A LevelChemistryOCRExam Questions3. Periodic Table & EnergyGroup 2

Group 2 (OCR A Level Chemistry A): Exam Questions

Exam code: H432

3 hours39 questions

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Group 2

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1a
3 marks

The oxides of Group 2 elements produce basic solutions when dissolved in water.

i) State how many electrons a Group 2 element has in its outermost shell.

[1]

ii) State how a Group 2 element forms an ionic bond with non-metals.

   [1]

iii) State whether Group 2 elements act as oxidising or reducing agents.

[1]

How did you do?

1b
5 marks

Group 2 elements show a trend in ionisation energy.

i) Write an equation to show the first ionisation of a Group 2 metal, M.

[1]

ii) Describe the trend in first ionisation energy as you move down Group 2.

[1]

iii) Explain the trend in first ionisation energy as you move down Group 2.

[3]

How did you do?

1c
1 mark

Describe the trend in alkalinity as you move down Group 2.

How did you do?

1d
1 mark

State the approximate pH of the magnesium hydroxide solution, Mg(OH)2 (aq).

How did you do?

2a
4 marks

Group 2 metals dissolve in water to form metal hydroxides.

i) Write a balanced symbol equation for an aqueous Group 2 metal hydroxide, M(OH)2, dissociating into its component ions in solution.

[1]

ii) The solubilities of the Group 2 hydroxides, from magnesium to barium, are shown in Table 1. 

Table 1

Group 2 hydroxide

Solubility at 298 K (mol / 100 g of water)

Mg(OH)2 

2.0 x 10-5 

Ca(OH)2 

1.5 x 10-3

Sr(OH)2 

3.4 x 10-3

Ba(OH)2 

1.5 x 10-2

Describe the trend in solubility of the Group 2 hydroxides as you move down the group.

[1]

iii) Use your answers to parts (i) and (ii) to explain the trend in pH of the Group 2 metal hydroxides as you move down the group.

[2]

How did you do?

2b
3 marks

Group 2 metals react with sulfuric acid to produce a salt and hydrogen.

i) Write the balanced symbol equation, including state symbols, for the reaction of a Group 2 metal, M, with sulfuric acid to form a salt and hydrogen.

[2]

ii) Give the oxidation number of the Group 2 metal M in the salt formed.

[1]

How did you do?

2c
2 marks

The insoluble hydroxide and sulfate precipitates formed by magnesium and barium have medicinal uses. The barium precipitate is used in medical imaging of the digestive tract.

i) Name the white magnesium precipitate that has medicinal use.

[1]

ii) State what the white magnesium precipitate is used for.

[1]

How did you do?

2d
1 mark

Describe the trend in the reactions of the Group 2 metals with water.

How did you do?

3a
2 marks

Group 2 metals react with oxygen.

i) Write a balanced symbol equation, including state symbols, for the reaction of barium with oxygen.

[1]

ii) State whether barium is being oxidised or reduced in this reaction.

[1]

How did you do?

3b
3 marks

Write the balanced symbol equation, including state symbols, for the reaction of barium oxide, BaO, with hydrochloric acid to form a salt and one other product.

How did you do?

3c
2 marks

Write the balanced symbol equation, including state symbols, for the reaction of barium with sulfuric acid to form a salt and one other product.

How did you do?

3d
1 mark

Describe how calcium hydroxide is used within the agricultural industry.

How did you do?

4a
3 marks

Radium reacts with water in a redox reaction.

Ra (s) + 2H2O (l) → Ra(OH)2 (aq) + H2 (g)

i) Explain, in terms of electrons, what is meant by oxidation.

[1]

ii) Which element has been oxidised in this reaction?
Deduce the change in its oxidation number.

element ................ 

oxidation number changes from ............... to ...............

[2]

How did you do?

4b
2 marks

Write an equation, with state symbols, to represent the second ionisation energy of radium.

How did you do?

4c
2 marks

Use the equation in part a) to predict two observations that you would see during this reaction.

