Unit 2 – Group 2 Periodic Table
Unit 2 - Jan 2009
Q1.
Which of these metals will give a lilac flame colour?
   A     Sodium
   B     Calcium
   C     Potassium
   D     Magnesium
(Total for question = 1 mark)

Q2.
Which of these metal hydroxides is the most soluble in water?
   A     Barium hydroxide
   B     Calcium hydroxide
   C     Magnesium hydroxide
   D     Strontium hydroxide
(Total for question = 1 mark)

Q3.
10.0 cm3 of 0.250 mol dm−3 potassium hydroxide solution was placed in a conical flask and titrated with 0.200 mol dm−3 hydrochloric acid solution, using phenolphthalein as an indicator.
(a)  What colour would phenolphthalein turn at the end-point in this titration?
(1)
   A     Colourless
   B     Pink
   C     Yellow
   D     Orange

(b)  The best piece of apparatus to accurately measure out 10.0 cm3 is a
(1)
   A     pipette
   B     burette.
   C     syringe.
   D     measuring cylinder.

(c)  What volume of 0.200 mol dm−3 hydrochloric acid solution was added by the
       end-point?
(1)
   A     8.00 cm3
   B     10.00 cm3
   C     12.50 cm3
   D     25.00 cm3
(Total for question = 3 marks)

Unit 2 - Jun 2009
Q4.
Which of the following statements is true?
   A     Calcium hydroxide is more soluble in water than magnesium hydroxide.
   B     Chlorine is more electronegative than fluorine.
   C     Iodine is a stronger oxidizing agent than bromine.
   D     The first ionization energy of barium is greater than that of strontium.
(Total for question = 1 mark)

Q5.
Calcium oxide, known as quicklime, is produced by the thermal decomposition of calcium carbonate, found naturally in limestone.
(a)  (i)  Explain what is meant by the term thermal decomposition.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 (ii)  Write an equation for the thermal decomposition of calcium carbonate, including state symbols.
(1)

(iii)  Other Group 2 carbonates can also undergo thermal decomposition.  Describe and explain the trend in thermal stability of carbonates down Group 2.
(3)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 (b)  0.121 g of an impure sample of quicklime was dissolved in 50.0 cm3 of hydrochloric acid, concentration 0.100 mol dm−3.  The excess hydrochloric acid was titrated with sodium hydroxide solution, concentration 0.100 mol dm−3, and 18.0 cm3 was needed to just neutralize the acid.  The indicator used was methyl orange.

       The equations for the reactions involved are shown below.

(i)  What colour would the indicator be at the end-point?
(1)
 ............................................................................................................................................. 
(ii)  Calculate the number of moles of hydrochloric acid that reacted with the sodium hydroxide solution.
(1)

(iii)  Calculate the number of moles of hydrochloric acid originally added to the quicklime.  Use this answer and your answer to (b)(ii) to calculate the number of moles of quicklime that reacted with the hydrochloric acid.
(2)

(iv)  Calculate the percentage purity of the sample of quicklime.  Give your answer to three significant figures.
(2)

(c)  (i)  Describe how to carry out a flame test on the impure sample of quicklime to confirm that it contains calcium ions.
(3)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 (ii)  If the flame test gave a green colour, in addition to the expected brick red flame, which Group 2 metal is also likely to be present?
(1)
 ............................................................................................................................................. 
(Total for question = 16 marks)

Unit 2 - Jan 2010
Q6.
Chlorides of Group 1 elements produce coloured flames when
   A     electrons become excited to a higher energy level.
   B     excited electrons move from a higher to a lower energy level.
   C     an outer electron leaves the atom.
   D     electrons move between the negative and positive ions.
(Total for question = 1 mark)

Q7.
This question is about the following compounds.
A     Barium carbonate
B     Lithium nitrate
C     Potassium bromide
D     Potassium nitrate

(a) Which compound gives a green colour in a flame test?
(1)
   A
   B
   C
   D

(b) Which compound gives a lilac colour in a flame test and does not decompose on heating?
(1)
   A
   B
   C
   D
(Total for question = 2 marks)

