      the polarizing power of the ion increases.
(Total for question = 1 mark)

Q11.
Magnesium chloride can be made by reacting solid magnesium carbonate, MgCO3, with dilute hydrochloric acid.
(a) Write an equation for the reaction, including state symbols.
(2)

(b) Give TWO observations you would make when the reaction is taking place.
(2)
 ............................................................................................................................................. 
 (c) In an experiment to make crystals of hydrated magnesium chloride, MgCl2.6H2O, magnesium carbonate was added to 25 cm3 of hydrochloric acid with concentration 2.0 mol dm-3. The molar mass of magnesium carbonate is 84.3 g mol-1.
(i) How many moles of acid are used in the reaction?
(1)

(ii) What mass of magnesium carbonate, in grams, reacts with this amount of acid?
(1)

(iii) Suggest why slightly more than this mass of magnesium carbonate is used in practice.
(1)
 ............................................................................................................................................. 
 (iv) How would you separate the magnesium chloride solution from the reaction mixture in (iii)?
(1)
 ............................................................................................................................................. 

(v) The magnesium chloride solution was left to crystallise. The crystals were separated and dried carefully. A sample of 3.75g of hydrated crystals, MgCl2.6H2O, which have molar mass 203.3 g mol-1, was obtained. Calculate the percentage yield of this reaction.
(2)

(vi) Give ONE reason why the yield of crystals is less than 100%, even when pure compounds are used in the preparation.
(1)
 ............................................................................................................................................. 
(d) Lattice energies can be measured using the Born-Haber cycle, or calculated from electrostatic theory. Lattice energies of magnesium chloride and magnesium iodide are shown below.

(i) What does this data indicate about the bonding in magnesium chloride?
(1)
 ............................................................................................................................................. 
*(ii) Explain why there is a greater difference between the experimental (Born-Haber) and theoretical lattice energies for magnesium iodide, MgI2, compared with magnesium chloride.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 (e) Blood plasma typically contains 20 parts per million (ppm) of magnesium, by mass.
(i) Calculate the mass of magnesium, in grams, present in 100 g of plasma.
(1)

(ii) Magnesium chloride can be used as a supplement in the diet to treat patients with low amounts of magnesium in the blood. Suggest ONE property which makes it more suitable for this purpose than magnesium carbonate.
(1)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
(Total for question = 16 marks)

Q12.
Going across the Periodic Table from sodium to aluminium,
   A      the melting temperature increases.
   B      the radius of the atom increases.
   C      the radius of the metal ion increases.
   D      the bonding in the element changes from metallic to covalent.
(Total for question = 1 mark)

Unit 1 - Jun 2010
Q13.
Which of these equations represents the electron affinity of chlorine?
   A   Cl2(g) + 2e-  → 2Cl-(g)
   B   Cl2(g) - 2e-   → 2Cl-(g)
   C   ½Cl2(g) + e- → Cl-(g)
   D   Cl(g) + e-     → Cl-(g)
(Total for question = 1 mark)
Q14.
Which of these electron density maps best represents the bonding in the compound
 lithium iodide, LiI?

(Total for question = 1 mark)

Q15.
This question is about the properties of ions and ionic compounds.
(a) Solid calcium carbonate, CaCO3, has a giant ionic structure.
(i) Draw a diagram (using dots or crosses) for a calcium ion. Show ALL the electrons and the charge on the ion.
(2)

(ii) Complete the electronic configuration for a calcium ion.
(1)
1s2
 ............................................................................................................................................. 
(iii) Would you expect a calcium ion to be bigger, smaller or the same size as a calcium atom? Give TWO reasons to explain your answer.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 (iv) Explain why ionic compounds have relatively high melting temperatures.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 (b) Changes in the concentration of ions in a solution can be estimated by measuring the electrical conductivity of the solution.
(i) Explain why solutions of ions are able to conduct electricity.
(1)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
(ii) Suggest why aqueous solutions of calcium chloride, CaCl2(aq), and barium chloride, BaCl2(aq), of the same molar concentration, have different electrical conductivities.
(1)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 ............................................................................................................................................. 
(iii) 1 kg of a solution contains 0.100 mol of calcium ions, Ca2+.