How did you do?

4d
1 mark

Predict a pH value for this solution.

How did you do?

5a
1 mark

Lime mortar has been used in building construction for thousands of years.

The first stage in making lime mortar is adding water to calcium oxide, CaO, to produce a thick paste called lime putty.

Write an equation for the reaction of calcium oxide with water.

State symbols are not required.

How did you do?

5b
2 marks

Lime putty is corrosive, and workers must wear gloves and eye protection when handling it.

i) Suggest the approximate pH of the solution formed when calcium oxide is added to an excess of water.

[1]

ii) Explain, in terms of the ions present, why this solution is corrosive.

[1]

How did you do?

5c
2 marks

Strontium oxide, SrO, reacts with water in the same way as calcium oxide.

i) Suggest the approximate pH of the solution formed when strontium oxide is added to an excess of water.

[1]

ii) State the trend in the alkalinity of the solutions formed when Group 2 oxides react with water.

[1]

How did you do?

5d
4 marks

Calcium hydroxide is spread on fields to treat soil that has become acidic.

i) Write an equation, including state symbols, for the reaction of calcium hydroxide with nitric acid, HNO3.

[2]

ii) Name the salt formed in this reaction.

[1]

iii) State the type of reaction taking place.

[1]

How did you do?

1a
2 marks

Different groups of the Periodic Table demonstrate different trends as you descend that group. Magnesium to barium demonstrate the trends in properties shown down Group 2 of the Periodic Table.

Give the formula of the Group 2 hydroxide, from magnesium to barium, which is the least soluble in water.

Give the formula of the Group 2 hydroxide, from magnesium to barium, which forms the solution with the highest pH.

How did you do?

1b
2 marks

The solubility of barium sulfate means that it is extremely useful in medicine.  

Give a medical use of barium sulfate and state why it is safe to use, despite solutions containing Ba2+ ions being toxic.

How did you do?

1c
3 marks

The elements of Group 2 will react with water.  

State the trend shown in the reactivity of the elements of Group 2 (Mg - Ba) when they react with water and give the equations for the reactions of magnesium with cold water and with steam. Include state symbols in your equations. 

How did you do?

1d
2 marks

The student had added the exact amount of calcium required to react with the hydrochloric acid used. After carrying out the experiment, the student accidentally added some more calcium. The student was surprised that the extra calcium still reacted.

Explain this observation. Include an equation in your answer.  

How did you do?

2a
1 mark

Give the full electron configuration for a magnesium ion, Mg2+.

How did you do?

2b
4 marks

Identify the element in Group 2, from magnesium to barium, which has the lowest first ionisation energy. 

Explain your answer. 

How did you do?

2c
4 marks

A group of students completed two experiments. In experiment 1, they added magnesium metal to nitric acid and in experiment 2, they added calcium metal to sulfuric acid. The students then compared the two reactions and found that a white solid had been produced in experiment 2.

The concentration of each acid was kept the same and the mass of each Group 2 metal used was also kept the same. 

Predict and explain which reaction would finish first, and name the white solid formed.

How did you do?

2d
2 marks

Write equations for the reactions taking place in Experiment 1 and Experiment 2.

How did you do?

3a
2 marks

Magnesium is frequently used in fireworks. It burns rapidly in oxygen, and it adds sparks which generally improves the appearance and brilliance of the firework.   

Write an equation to represent the reaction which takes place when a strip of magnesium is burned in oxygen and state an observation which would be made.

How did you do?

3b
5 marks

Group 2 compounds, such as the hydroxides of magnesium and calcium, have a number of other uses.

i) Write equations to show the formation of magnesium hydroxide and calcium hydroxide from their metals.

ii) Give an approximate pH value and use of each of the hydroxides. 

How did you do?

3c
3 marks

Group 2 elements will react with water.

A student added 20 cm3 of water to two boiling tubes. To one of the boiling tubes they added a small piece of calcium and to the other they added a small piece of barium.