Q8.
Which of the following could not be an element in Group 2?
   A     An element with an oxide which forms a solution of pH 10.
   B     An element with an insoluble sulfate.
   C     An element with a chloride which is liquid at room temperature.
   D     An element with a carbonate which decomposes on heating.
(Total for question = 1 mark)

Q9.
Magnesium nitrate, Mg(NO3)2, decomposes when it is heated. One product is the brown gas, nitrogen dioxide.
(a)  (i)  Write an equation for this reaction. State symbols are not required.
(2)

(ii)  Calcium nitrate decomposes in a similar way to magnesium nitrate, but at a higher temperature.
Explain why the two nitrates have different stability to heat.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
(b)  Sodium nitrate decomposes to give different products to magnesium nitrate. Write an equation for the decomposition of sodium nitrate. State symbols are not required.
(1)

(c)  A student suggested that the structure of the nitrate ion, NO3−, is

Scientists have found that the bonds between nitrogen and oxygen in the nitrate ion are all the same length. Is the student's suggestion supported by this evidence? Explain your answer.
(1)

 ............................................................................................................................................. 
(d)  Nitrogen dioxide gas can dimerize to dinitrogen tetroxide, N2O4, a very pale yellow gas, as shown in the equation below.

(i)  What would you see when an equilibrium mixture of these gases is warmed gently?  Explain your answer.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 (ii)  Explain why an equilibrium mixture of these gases eventually becomes paler in colour when the pressure on it is increased.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 (e)  Two Maxwell-Boltzmann distributions showing the energy of particles in a gas at different temperatures, T1 and T2, are shown below. The activation energy for the reaction is labelled EA.

Use the distributions to explain why gases react faster when the temperature is increased.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 (Total for question = 12 marks)

Q10.
Which of the following trends occurs going down the elements in Group 2?
   A     The solubility of the hydroxides increases.
   B     The first ionization energy increases.
   C     The solubility of the sulfates increases.
   D     The stability of the carbonates to heat decreases.
(Total for question = 1 mark)

Q11.
20 cm3 of sulfuric acid, concentration 0.25 mol dm−3, was neutralized in a titration with barium hydroxide, concentration 0.50 mol dm−3. The equation for the reaction is

(a)  The volume of barium hydroxide required was
(1)
   A     10 cm3
   B     20 cm3
   C     25 cm3
   D     40 cm3

(b)  During the titration, the barium hydroxide was added until it was present in excess.The electrical conductivity of the titration mixture
(1)
   A     increased steadily.
   B     decreased steadily.
   C     increased and then decreased.
   D     decreased and then increased.
(Total for question = 2 marks)

Unit 2 - Jun 2010
Q12.
A student carried out an experiment to determine the concentration of ethanoic acid in a solution of vinegar.

·	 The student used a measuring cylinder to measure out 25.0 cm3 of the vinegar solution.
·	 This solution was then transferred to a 250 cm3 volumetric flask and the liquid level was carefully made up to the mark with distilled water.
·	 A pipette was used to transfer 25.0 cm3 portions of the acidic solution to conical flasks.
·	 The solution was then titrated with sodium hydroxide solution, concentration 0.100 mol dm−3, using phenolphthalein as the indicator. 

(a)  In this titration, what is the colour change of the phenolphthalein indicator?
(2)
From......................................to.........................................
(b)  Explain why the mean titre should be based only on titrations 2, 3 and 4.
(1)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 (c)  Calculate the mean titre in cm3.
(1)

(d)  (i)  Using your answer to (c), calculate the number of moles of sodium hydroxide in the mean titre.
(1)

(ii)  Hence state the number of moles of ethanoic acid, CH3COOH, in 25.0 cm3 of the diluted solution used in the titration.
(1)

(iii)  Calculate the concentration of the diluted acid solution in mol dm−3.
(1)

(iv)  Hence calculate the concentration of the ethanoic acid in the original vinegar solution in mol dm−3.
(1)

(v)  Use your answer from (d)(iv) to state the concentration of the ethanoic acid in the original vinegar solution in units of g dm−3.
[The molar mass of the ethanoic acid is 60 g mol−1.]
(1)