      What is the concentration of the calcium ions by mass in parts per million (ppm)? [Assume the relative atomic mass of calcium is 40.]
(2)

.....................................ppm
*(c) Some buildings are made from limestone, which is mainly calcium carbonate. Gases in the atmosphere such as sulfur dioxide, SO2, and nitrogen dioxide, NO2, can be responsible for damaging these buildings.
        Describe how these gases come to be present in the atmosphere and explain how they can damage a limestone building.
(3)
 ............................................................................................................................................. 
............................................................................................................................................. 
 ............................................................................................................................................. 
(d) The lattice energy of calcium chloride, CaCl2, is -2258 kJ mol-1 based on an
      experimental Born-Haber cycle and -2223 kJ mol-1 based on theoretical calculations.

      Would you expect its bonding to match the ionic model? Justify your answer.
(1)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 ............................................................................................................................................. 
(Total for question = 15 marks)
Q16.
 Which of these statements is incorrect?
   A   The atomic radius of metals increases down a Group.	
   B   The trend in the melting temperature of successive elements across Period 2 is similar to that in Period 3.
   C   A metallic structure is held together by attractions between metal atoms and delocalized electrons.
   D   Na+ and O2- ions are isoelectronic.
(Total for question = 1 mark)

Q17.
Which of these ions has the greatest ability to polarize an anion?
   A   Ba2+
   B   Ca2+
   C   Cs+
   D   K+
(Total for question = 1 mark)

Unit 1 - Jan 2011
Q18.
 This question is about the element chlorine (atomic number = 17).
(a) Complete the electronic structure of chlorine.
(1)
1s2 2s2
 ............................................................................................................................................. 
(b) Chlorine forms compounds with magnesium and with carbon.
(i) Draw a dot and cross diagram to show the electronic structure of the compound magnesium chloride (only the outer electrons need be shown). Include the charges present.
(2)

(ii) Draw a dot and cross diagram to show the electronic structure of the compound tetrachloromethane (only the outer electrons need be shown).
(2)

*(iii) Suggest why the melting temperature of magnesium oxide is higher than that of magnesium chloride, even though both are almost 100% ionic.
(3)
 ............................................................................................................................................. 
............................................................................................................................................. 
(c) Magnesium chloride may be prepared from magnesium by reaction with chlorine or with hydrochloric acid. Compare these two preparations in terms of the atom economies of the reactions. No calculation is required.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 (Total for question = 10 marks)
Q19.
Element R is in Group 1 of the Periodic Table and element T is in Group 6. R and T are not the symbols for the elements.
(a) The compound of R and T will have the formula
(1)
   A      RT
   B      RT6
   C      RT2
   D      R2T

(b) The compound of R and T will have bonding which is predominantly
(1)
   A       ionic. 
   B       covalent. 
   C       dative covalent. 
   D       metallic. 

(c) In terms of its electrical conductivity, the compound of R and T will
(1)
   A       conduct when solid and liquid. 
   B       conduct when solid but not when liquid. 
   C       conduct when liquid but not when solid. 
   D       not conduct when solid or liquid. 
(Total for question = 3 marks)
Q20.
The graph below represents the successive ionization energies of an element X plotted against the number of the electron removed. X is not the symbol for the element.

(a) From this graph it is possible to deduce the group in the Periodic Table to which X belongs. X is in
(1)
   A      Group 1 
   B      Group 3 
   C      Group 5 
   D      Group 7 

(b) From the graph it is possible to deduce that the most stable ion of X will be
(1)
   A      X3+
   B      X+
   C      X−
   D      X3−
(Total for question = 2 marks)

Unit 1 - Jan 2012
Q21.
Chloroethane can be made from ethane and chlorine in the gas phase in the presence of
       ultraviolet light. The equation for the reaction is
CH3CH3 + Cl2 → CH3CH2Cl + HCl
(a) Complete the mechanism for the reaction. Two of the steps have been given for you.
(4)

(b) This reaction gives a poor yield of chloroethane. Give the structural formula and  name of another organic product, not included in your mechanism for part (a), which could be produced in the reaction.
(2)
Formula
      ..............................................................................................................................................