State two observations that the student would make and how the observations would differ between the two boiling tubes.

How did you do?

3d
3 marks

The element strontium forms a nitrate, Sr(NO3)2, which decomposes on heating as shown below.

2Sr(NO3)2 (s) → 2SrO (s) + 4NO2 (g) + O2 (g)

Using oxidation numbers, explain why the reaction involves both oxidation and reduction.

How did you do?

4a
2 marks

The solubility of the hydroxides of Group 2 elements varies down the group.

State the trend in the solubility of the Group 2 hydroxides as you descend the group, and state the effect this has on the pH of the resulting solutions.

How did you do?

4b
3 marks

Compare the reactivity of barium with the reactivity of magnesium. Explain your answer.

How did you do?

4c
1 mark

A student watches a demonstration in which strontium is added to water.

The equation for the reaction is shown below.

Sr (s) + 2H2O (l) → Sr(OH)2 (aq) + H2 (g)

In terms of electron transfer, explain why strontium has been oxidised.

How did you do?

4d
1 mark

Suggest two compounds which could be reacted together to produce Sr(OH)2.

How did you do?

5a
1 mark

This question is about Group 1 and Group 2 metals of the Periodic Table.  

Give the electron configuration of the s block metal which has the highest first ionisation energy. 

How did you do?

5b
3 marks

Explain why the first ionisation energy of the element in part (a) is higher than the first ionisation energy of calcium.

How did you do?

5c
3 marks

A student reacts a Group 2 metal, M, with water.

M (s) + 2H2O (l)→ M(OH)2 (aq) + H2 (g)

The student measures the volume of hydrogen gas produced. 0.162 g of the metal produces 97.0 cm3 of gas measured at room temperature and pressure.

Identify the Group 2 metal, M. Show your working.

How did you do?

5d
2 marks

The student plans to repeat the experiment using the same mass of group 2 metal from further down the group.

Predict whether the volume of hydrogen produced would be greater than, less than or the same as the volume of the first experiment.

Explain your answer.

How did you do?

1a
3 marks

This question is about magnesium. 

Magnesium forms a nitrate, Mg(NO3)2 which decomposes on heating as shown below:

2Mg(NO3)2 (s) →   2MgO (s) + 4NO2 (g) + O2 (g)

Using oxidation numbers, explain why the reaction involves both oxidation and reduction. 

How did you do?

1b
4 marks

A student heats 4.46 g of the Mg(NO3)2 and collects the gas at room temperature and pressure, RTP. 

Calculate the volume of gas, in dm3, obtained by the student at RTP.

How did you do?

1c
8 marks

The values for the first, second and third ionisation energies of magnesium are shown in the table below.

 First ionisation energy 

 738 kJ mol-1

 Second ionisation energy

 1451 kJ mol-1

 Third ionisation energy 

7732 kJ mol-1

i) Write an equation for the second ionisation energy of magnesium.   

[2]

ii) Explain the trend in the first three ionisation energies of magnesium.

[3]

iii)   Explain why magnesium has a greater second ionisation energy than barium.

[3]

 

   

                                                               

How did you do?

1d
1 mark

Magnesium hydroxide or 'milk of magnesia' is used in indigestion tablets to neutralise stomach acid. 

Write an ionic equation to demonstrate this reaction. 

Include state symbols.

How did you do?

2a
2 marks

This question is about Group 2 elements.

Barium is silvery white but blackens when exposed to air, forming a coating of barium oxide.

Write a balanced symbol equation, including state symbols, for the reaction of barium with oxygen.

How did you do?

2b
4 marks

Barium can also react with water.

A student reacted 0.20 g of barium with 250 cm3 of water. 

i) Calculate the volume of gas, in cm3,  produced in this reaction at room temperature and pressure. 

[3]

ii) Calculate the concentration, in mol dm-3 of the barium hydroxide solution produced.

[1]

How did you do?