(e)  Suggest, with a reason, how the student's method of preparing the diluted solution could be improved.
(2)
Improvement
 ............................................................................................................................................. 
 ............................................................................................................................................. 
Reason
 ............................................................................................................................................. 
 ............................................................................................................................................. 
(f)  The burette used in the titration had an uncertainty for each reading of ± 0.05 cm3.
(i)  Identify, by letter, which ONE of the following should be regarded as the true value of the titre in titration number 2?
X     Between 27.90 and 28.00 cm3
Y     Between 27.925 and 27.975 cm3
Z     Between 27.85 and 28.05 cm3
(1)
 ............................................................................................................................................. 
(ii)  Suggest ONE reason why a student may obtain volumes outside the uncertainty of the burette when performing a titration.
(1)
 ............................................................................................................................................. 
 (Total for question = 13 marks)

Q13.
Compound X is a white solid. On heating this compound, a colourless, acidic gas is the only gaseous product. A flame test is carried out on the solid residue and a reddish flame is observed.
Compound X is
   A     calcium nitrate.
   B     calcium carbonate.
   C     magnesium carbonate.
   D     strontium nitrate.
(Total for question = 1 mark)
Q14.
Which of the following does not apply to the elements Mg, Ca, Sr and Ba in Group 2 of the Periodic Table?
   A     Their oxides, MO, are all basic.
   B     Their metal hydroxides, M(OH)2, become more soluble down the group.
   C     Their oxides, MO, react with water to form the metal hydroxide, M(OH)2.
   D     Their carbonates, MCO3, all decompose on gentle heating.
(Total for question = 1 mark)

Q15.
Calculate the volume of dilute sulfuric acid, concentration 0.500 mol dm−3, required to neutralize 20.0 cm3 aqueous sodium hydroxide, concentration 0.100 mol dm−3.

   A     2.0 cm3
   B     4.0 cm3
   C     8.0 cm3
   D     20.0 cm3
(Total for question = 1 mark)

Unit 2 - Jan 2011
Q16.
The flame produced by a compound containing barium in a flame test is
   A      colourless.
   B      green.
   C      red.
   D      yellow.
(Total for question = 1 mark)

Q17.
Which concentrated acid would be best for mixing with a salt to carry out a flame test?
   A      Hydrochloric acid
   B      Nitric acid
   C      Phosphoric(V) acid
   D      Sulfuric acid
(Total for question = 1 mark)

Q18.
As you go down Group 2 of the Periodic Table, which of the following decreases?
   A      The reactivity of the elements.
   B      The solubility of the hydroxides of the elements.
   C      The solubility of the sulfates of the elements.
   D      The thermal stability of the carbonates of the elements.
(Total for question = 1 mark)

Q19.
The ingredients list on the label of a commercial indigestion remedy states that each tablet contains 680 mg of calcium carbonate.

       To check this, the following experiment was carried out.

       One tablet was crushed. 50.0 cm3 of 1.00 mol dm−3 hydrochloric acid, an excess, was then added and the mixture was transferred to a volumetric flask. The volume was made up to exactly 100 cm3 with distilled water. 10.0 cm3 of this solution was titrated with 0.300 mol dm−3 sodium hydroxide solution. The following results were obtained.

(a) (i) What should be used to crush the tablet?
(1)
 ............................................................................................................................................. 
     (ii) Name a suitable indicator for the titration. State the colour change you would expect to see.
(2)
Indicator
 ............................................................................................................................................. 
Colour change from .......................................... to ................................................

(b) (i) Select appropriate readings and calculate the mean titre.
(1)

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

(iii) Use your answer to (ii) to write down the number of moles of hydrochloric acid left in 10.0 cm3 of the solution used in the titration.
(1)

(iv) Calculate the number of moles of hydrochloric acid left in 100 cm3 of solution.
(1)

(v)  50.0 cm3 of 1.00 mol dm−3 hydrochloric acid contains 0.0500 mol of hydrochloric acid.

    Use this and your answer to (iv) to calculate the number of moles of hydrochloric acid that reacted with the indigestion tablet.
(1)

(vi) The equation for the reaction between hydrochloric acid and calcium carbonate is:

                                      CaCO3(s) + 2HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l) 

                    Use this, and your answer to (v), to calculate the number of moles of calcium carbonate in one tablet.
(1)

(vii) Calculate the mass of calcium carbonate in one tablet.