(c) Chlorine gas is extremely toxic and is therefore a significant hazard. The preparation
             must be performed so as to minimise the risk to the experimenter.
     (ii)   Explain the difference between hazard and risk.
(2)
      ..............................................................................................................................................
      ..............................................................................................................................................
      ..............................................................................................................................................
      ..............................................................................................................................................
    (ii)   Give one precaution that you would use in this experiment to minimise the risk,
                  other than the use of a laboratory coat and safety goggles.
(1)
      ..............................................................................................................................................
      ..............................................................................................................................................
(Total for question = 9 marks)

Q22.
(a)  Briefly describe an experiment, with a diagram of the apparatus you would use, which shows that there are oppositely charged ions in copper(II) chromate(VI), CuCrO4. Describe what you would expect to see.

(4)
Diagram
      ..............................................................................................................................................
      ..............................................................................................................................................
      ..............................................................................................................................................
      ..............................................................................................................................................
(b) The ions in an ionic lattice are held together by an overall force of attraction.
(i) Describe the forces of attraction in an ionic lattice.
(1)
      ..............................................................................................................................................
      ..............................................................................................................................................
(ii) Suggest two forces of repulsion which exist in an ionic lattice.
(2)
      ..............................................................................................................................................
      ..............................................................................................................................................
(c) Part of the Born-Haber cycle for magnesium oxide, MgO, is shown below.

(i) Complete the empty box with the appropriate formulae and state symbols.
(2)
(ii) Identify the enthalpy changes represented by the letters A and C.
(2)
      ..............................................................................................................................................
      ..............................................................................................................................................
(iii) Give the expression for the enthalpy change F in terms of the other enthalpy changes to A and E.
(1)

F = 

(d) The lattice composed of the ions Mg2+ and O2− is stronger than a lattice composed of the ions Mg+ and O− .
(i) Explain, in terms of the charges on the ions and the size of the cations, why this is so.
(2)
      ..............................................................................................................................................
      ..............................................................................................................................................
(ii) Suggest how the lattice energy of Mg2+O2− would differ from that of Mg+O−.
(1)
      ..............................................................................................................................................
      ..............................................................................................................................................
(Total for question = 15 marks)

Q23.
The ionic radii in nm of some ions are given below.

(a) Which of the following compounds has the most exothermic lattice energy? They all
       have the same crystal structure.
(1)
   A      LiF
   B      LiCl
   C      CaO
   D      CaS
(b) Which of the following compounds will show the greatest difference between the
       experimental (Born-Haber) lattice energy and that calculated from a purely ionic
       model?
(1)
   A      LiF
   B      Li2O
   C      CaO
   D      CaS
(Total for question = 2 marks)

Q24.
Which of the graphs shows (from left to right) the trend in the ionic radius of the isoelectronic ions N3−, O2−, F−, Na+, Mg2+, Al3+?

(Total for question = 1 mark)

Unit 1 - Jun 2012
Q25.
Which of the following represents the process occurring when the enthalpy change of atomization of bromine is measured?
   A   ½Br2(l) → Br(g)
   B   ½Br2(g) → Br(g)
   C   Br2(l) → Br+(g) + Br−(g)
   D   Br2(g) → Br+(g) + Br−(g)
(Total for question = 1 mark)
Q26.
Magnesium chloride, MgCl2, has two lattice energy values quoted in the data booklet. The first is the experimental value, obtained from the Born-Haber cycle, −2526 kJ mol−1; the second is the theoretical value, −2326 kJ mol−1. Why are the two values different?
   A    The cation polarizes the anion leading to some covalent bonding.
   B    The anion polarizes the cation leading to some covalent bonding.
   C    Magnesium chloride is a covalent substance.
   D    The results from the Born-Haber cycle are too inaccurate to be reliable.
(Total for question = 1 mark)

Q27.
An organic compound is represented by the skeletal formula shown below.

The compound is
   A   CH3CH2CH2CH(OH)CH2CH3
   B   (CH3)2CHC(OH)(CH3)2
   C   (CH3)2CHCH2CH(OH)CH3
   D   (CH3)2CHCH(OH)CH2CH3
(Total for question = 1 mark)
Unit 1 - Jan 2013
Q28.
Which of the following statements is evidence for the existence of ions in ionic compounds?
   A     Ionic compounds, in the solid state, conduct electricity.
   B     When any ionic compound in solution is electrolysed, the migration of ions can be seen.
   C     In electron density maps for ionic compounds, there is no single line representing electron density that surrounds both cations and anions.
   D     In electron density maps for ionic compounds, there are some single lines representing electron density that surround both cations and anions.
(Total for question = 1 mark)
Q29.
This question is about lithium iodide, an ionic salt.
(a)  Draw dot and cross diagrams for the lithium and iodide ions.  Show all the electrons in the lithium ion but only outer shell electrons in the iodide ion.
(2)

(b)  On the Born-Haber cycle below, fill in the missing formulae (including state symbols) and the missing enthalpy change.
(3)

(c)  Calculate the electron affinity of iodine, Eaff1[I(g)], using the data below.