2c
5 marks

Describe and explain the trend in the reactivity of Group 2 elements with water. 

How did you do?

2d
2 marks

Explain why the reaction of calcium with water is a redox reaction. 

Use oxidation numbers in your answer.

How did you do?

2e
3 marks

The trend in solubility and strength as a base can also be observed going down Group 2. 

Explain how these two trends are connected. 

How did you do?

3a
6 marks

This question is about the reactions of Group 2 metals with acids. 

Group 2 metals react with dilute acids to form metal salts. 

Compare the reaction between strontium and dilute hydrochloric acid with strontium and dilute sulfuric acid.

Include a balanced symbol equation for each reaction with state symbols.

How did you do?

3b
3 marks

Explain why the reaction between calcium and hydrochloric acid is a redox reaction. 

Use oxidation numbers and half equations in your answer. 

How did you do?

3c
3 marks

A student prepared a sample of calcium chloride. They added the exact amount of calcium so that all of the HCl had reacted. They used 50 cm3 of 2.0 mol dm-3 HCl. 

Calculate the mass of calcium that was used. 

How did you do?

4a
2 marks

This question is about Group 2 hydroxides.

Samples of magnesium, calcium, strontium and barium are reacted with water to form their hydroxides. The resulting solutions are then filtered to collect the precipitates.

Explain the trend in the expected mass for the precipitates.

How did you do?

4b
2 marks

The table below shows the solubility data for the Group 2 metal hydroxides.

Group 2 metal hydroxide

Solubility / g dm-3 at 20 °C

Magnesium hydroxide

0.140

Calcium hydroxide

1.730

Strontium hydroxide

17.70

Barium hydroxide

38.90

A student determined that a 50 cm3 solution of an unknown Group 2 metal hydroxide contained 802 mg of the metal hydroxide.

Identify the metal hydroxide in the unknown sample.

How did you do?

4c
3 marks

Milk of magnesia, Mg(OH)2 is used to neutralise stomach acid. 

i) Write a balanced symbol equation for the reaction. Include state symbols.

[1]

ii) Describe the properties of magnesium hydroxide that make it suitable for use in the human body.

[2]

How did you do?

4d
2 marks

Calcium hydroxide is added to fields as lime by farmers to increase the pH of acidic soils. 

Give two reasons why calcium hydroxide is used instead of magnesium hydroxide.

How did you do?

5a
2 marks

Indigestion is caused by an excess of hydrochloric acid in the stomach. Antacid tablets contain a base that neutralises some of this acid.

Two brands of antacid tablet are compared.

  • Tablet A contains calcium carbonate, CaCO3

  • Tablet B contains magnesium hydroxide, Mg(OH)2

Write an equation for the reaction of each active ingredient with hydrochloric acid.

State symbols are not required.

How did you do?

5b
4 marks

Each tablet contains 1.00 g of its active ingredient.

Determine which tablet neutralises the greater amount of hydrochloric acid, and how many times greater this amount is.

How did you do?

5c
2 marks

Both active ingredients react with hydrochloric acid in the same molar ratio.

Explain why 1.00 g of the two ingredients does not neutralise the same amount of acid.

How did you do?

5d
4 marks

A student investigates one whole tablet A, which has a mass of 1.50 g.

The tablet is crushed and added to hydrochloric acid. The student finds that the tablet reacts with exactly 20.0 cm3 of 1.00 mol dm-3 hydrochloric acid.

None of the other ingredients in the tablet react with hydrochloric acid.

Calculate the percentage by mass of calcium carbonate in tablet A.

How did you do?

5e
4 marks

i) Barium hydroxide, Ba(OH)2, is also a Group 2 hydroxide.

Explain why barium hydroxide would not be suitable as the active ingredient in an antacid tablet.

[2]

ii) A patient who takes tablet A may belch shortly after swallowing it. A patient who takes tablet B does not.

Suggest an explanation for this difference. Use the equations in part a) in your answer.

[2]

How did you do?