      [Assume that the molar mass of CaCO3 is 100 g mol−1]
(1)

(viii) Suggest a reason, other than experimental error, why your value differs from the value given on the label.
(1)
 ............................................................................................................................................. 
............................................................................................................................................. 
(Total for question = 11 marks)

Unit 2 - Jun 2011
Q20.
This question is about the element chlorine and its compounds.
(a) When chlorine is bubbled through water, a solution of chlorine water forms. What is the colour of chlorine water?
(1)
 ............................................................................................................................................. 
(b) Chlorine water is added to potassium iodide solution.
      (i)   State the colour of the solution produced.
(1)
 ............................................................................................................................................. 
      (ii)  Write the ionic equation for the reaction, including state symbols.
(2)

(c) The concentration of chlorine water was found by taking 10.0 cm3 of solution, adding an excess of potassium iodide solution, and titrating with 0.0100 mol dm−3 of sodium thiosulfate solution. The experiment was repeated.
      The following results were obtained.

      (i)   Name a suitable indicator for the titration. State the colour change you would expect to see at the end point.
(2)
Indicator ...........................................

Colour change from ........................................... to ...........................................

      (ii)  Calculate the mean titre and use this value to calculate the number of moles of sodium thiosulfate used in the titration.
(1)
Mean titre = .................................... cm3
Moles of sodium thiosulfate

      (iii)  Complete the ionic equation for the reaction between iodine and thiosulfate ions.
(2)

      (iv)  Calculate the number of moles of iodine which reacted with the sodium thiosulfate solution.
(1)

      (v)   Hence state the number of moles of chlorine present in 10.0 cm3 of the chlorine water.
(1)

      (vi)  Calculate the concentration of the chlorine water, in mol dm−3.
(1)

(d) Potassium burns in chlorine to form potassium chloride.
      (i)   Give the colour of the flame when potassium burns in chlorine.
(1)
 ............................................................................................................................................. 
      (ii)  Write the equation for the reaction between potassium and chlorine. State symbols are not required.
(1)

(e) Concentrated sulfuric acid is added to potassium chloride in a test tube. Steamy fumes are given off which react with ammonia to give dense white smoke.
      (i)   Name the gas given off in this reaction.
(1)
 ............................................................................................................................................. 
      (ii)  Steamy fumes are observed at the mouth of the test tube. Explain how these fumes are formed.
(1)
 ............................................................................................................................................. 
      (iii)  The steamy fumes react with ammonia to give a dense white smoke. Identify the white smoke by name or formula.
(1)
 ............................................................................................................................................. 
(f) 2-chlorobutane can be made from butan-2-ol.
     (i)   Name the chemical you would add to butan-2-ol in the laboratory to make 2-chlorobutane.
(1)
 ............................................................................................................................................. 
     (ii)  2-chlorobutane reacts with alcoholic potassium hydroxide at a high temperature to form a mixture of gaseous alkenes.
            Draw a fully labelled diagram of the apparatus you would use to prepare and collect this mixture.
(3)

(Total for Question = 21 marks)

Q21.
This question concerns the trends in properties on descending Group 2 of the Periodic Table.
(a) What are the trends in solubility of sulfates and hydroxides down Group 2?
(1)
   A    Sulfates increase, hydroxides decrease.
   B    Sulfates decrease, hydroxides increase.
   C    Sulfates increase, hydroxides increase.
   D    Sulfates decrease, hydroxides decrease.

(b) What are the trends in thermal stability of carbonates and nitrates down Group 2?
(1)
   A    Carbonates increase, nitrates decrease.
   B    Carbonates decrease, nitrates increase.
   C    Carbonates increase, nitrates increase.
   D    Carbonates decrease, nitrates decrease.

(c) What are the trends in first ionization energy and electronegativity of the elements down Group 2?
(1)
   A    Ionization energy increases, electronegativity decreases.
   B    Ionization energy decreases, electronegativity increases.
   C    Ionization energy increases, electronegativity increases.
   D    Ionization energy decreases, electronegativity decreases.
(Total for Question = 3 marks)
Unit 2 - Jan 2012
Q22.
The carbonates of Group 2 in the Periodic Table decompose on heating to form the corresponding metal oxide and carbon dioxide. A general equation for the reaction is

The thermal stability of these carbonates can be compared in the laboratory using the apparatus in the diagram below. The test tube on the left contains a sample of a metal carbonate and the tube on the right contains limewater.