(2)

(d)  The experimental lattice energy for lithium iodide is −759 kJ mol−1.  The theoretical lattice energy is different from this value.
        Will the experimental lattice energy be more negative or less negative than the theoretical lattice energy?  Justify your answer.
(3)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 ............................................................................................................................................. 
............................................................................................................................................. 
(e)  State and explain how electron affinity values change as you go down Group 7 from chlorine to iodine.
(2)
 ............................................................................................................................................. 
............................................................................................................................................. 
(Total for question = 12 marks)

Q30.
This question is about the preparation of the alum, potassium aluminium sulfate, KAl(SO4)212H2O.  It is a double salt consisting of potassium ions, aluminium ions and sulfate ions, and water of crystallization.
(a)  The first step of the preparation involves adding an excess of aluminium foil to 10 cm3 of 2 mol dm−3 potassium hydroxide to form potassium aluminate.
The equation for this reaction is

(i)   Write a balanced ionic equation for this reaction.
(1)

(ii)   Calculate the number of moles of potassium hydroxide used.
(1)

(iii)   Hence state the number of moles of aluminium that react with the potassium hydroxide.
(1)

(iv)   Use your answer to (iii) to calculate the mass of aluminium that reacts with the potassium hydroxide. Use the Periodic Table as a source of data.
(1)

(v)   Calculate the total mass of aluminium added to the potassium hydroxide if a 10% excess of aluminium is required.
(1)

(vi)   Identify two hazards in this first step of the preparation.
(2)
Hazard 1
 ............................................................................................................................................. 
 ............................................................................................................................................. 
Hazard 2
 ............................................................................................................................................. 
 ............................................................................................................................................. 
(b)  The second step of the reaction is the addition of a slight excess of 1 mol dm−3 sulfuric acid.
(i)   Balance the following equation for the reaction
(1)

(ii)   Calculate the volume of the 1 mol dm−3 sulfuric acid that reacts with the potassium aluminate.
(1)

(iii)   State how you would show that the acid had been added in excess.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
*(iv)   State and explain the steps necessary to obtain pure, dry crystals from the mixture.
(4)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 ............................................................................................................................................. 
............................................................................................................................................. 
 ............................................................................................................................................. 
(v)   Suggest the colour of the crystals.
(1)
 ............................................................................................................................................. 
(vi)   Suggest the formula of another metal ion which could form an alum, in combination with potassium and sulfate ions.
(1)
(Total for question = 17 marks)

Unit 1 - Jun 2013
Q31.
Which of the equations below represents the first electron affinity for oxygen?
   A    O2(g) + 2e− → 2O−(g)
   B    O2(g) − 2e− → 2O−(g)
   C    ½O2(g) + e− → O−(g)
   D    O(g) + e− → O−(g)

(Total for Question = 1 mark)

Q32.
Which of the following has the largest ionic radius?
   A    S2−
   B    Cl−
   C    K+
   D    Ca2+

(Total for Question = 1 mark)

Q33.
A drop of sodium manganate(VII) solution is placed at the centre of a piece of moist filter paper on a microscope slide. The ends of the paper are clipped to a 30 V DC power supply. After a few minutes,
   A    a purple colour has moved towards the positive terminal.
   B    a purple colour has moved towards the negative terminal.
   C    an orange colour has moved towards the positive terminal.
   D    an orange colour has moved towards the negative terminal.

(Total for Question = 1 mark)

Q34.
Which of the diagrams below best represents the shapes of the electron contours in sodium fluoride?

   A    

   B    

   C    

   D    

(Total for Question = 1 mark)

Q35.
Which of the following oxides would be expected to have the most exothermic lattice energy?