(a) (i) State the measurement that you would make in this experiment.
(1)
 ............................................................................................................................................. 
 (ii) Suggest three ways to make sure that, when carrying out this experiment, the thermal stabilities of the different carbonates are compared fairly.
(3)
1
 ............................................................................................................................................. 
 ............................................................................................................................................. 
2
 ............................................................................................................................................. 
 ............................................................................................................................................. 
3
 ............................................................................................................................................. 
 ............................................................................................................................................. 
(b) (i) State the trend in the thermal stability of the metal carbonates as the group is descended.
(1)
 ............................................................................................................................................. 
*(ii) Explain this trend in stability.
(3)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 ............................................................................................................................................. 
(Total for question = 8 marks)
Q23.
When samples of magnesium nitrate, Mg(NO3)2, and calcium nitrate, Ca(NO3)2, are heated
   A  both compounds decompose to form the corresponding nitrite and oxygen.
   B  both compounds decompose to form the corresponding oxide, nitrogen dioxide and oxygen.
   C  magnesium nitrate decomposes to form magnesium nitrite and oxygen whereas calcium nitrate decomposes to form calcium oxide, nitrogen dioxide and oxygen.
   D  magnesium nitrate decomposes to form magnesium oxide, nitrogen dioxide and oxygen whereas calcium nitrate decomposes to form calcium nitrite and oxygen.
(Total for question = 1 mark)
Q24.
During a titration, when the solution in a pipette is transferred to a conical flask, a small amount of liquid remains in the tip of the pipette. This situation should be dealt with by
   A   leaving the liquid in the pipette which is calibrated to allow for it.
   B   slightly over-filling the pipette to compensate for the additional volume.
   C   carefully blowing the liquid out of the pipette to ensure that it is empty.
   D   repeating the titration.
(Total for question = 1 mark)
Q25.
A series of titrations is carried out using the same conical flask. Before carrying out each titration, the conical flask must be
   A   rinsed with ethanol.
   B   rinsed with distilled or deionised water.
   C   rinsed with the solution that it will contain.
   D   dried to remove all traces of liquid.
(Total for question = 1 mark)
Unit 2 - Jun 2012
Q26.
      The colour observed in a flame test is due to
   A      electrons jumping to a higher energy level, absorbing energy.
   B      electrons jumping to a higher energy level, emitting energy.
   C      electrons dropping from a higher energy level, absorbing energy.
   D      electrons dropping from a higher energy level, emitting energy.
(Total for question = 1 mark)
Q27.
      As Group 2 is descended
   A       the solubility of hydroxides and of sulfates increases.
   B       the solubility of hydroxides increases and of sulfates decreases.
   C       the solubility of hydroxides decreases and of sulfates increases.
   D       the solubility of hydroxides and of sulfates decreases.
(Total for question = 1 mark)
Q28.
      When solid samples of sodium carbonate and magnesium carbonate are strongly heated
   A       both compounds decompose.
   B       sodium carbonate decomposes but magnesium carbonate does not.
   C       magnesium carbonate decomposes but sodium carbonate does not.
   D       neither compound decomposes.
(Total for question = 1 mark)
Q29.
Metal nitrates decompose on heating. Potassium nitrate, KNO3, decomposes to form potassium nitrite and oxygen, whereas calcium nitrate, Ca(NO3)2, decomposes to form calcium oxide, nitrogen dioxide and oxygen.
(a) Write equations for the decomposition of each of these metal nitrates. State symbols are not required.
(2)
(i) Potassium nitrate

(ii) Calcium nitrate

(b) State two things that you would see when anhydrous calcium nitrate is heated.
(2)

*(c) Explain why potassium nitrate and calcium nitrate decompose to form different products.
(3)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 ............................................................................................................................................. 
 (Total for question = 7 marks)

Unit 2 - Jun 2013
Q30.
This is a question about Group 2 compounds.

Limewater is a solution of calcium hydroxide, commonly used in the identification of carbon dioxide gas. Since calcium hydroxide is only sparingly soluble in water, technicians often make the solution by adding an excess of the solid calcium hydroxide to the required volume of deionised water, shaking the container and then leaving the mixture to settle. In this way, a saturated solution is produced but it can be of variable concentration.

Two students were each given a sample of limewater, from the same batch, in order to determine its concentration. Using 50.0 cm3 portions of the limewater, they carried out titrations using 0.100 mol dm−3 hydrochloric acid. One of the students obtained the following results:

The student decided that the mean titre was 14.10 cm3
The equation for the reaction is:
Ca(OH)2(aq) + 2HCl(aq) → CaCl2(aq) + 2H2O(l)

(a)  (i)  Calculate the number of moles of hydrochloric acid that reacted.
(1)

(ii)  Calculate the number of moles of calcium hydroxide, Ca(OH)2, that reacted with the acid.
(1)

(iii)   the concentration of Ca(OH)2, in mol dm−3, in this sample of limewater.
(1)

(iv)  Calculate the concentration of Ca(OH)2, in g dm−3, in this sample of limewater. Use the Periodic Table as a source of data.
(2)

(v)  This student did not include the trial value when calculating the mean titre. Explain why.
(1)
 ............................................................................................................................................. 
 ............................................................................................................................................. 

(vi)  The second student obtained a different mean titre value for the experiment and thought that this difference may be due to the use of a faulty pipette.
Suggest a simple method, involving distilled water and a balance, by which the accuracy of the pipette in measuring out exactly 50.0 cm3 could be checked.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 

(b)  Complete the missing details from the reaction flowchart shown below, giving the condition for A and using chemical formulae for answers B, C and D. State symbols are not required.
(4)

(c)  In certain areas of the UK, calcium and magnesium carbonates tend to be deposited as an off-white solid on the inside surface of pipes and the surface of heating elements in kettles. These deposits can be removed by treatment with a weak acid. An equation for this is shown below.
CaCO3(s) + 2HA(aq) → CaA2(aq) + H2O(l) + CO2(g)
State one observation, other than the solid disappearing, that would be made when the above reaction is carried out.
(1)
 ............................................................................................................................................. 

(d)  The thermal stability of these carbonates depends on a combination of factors, including the size of their lattice energies.
Explain why the lattice energy of calcium carbonate is less exothermic than that of magnesium carbonate.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
(e)  Calcium and magnesium ions can be distinguished by the use of a flame test. State the difference in the flame colour and explain how colours in a flame are produced in terms of electronic transitions.
(3)
Calcium
 ............................................................................................................................................. 
Magnesium
 ............................................................................................................................................. 
Colour produced by
 ............................................................................................................................................. 
(Total for Question = 18 marks)
Q31.
Hydrochloric acid and sodium carbonate solution react as shown below.
2HCl(aq) + Na2CO3(aq) → 2NaCl(aq) + CO2(g) + H2O(l)
Which sample of sodium carbonate solution will be neutralized by 20 cm3 of 0.05 mol dm−3 hydrochloric acid?

(Total for Question = 1 mark)
Q32.
Going down Group 2 from calcium to barium
   A    the first ionization energy of the element increases.
   B    the strength of the metallic bonding increases.
   C    the polarizing power of the 2+ ion decreases.
   D    the stability of the nitrate to heat decreases. 
(Total for Question = 1 mark)
Q33.
(a)  (i)  An alkaline solution is produced when barium reacts with cold water. Write the equation for this reaction, including all state symbols.
(2)

(ii)  The reaction in (a)(i) is a redox reaction. State the initial and final oxidation number of any element that changes its oxidation number.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
(b)  Dilute hydrochloric acid is added to the solution produced in (a)(i). Write the equation for the reaction which occurs. State symbols are not required.
(1)