   A    Na2O
   B    MgO
   C    CaO
   D    K2O

(Total for Question = 1 mark)
Q36.
Which of the following quantities, used in the calculation of the lattice energy of lithium oxide, Li2O, has a negative value?
   A    The enthalpy change of atomization of lithium.
   B    The first ionization energy of lithium.
   C    The first electron affinity of oxygen.
   D    The second electron affinity of oxygen.

(Total for Question = 1 mark)

Q37.
(a)  In a mass spectrometer being used to determine relative atomic masses, gaseous atoms are ionized. The ions are then accelerated and deflected before being detected.

(i)  Explain how atoms are ionized in a mass spectrometer.
(1)
 ............................................................................................................................................. 
............................................................................................................................................. 

(ii)  How are the ions accelerated in a mass spectrometer?
(1)
 ............................................................................................................................................. 
 ............................................................................................................................................. 

(iii)  How are the ions deflected in a mass spectrometer?
(1)
 ............................................................................................................................................. 
 ............................................................................................................................................. 

(b)  The following data were obtained from the mass spectrum of a sample of platinum.

Calculate the relative atomic mass of platinum in this sample. Give your answer to one decimal place.
(2)

(c)  In which block of the Periodic Table is platinum found?
(1)
 ............................................................................................................................................. 
(d)  Most solids exist as lattice structures.
(i)  Complete the table, using a tick () if the substance conducts electricity or a cross () if the substance does not conduct electricity.
(2)

*(ii)  Explain the electrical conductivities of sodium and of sodium oxide in the solid and liquid states.
(3)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 ............................................................................................................................................. 
............................................................................................................................................. 

(Total for Question = 11 marks)

Q38.
In which of the following compounds is the anion most polarized?
   A    LiF
   B    LiI
   C    LiI
   D    KI

(Total for Question = 1 mark)

Q39.
Copper(II) sulfate solution, CuSO4(aq), can be made by adding an excess of solid copper(II) oxide, CuO, to boiling dilute sulfuric acid. This is an exothermic reaction.
The balanced equation for this reaction is

CuO(s) + H2SO4(aq) → CuSO4(aq) + H2O(l)
(a)  (i)  Complete the ionic equation for this reaction, including state symbols.
(2)
CuO(s) +                                                            
(ii)  Calculate the mass of copper(II) oxide needed, if a 10% excess is required, when 0.020 mol of sulfuric acid is completely reacted.
[Relative atomic masses: Cu = 63.5 and O = 16.0]
(2)

(b)  (i)  Suggest, with a reason, how the copper(II) oxide should be added to the boiling sulfuric acid.
(2)
 ............................................................................................................................................. 
............................................................................................................................................. 

(ii)  When the reaction is complete, the excess copper(II) oxide is removed by filtration.
To prepare crystals of copper(II) sulfate-5-water, CuSO4.5H2O, the resulting solution is boiled to remove excess water.
How would you know when sufficient water had been removed?
(1)
............................................................................................................................................. 
 ............................................................................................................................................. 

(iii)  After cooling the solution, crystals form. State the colour of the crystals.
(1)
 ............................................................................................................................................. 

(iv)  The crystals all have the same shape. What does this indicate about the arrangement of the ions?
(1)
 ............................................................................................................................................. 
 ............................................................................................................................................. 

(c)  (i)  Calculate the molar mass of copper(II) sulfate-5-water, CuSO4.5H2O. Remember to include the appropriate units in your answer. You will need to use the Periodic Table as a source of data.
(2)

(ii)  Calculate the percentage yield if 2.7 g of copper(II) sulfate-5-water is obtained from 0.020 mol of sulfuric acid.
(2)

(iii)  What is the most likely reason for the yield being well below 100%?
(1)
 ............................................................................................................................................. 
 ............................................................................................................................................. 

(d)  When the crystals are heated, they turn white. On adding water, they return to their original colour. Suggest a use for this reaction.
(1)
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(Total for Question = 15 marks)

Q40.
In the Born-Haber cycle for potassium iodide, which of the following steps is exothermic?
   A    K(s) → K(g)
   B    K(g) → K+(g) + e−
   C    ½I2(s) → I(g)
   D    I(g) + e− → I−(g)
(Total for Question = 1 mark)

Unit 1 - Jun 2014
Q41.
 Lattice energies can be calculated from experimental data using Born-Haber cycles.
In the table below are the enthalpy changes needed to calculate the lattice energy of sodium oxide, Na2O.