(c)  Dilute sulfuric acid is added to another sample of the solution produced in (a)(i). How would the appearance of the resulting mixture differ from the mixture produced in (b)? Explain this difference.
(2)
Appearance
 ............................................................................................................................................. 
Explanation
 ............................................................................................................................................. 
(d)  (i)  Two white powders are known to be barium carbonate and magnesium carbonate.
How could you distinguish between the two powders by heating them? [No practical details are required.]
Include the equation for the action of heat on one of these carbonates. State symbols are not required.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
Equation:
(ii)  Suggest another test, other than heating or the use of an acid, which could be used to distinguish between magnesium carbonate and barium carbonate. State the results for both compounds.
(2)
Test
 ............................................................................................................................................. 
Result with magnesium carbonate
 ............................................................................................................................................. 
Result with barium carbonate
 ............................................................................................................................................. 
 (Total for Question = 11 marks)

Q34.
A white solid produces oxygen when it is heated, but no other gases. The solid could be
   A    lithium nitrate.
   B    potassium nitrate.
   C    strontium nitrate.
   D    calcium oxide.
(Total for Question = 1 mark)

Unit 2 - Jun 2014
Q35.
Which of the following is the correct equation for the decomposition of the corresponding nitrate?
   A    4LiNO3 → 2Li2O + 4NO2 + O2
   B    4NaNO3 → 2Na2O + 4NO2 + O2
   C    Mg(NO3)2 → Mg(NO2)2 + O2
   D    Ba(NO3)2 → Ba(NO2)2 + O2
(Total for question = 1 mark)

Q36.
When a flame test is carried out on calcium iodide, the colour of the flame is
   A    yellow-red.
   B    pale green.
   C    purple.
   D    crimson.
(Total for question = 1 mark)

Q37.
This is a question about Group 2 elements and their compounds.
*(a) Explain why the first ionization energy of calcium (590 kJ mol−1) is greater than that of strontium (550 kJ mol−1). 
(2)
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 ............................................................................................................................................. 

(b)  (i)  Describe how you would carry out a flame test on a sample of a Group 2 metal salt.
(2)
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(ii)  What result of the flame test would confirm the presence of a barium salt?
(1)
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*(iii)  Explain, in terms of electronic transitions, how the result of the flame test arises.
(3)
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(c)  Barium reacts with water to form a clear, colourless solution.

(i)  Give the name or formula of the barium compound formed.
(1)
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(ii)  State another observation that would be made when barium reacts with water.
(1)
 ............................................................................................................................................. 

(d)  Barium reacts with chlorine gas to form barium chloride as shown in the equation below.
Ba(s) + Cl2(g) → BaCl2(s)
(i)  Use the changes in oxidation numbers to show that this is a redox reaction.
(2)
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(ii)  Write the ionic equation for the reaction between barium chloride solution and dilute sulfuric acid. Include state symbols in the equation.
(2)

(iii)  The reaction in (d)(ii) is used to test for sulfate ions.
Why is dilute hydrochloric acid added with the barium chloride solution in this test?
(1)
 ............................................................................................................................................. 

(e)  Magnesium carbonate, MgCO3, readily reacts with hydrochloric acid.
(i)  Write the equation for this reaction. State symbols are not required.
(1)

*(ii)  The rate of the reaction between powdered magnesium carbonate and dilute hydrochloric acid was monitored using the experimental apparatus shown below.

State two factors that would decrease the rate of this reaction, other than by changing the reaction temperature.
Explain how these two factors decrease the reaction rate.
(4)
Factor 1
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Explanation 1
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 ............................................................................................................................................. 
Factor 2
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Explanation 2
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(f)  Suggest why pressure has little or no effect on the rate of the reaction of magnesium oxide and hydrochloric acid, the equation for which is given below.
MgO(s) + 2HCl(aq) → MgCl2(aq) + H2O(l)
(1)
 ............................................................................................................................................. 
(Total for question = 21 marks)

Q38.
For barium, the third ionization energy is higher than the second ionization energy because
   A    there is an increase in the number of protons.
   B    there is an increase in the shielding.
   C    the ionic radius is greater.
   D    the electron being removed is closer to the nucleus.
(Total for question = 1 mark)

Q39.
Consider the following Group 2 compounds.

The solubility
   A    increases down the group for both hydroxides and sulfates.
   B    increases down the group for hydroxides but increases up the group for sulfates.
   C    increases up the group for hydroxides but increases down the group for sulfates.
   D    increases up the group for both hydroxides and sulfates.
(Total for question = 1 mark)