(a)  Define the term lattice energy.
(2)
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(b)  (i)  Write the correct letters from the table of data to label the Born-Haber cycle below.
(3)

(ii)  Calculate the lattice energy of sodium oxide, enthalpy change G, in kJ mol−1.
(2)

Answer = ........................................................... kj mol−1

*(c)  Predict whether the lattice energy of magnesium oxide, MgO, is more or less exothermic than the lattice energy of magnesium sulfide, MgS.
Justify your answer in terms of the sizes and the charges of the ions involved.
(4)
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 (Total for question = 11 marks)
Q42.
 The bonding in lithium iodide has some covalent character because
   A    the lithium ion polarizes the iodide ion.
   B    the iodide ion polarizes the lithium ion.
   C    there is a very large difference in electronegativity between lithium and iodine.
   D    there is a very small difference in electronegativity between lithium and iodine.
(Total for question = 1 mark)

Q43.
Which of the following data is not needed to calculate the lattice energy of sodium chloride when using a Born-Haber cycle?
   A    Enthalpy change of formation of sodium chloride.
   B    Enthalpy change of atomization of sodium.
   C    First ionization energy of chlorine.
   D    Electron affinity of chlorine.
(Total for question = 1 mark)

Q44.
 Which of the following contains a dative covalent bond?
   A    N2
   B    NH3
   C    NH2−
   D    NH4+
(Total for question = 1 mark)

Q45.
Which of the following ions would be deflected most in a mass spectrometer?
   A    35Cl+
   B    37Cl+
   C    37Cl2+
   D    (35Cl — 37Cl)+
(Total for question = 1 mark)

Q46.
A spot of blue solution was placed in the centre of a piece of moist filter paper supported on a microscope slide and the following experiment was carried out.

After some time, a blue colour moved towards the negative terminal, but no change was visible in the region of the positive terminal. This is because
   A    the negative ions in the solution were colourless and the positive ions were blue.
   B    the positive ions in the solution were colourless and the negative ions were blue.
   C    the negative ions in the solution had not moved but the positive ions had moved.
   D    the positive ions in the solution had not moved but the negative ions had moved.
(Total for question = 1 mark)

Q47.
Which of the following ions has the largest ionic radius?
   A    F−
   B    Mg2+
   C    Na+
   D    O2−
(Total for question = 1 mark)
Q48.
The lattice energy of magnesium oxide is more negative than the lattice energy of magnesium fluoride because
   A    oxide ions are larger than fluoride ions.
   B    oxide ions are larger than magnesium ions.
   C    oxide ions are more highly charged than fluoride ions.
   D    there is only one oxide ion but two fluoride ions per magnesium ion.
(Total for question = 1 mark)

Q49.
Naturally occurring samples of potassium contain three isotopes, 39K, 40K and 41K.
(a)  The isotopes can be separated in a mass spectrometer.
(i)  In the diagram below, particles are ionized at A and detected at D.

Name the processes occurring in the mass spectrometer at B and C.
(2)
B  ...................................................................................................................................... 
C  ...................................................................................................................................... 

(ii)  A sample of potassium has the following composition.

Calculate the relative atomic mass of this sample of potassium, giving your answer to two decimal places.
(2)

(iii)  Complete the table below to show the numbers of sub-atomic particles in an atom of each of the isotopes 39K and 41K.
(1)

(iv)  Complete the electronic configuration for an atom of 39K.
(1)
1s2 ........................................................................................................................... 

(v)  Why is potassium placed after argon in the Periodic Table, even though it has a smaller relative atomic mass?
(1)
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*(vi)  Explain why a potassium ion is smaller than a potassium atom.
(2)
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(b)  The type of bonding in potassium is metallic.
Draw a labelled diagram to illustrate the metallic bonding in potassium.
(2)

(c)  The graph shows the variation of first ionization energy with atomic number for six successive elements in the Periodic Table, including potassium. The letters used to label the elements are not their symbols.

(i)  Define the term first ionization energy.
(3)
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(ii)  Identify, with a reason, which element is potassium.
(2)
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(Total for question = 16 marks)